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Masarwa D, Mimouni M, Aloni E, Kaiserman I. Tomographic Predictors of Ectasia Development After Keratorefractive Surgery. Cornea 2024; 43:545-551. [PMID: 38275916 DOI: 10.1097/ico.0000000000003465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 11/26/2023] [Indexed: 01/27/2024]
Abstract
PURPOSE The aim of this study was to identify the risk factors for postkeratorefractive surgery ectasia in unsuspicious tomographies and to report a new index coined diameter of peak locations (DPLs). METHODS All patients who underwent keratorefractive surgery between 2011 and 2018 at Care-Vision Laser Centers, Israel, and later developed ectasia were included. For each ectasia case, 3 matched controls were selected. Demographic and preoperative, intraoperative, and postoperative data were collected. Multivariate analysis was performed to evaluate the interdependence of the variables. RESULTS The retrospective study included 19 ectasia and 58 control eyes. There were no significant differences between the groups in ablation depth ( P = 0.73), preoperative spherical equivalent ( P = 0.12), percent tissue altered ( P = 0.71), residual stromal bed ( P = 0.73), and Ectasia Risk Score System ( P = 0.60). The anterior and the posterior symmetry index were significantly higher ( P < 0.001), and DPL was significantly tighter in the ectasia group ( P = 0.01). Binary multiple logistic regression found the symmetry index of the posterior cornea and DPL to be better predictors than age, percent tissue altered, Ectasia Risk Score System, residual stromal bed, and ablation depth. CONCLUSIONS A higher posterior symmetry index and a tighter DPL are predictors of ectasia in patients with otherwise normal tomographies. A tight DPL implies a weak area in the cornea, which is thin and slightly bulging, increasing the risk of this area becoming ectatic.
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Affiliation(s)
- Dua Masarwa
- Department of Ophthalmology, Barzilai Medical Center, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheba, Israel
| | - Michael Mimouni
- Care-Vision Laser Center, Tel Aviv, Israel; and
- Department of Ophthalmology, Rambam Health Care Campus, Affiliated with the Bruce and Ruth Rappaport, Technion-Israel Institute of Technology, Haifa, Israel
| | - Eyal Aloni
- Department of Ophthalmology, Barzilai Medical Center, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheba, Israel
| | - Igor Kaiserman
- Department of Ophthalmology, Barzilai Medical Center, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheba, Israel
- Care-Vision Laser Center, Tel Aviv, Israel; and
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Masarwa D, Blockstein K, Sela T, Munzer G, Kaiserman I. Tel-Aviv Protocol for Postrefractive Surgery Corneal Ectasia: A Case Series. Cornea 2024; 43:578-584. [PMID: 37983313 DOI: 10.1097/ico.0000000000003428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Accepted: 10/15/2023] [Indexed: 11/22/2023]
Abstract
PURPOSE The aim of this study was to describe the safety and efficacy of the Tel-Aviv Protocol (epithelial photorefractive keratectomy and corneal cross-linking) as a treatment for postrefractive surgery corneal ectasia. METHODS This study includes 8 eyes from 7 patients, each diagnosed with postrefractive surgery ectasia years after refractive surgery and treated with the Tel-Aviv Protocol. The procedure included transepithelial PRK using the EX500 excimer laser, a 50-μm laser ablation of the epithelium and anterior stroma, delivered on the visual axis with cyclotorsion correction, treating up to 50% of refractive astigmatism. After the epithelial photorefractive keratectomy, all patients underwent corneal cross-linking. RESULTS The mean keratometry (K) and maximal K both decreased [from 43.37 ± 2.23 to 41.84 ± 2.01 ( P = 0.03) and from 44.95 ± 3.08 to 42.78 ± 2.19 ( P = 0.03), respectively]. Astigmatism was significantly reduced (from 3.53 ± 2.36 to 0.88 ± 0.89 diopter; P = 0.02). Uncorrected visual acuity improved significantly in all patients from a mean of 0.56 ± 0.32 to 0.15 ± 0.14 logMAR ( P = 0.01). Best-corrected visual acuity improved from 0.22 ± 0.24 to 0.06 ± 0.06 logMAR ( P = 0.07; 1-tail P = 0.04). All patients maintained visual acuity during the follow-up period, up to 25 months, mean = 329 days. The Tel-Aviv Protocol was found to be safe [mean safety index: 1.63 ± 1.03 (range: 1.00-4)] and effective [mean efficacy index: 1.29 ± 0.66 (range: 0.71-2.1)]. CONCLUSIONS The Tel-Aviv Protocol, developed initially for keratoconus treatment, is a safe and promising procedure to stop postrefractive surgery ectasia progression while significantly improving vision, thereby avoiding keratoplasty.
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Affiliation(s)
- Dua Masarwa
- Department of Ophthalmology, Barzilai Medical Center, Ashkelon, Israel
| | - Keren Blockstein
- Department of Ophthalmology, Barzilai Medical Center, Ashkelon, Israel
| | - Tzahi Sela
- Care-Vision Laser Center, Tel Aviv, Israel; and
| | - Gur Munzer
- Care-Vision Laser Center, Tel Aviv, Israel; and
| | - Igor Kaiserman
- Department of Ophthalmology, Barzilai Medical Center, Ashkelon, Israel
- Care-Vision Laser Center, Tel Aviv, Israel; and
- Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheba, Israel
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Chong YJ, Azzopardi M, Hussain G, Recchioni A, Gandhewar J, Loizou C, Giachos I, Barua A, Ting DSJ. Clinical Applications of Anterior Segment Optical Coherence Tomography: An Updated Review. Diagnostics (Basel) 2024; 14:122. [PMID: 38248000 PMCID: PMC10814678 DOI: 10.3390/diagnostics14020122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 12/28/2023] [Accepted: 01/03/2024] [Indexed: 01/23/2024] Open
Abstract
Since its introduction, optical coherence tomography (OCT) has revolutionized the field of ophthalmology and has now become an indispensable, noninvasive tool in daily practice. Most ophthalmologists are familiar with its use in the assessment and monitoring of retinal and optic nerve diseases. However, it also has important applications in the assessment of anterior segment structures, including the cornea, conjunctiva, sclera, anterior chamber, and iris, and has the potential to transform the clinical examination of these structures. In this review, we aim to provide a comprehensive overview of the potential clinical utility of anterior segment OCT (AS-OCT) for a wide range of anterior segment pathologies, such as conjunctival neoplasia, pterygium, scleritis, keratoconus, corneal dystrophies, and infectious/noninfectious keratitis. In addition, the clinical applications of AS-OCT (including epithelial mapping) in preoperative planning and postoperative monitoring for corneal and refractive surgeries are discussed.
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Affiliation(s)
- Yu Jeat Chong
- Birmingham and Midland Eye Centre, Birmingham B18 7QH, UK; (A.R.); (I.G.); (A.B.)
- Modality Ophthalmology, Modality Partnership, Birmingham B19 1BP, UK;
| | - Matthew Azzopardi
- Department of Ophthalmology, Royal Free Hospital, London NW3 2QG, UK;
| | - Gulmeena Hussain
- University Hospitals Birmingham NHS Foundation Trust, Birmingham B15 2GW, UK;
| | - Alberto Recchioni
- Birmingham and Midland Eye Centre, Birmingham B18 7QH, UK; (A.R.); (I.G.); (A.B.)
- Academic Unit of Ophthalmology, Institute of Inflammation and Ageing, University of Birmingham, Birmingham B15 2TT, UK
| | - Jaishree Gandhewar
- New Cross Hospital, Royal Wolverhampton NHS Trust, Wolverhampton WV10 0QP, UK;
| | | | - Ioannis Giachos
- Birmingham and Midland Eye Centre, Birmingham B18 7QH, UK; (A.R.); (I.G.); (A.B.)
| | - Ankur Barua
- Birmingham and Midland Eye Centre, Birmingham B18 7QH, UK; (A.R.); (I.G.); (A.B.)
| | - Darren S. J. Ting
- Birmingham and Midland Eye Centre, Birmingham B18 7QH, UK; (A.R.); (I.G.); (A.B.)
- Academic Unit of Ophthalmology, Institute of Inflammation and Ageing, University of Birmingham, Birmingham B15 2TT, UK
- Academic Ophthalmology, School of Medicine, University of Nottingham, Nottingham NG7 2RD, UK
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Wagner FM, Sekundo W. Iatrogenic Keratectasia after Refractive Surgery - Causes, Prophylaxis, Therapy. Klin Monbl Augenheilkd 2023; 240:783-794. [PMID: 37348513 DOI: 10.1055/a-2073-8478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/24/2023]
Abstract
Iatrogenic keratectasia is induced thinning and protrusion of the cornea after laser refractive surgery. Known risk factors include an excessively thin postoperative residual stromal bed, a thicker flap, or preoperatively undetected evidence of preexisting subclinical keratoconus. The rate of post-refractive ectasia in eyes without identifiable preoperative risk factors is 20 per 100 000 eyes for photorefractive keratectomy, 90 per 100 000 eyes for laser in situ keratomileusis, and 11 per 100 000 eyes for small incision lenticule extraction. Traditional screening tools for preoperative risk include the ectasia risk score system and percentage of tissue alteration. More recent methods include corneal elastography and epithelial mapping, in addition to Artificial Intelligence methods for data analysis. Therapy includes contact lenses, cross-linking, implantation of intracorneal ring segments, penetrating or lamellar keratoplasty, and, in early studies, implantation of corneal lenticules.
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Affiliation(s)
- Felix Mathias Wagner
- Universitätsaugenklinik Mainz, Mainz, Deutschland
- Universitätsaugenklinik Marburg, Marburg, Deutschland
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Yücekul B, Dick HB, Taneri S. Systematic detection of keratoconus in OCT: corneal and epithelial thickness maps. J Cataract Refract Surg 2022; 48:1360-1365. [PMID: 35714335 DOI: 10.1097/j.jcrs.0000000000000990] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 06/08/2022] [Indexed: 11/25/2022]
Abstract
PURPOSE To detect keratoconus (KC) only by analyzing the corneal and epithelial map parameters and patterns in optical coherence tomography (OCT). SETTING Tertiary care refractive surgery center. DESIGN Retrospective data collection. METHODS Corneal and epithelial thickness maps of normal, manifest, and subclinical keratoconic eyes (according to the Belin-Ambrosio display, Pentacam) were evaluated using spectral-domain OCT (Zeiss Cirrus 5000 HD). A new 2-step decision tree was developed based on previous studies with another OCT device. In the first step, if at least 1 of the 4 independent parameters (pachymetry minimum, pachymetry minimum-median, pachymetry superonasal-inferotemporal, and epithelial superonasal-inferotemporal) overruns the cutoff values, the eye was suspicious for KC. In the second step, if the epithelial map showed concentric thinning and the thinnest point of the cornea and epithelium is coincident, the eye was classified as keratoconic. RESULTS 172 manifest keratoconic eyes (108 patients), 21 subclinical keratoconic eyes (20 patients), and 172 normal eyes (90 age-matched participants) were included in this study. Step 1 captured 100% of manifest and subclinical keratoconic eyes. Step 2 ruled out all suspicious but normal cases and, falsely, 2 subclinical keratoconic eyes. Our 2-step decision tree reached 100% specificity, 100% sensitivity in manifest KC, and 90.4% sensitivity in subclinical KC. CONCLUSIONS Pachymetric and epithelial map parameters and patterns in OCT can be used in the diagnosis of KC, including subclinical cases, yielding a high level of agreement with the commonly used diagnostic reference, the Belin-Ambrosio display. Further improvements by refining our algorithm and including an automated evaluation in the software are desirable.
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Affiliation(s)
- Burcu Yücekul
- From the Department of Ophthalmology, Haseki Training and Research Hospital, Istanbul, Turkey (Yücekul); Ruhr University, Bochum, Germany (Dick, Taneri); Zentrum für Refraktive Chirurgie, Augenzentrum am St. Franziskus Hospital, Muenster, Germany (Taneri)
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Co-axial acoustic-based optical coherence vibrometry probe for the quantification of resonance frequency modes in ocular tissue. Sci Rep 2022; 12:18834. [PMID: 36336702 PMCID: PMC9637745 DOI: 10.1038/s41598-022-21978-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 10/07/2022] [Indexed: 11/08/2022] Open
Abstract
We present a co-axial acoustic-based optical coherence vibrometry probe (CoA-OCV) for vibro-acoustic resonance quantification in biological tissues. Sample vibrations were stimulated via a loudspeaker, and pre-compensation was used to calibrate the acoustic spectrum. Sample vibrations were measured via phase-sensitive swept-source optical coherence tomography (OCT). Resonance frequencies of corneal phantoms were measured at varying intraocular pressures (IOP), and dependencies on Young´s Modulus (E), phantom thickness and IOP were observed. Cycling IOP revealed hysteresis. For E = 0.3 MPa, resonance frequencies increased with IOP at a rate of 3.9, 3.7 and 3.5 Hz/mmHg for varied thicknesses and 1.7, 2.5 and 2.8 Hz/mmHg for E = 0.16 MPa. Resonance frequencies increased with thickness at a rate of 0.25 Hz/µm for E = 0.3 MPa, and 0.40 Hz/µm for E = 0.16 MPa. E showed the most predominant impact in the shift of the resonance frequencies. Full width at half maximum (FWHM) of the resonance modes increased with increasing thickness and decreased with increasing E. Only thickness and E contributed to the variance of FWHM. In rabbit corneas, resonance frequencies of 360-460 Hz were observed. The results of the current study demonstrate the feasibility of CoA-OCV for use in future OCT-V studies.
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Gao HB, Pan ZG, Shen MX, Lu F, Li H, Zhang XQ. KeratoScreen: Early Keratoconus Classification With Zernike Polynomial Using Deep Learning. Cornea 2022; 41:1158-1165. [PMID: 35543584 DOI: 10.1097/ico.0000000000003038] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 02/16/2022] [Indexed: 12/13/2022]
Abstract
PURPOSE We aimed to investigate the usefulness of Zernike coefficients (ZCs) for distinguishing subclinical keratoconus (KC) from normal corneas and to evaluate the goodness of detection of the entire corneal topography and tomography characteristics with ZCs as a screening feature input set of artificial neural networks. METHODS This retrospective study was conducted at the Affiliated Eye Hospital of Wenzhou Medical University, China. A total of 208 patients (1040 corneal topography images) were evaluated. Data were collected between 2012 and 2018 using the Pentacam system and analyzed from February 2019 to December 2021. An artificial neural network (KeratoScreen) was trained using a data set of ZCs generated from corneal topography and tomography. Each image was previously assigned to 3 groups: normal (70 eyes; average age, 28.7 ± 2.6 years), subclinical KC (48 eyes; average age, 24.6 ± 5.7 years), and KC (90 eyes; average age, 25.9 ± 5.4 years). The data set was randomly split into 70% for training and 30% for testing. We evaluated the precision of screening symptoms and examined the discriminative capability of several combinations of the input set and nodes. RESULTS The best results were achieved using ZCs generated from corneal thickness as an input parameter, determining the 3 categories of clinical classification for each subject. The sensitivity and precision rates were 93.9% and 96.1% in subclinical KC cases and 97.6% and 95.1% in KC cases, respectively. CONCLUSIONS Deep learning algorithms based on ZCs could be used to screen for early KC and for other corneal ectasia during preoperative screening for corneal refractive surgery.
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Affiliation(s)
- He-Bei Gao
- Division of Health Sciences, Hangzhou Normal University, Hangzhou, China
- Department of Information, Wenzhou Polytechnic, Wenzhou, China
| | - Zhi-Geng Pan
- School of Artificial Intelligence, Nanjing University of Information Science & Technology, Nanjing, China
| | - Mei-Xiao Shen
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China ; and
| | - Fan Lu
- School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, China ; and
| | - Hong Li
- College of Computer Science and Artificial Intelligence, Wenzhou University, Wenzhou, China
| | - Xiao-Qin Zhang
- College of Computer Science and Artificial Intelligence, Wenzhou University, Wenzhou, China
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Lee J, Son BK, Kim TG, Jin KH. Ten-year Results after Conventional Corneal Cross-linking in Korean Patients with Progressive Keratoconus. JOURNAL OF THE KOREAN OPHTHALMOLOGICAL SOCIETY 2022. [DOI: 10.3341/jkos.2022.63.5.417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Purpose: To evaluate the long-term effects of conventional corneal cross-linking in patients with progressive keratoconus.Methods: A total of 18 eyes of 9 patients diagnosed with keratoconus were analyzed retrospectively. One eye was diagnosed with progressive keratoconus and conventional corneal crosslinking was performed. The other eye was classified as non-progressive and remained untreated. All patients were assessed with best corrected visual acuity (BCVA), maximum keratometry (Kmax), mean keratometry (Kmean), corneal astigmatism, and corneal thickness. Clinical data were collected before the procedure and at 1, 3, 6 months and 1 to 10 years after the procedure.Results: The BCVA significantly improved from 0.63 ± 0.18 logarithm of the minimum angle of resolution (logMAR) to 0.46 ± 0.25 logMAR at 10 years after conventional corneal crosslinking (p = 0.027). The Kmax and Kmean decreased from 65.90 ± 9.43 D and 52.82 ± 5.16 D to 62.83 ± 8.16 D and 51.52 ± 5.18 D, respectively (p = 0.021, p = 0.028, respectively). Corneal astigmatism decreased from 6.97 ± 2.21 D to 5.53 ± 1.64 D (p = 0.008). The thinnest corneal thickness decreased from 435.11 ± 53.37 μm to 369.22 ± 64.00 μm 1 month after the procedure (p = 0.008), and gradually improved over time. At 10 years, the thinnest corneal thickness increased to 410.11 ± 61.32 μm (p = 0.097). In the untreated eyes, the mean keratometry significantly increased after 4 years of follow-up, but other factors did not change significantly. Although corneal opacity persisted for up to 10 years in 3 eyes of the treatment group, there was no significant difference of BCVA compared to the treated eyes without corneal opacity (p = 0.714).Conclusions: In patients with progressive keratoconus, conventional corneal crosslinking is a safe and effective procedure that suppresses long-term progression.
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Azzam S, Abd-Elaziz K, Eissa S, Salah Y. Prevalence of keratoconus on screening of Egyptian LASIK candidates: A retrospective multicenter study. Middle East Afr J Ophthalmol 2022; 29:67-71. [PMID: 37123422 PMCID: PMC10138127 DOI: 10.4103/meajo.meajo_457_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 10/27/2021] [Accepted: 12/13/2022] [Indexed: 02/26/2023] Open
Abstract
PURPOSE This is a retrospective multicenter study to report the incidental discovery of keratoconus (clinical and subclinical) in a screening of laser vision correction (LVC) surgery candidates. METHODS This retrospective multicenter study was conducted on patients presenting for LVC in four Egyptian governorates (Cairo-Giza-6th of October-Beni Suef) during the year 2018. The patients were examined using the Pentacam HR (OCULUS Optikgeräte GmbH, Wetzlar, Germany) or Sirius (Costruzione Strumenti Oftalmici, Italy). The following parameters were evaluated: the axial curvature map, keratometry (Kmax and K2 on the posterior surface), minimum corneal thickness, anterior elevation, posterior elevation, Baiocchi-Calossi -Versaci index (Sirius), index of height decentration, and BAD-D (Pentacam). The prevalence of keratoconus cases was reported and data were analyzed. RESULTS A total of 46 out of 782 candidates presenting for LVC in 2018 were incidentally discovered as clinical or subclinical keratoconus cases and were excluded from performing the LVC procedure. CONCLUSION Screening of LVC candidates for keratoconus is a crucial tool to detect the incidence of the disease in the Egyptian population.
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Zhao L, Lin H, Hu Y, Chen X, Chen S, Zhang X. Corneal Lamb wave imaging for quantitative assessment of collagen cross-linking treatment based on comb-push ultrasound shear elastography. ULTRASONICS 2021; 116:106478. [PMID: 34174743 DOI: 10.1016/j.ultras.2021.106478] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 05/03/2021] [Accepted: 05/24/2021] [Indexed: 06/13/2023]
Abstract
Keratoconus, a serious corneal disorder, often causes highly irregular astigmatism and different degrees of visual impairment. Riboflavin/UVA corneal collagen cross-linking(CXL) is currently approved for effective treatment of keratoconus by enhancing the mechanical strength of collagen fibers in the cornea. However, few methods are capable of quantitatively and non-destructively assessing the mechanical properties of the cornea before and after CXL treatments. This study developed a corneal viscoelasticity imaging method based on comb-push ultrasound shear elastography (CUSE) and implemented this method on a Verasonics™ Vantage 256 ultrasound open system with a high-frequency linear array ultrasound transducer. Push beams were generated by three teeth each consisting of 10 elements (working frequency = 10.41 MHz) for inducing Lamb wave propagation in the cornea, and then the system immediately switched to the plane wave imaging mode using 60 elements in the middle (working frequency = 18 MHz). This method can provide a high-resolution 2D Lamb wave velocity image overlapping with a B-mode image as well as quantitative viscoelasticity estimation according to experimentally obtained phase velocity dispersion of Lamb waves. The validation experiments were performed on ex vivo porcine corneas, and the accuracy of elasticity estimation was verified by a tensile test. The results showed that the shear elasticity increased and the viscosity decreased after CXL treatment. The shear elasticity results (reported as mean ± standard deviation) of one control group with no CXL treatment and three CXL-treated groups named as 10 min, 30 min, and 60 min groups according to UV irradiation time were 14.62 ± 3.38 kPa, 49.47 ± 3.63 kPa, 116.54 ± 23.99 kPa, and 197.89 ± 39.64 kPa, respectively, which was in agreement with the results of tensile tests. The ultrasound safety measurement indicated that this method could have acceptable safety, but further to ocular tissue and vision function. The study demonstrated the possibility of using a commercial ultrasound system to obtain high-resolution images of corneal mechanical properties as well as the ability to quantify changes induced by CXL treatment. Therefore, the proposed method could serve as a helpful tool in the studies related in corneal biomechanics.
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Affiliation(s)
- Linfeng Zhao
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, China
| | - Haoming Lin
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, China
| | - Yaxin Hu
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, China
| | - Xin Chen
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, China
| | - Siping Chen
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, China
| | - Xinyu Zhang
- School of Biomedical Engineering, Health Science Center, Shenzhen University, Shenzhen, China; National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Shenzhen, China; Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, Shenzhen, China.
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Corneal Tomography Multivariate Index (CTMVI) effectively distinguishes healthy corneas from those susceptible to ectasia. Biomed Signal Process Control 2021. [DOI: 10.1016/j.bspc.2021.102995] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Update and Review of Diagnosis and Management of Post-Refractive Surgery Ectasia. J Cataract Refract Surg 2021; 48:487-499. [PMID: 34486581 DOI: 10.1097/j.jcrs.0000000000000808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 08/18/2021] [Indexed: 11/25/2022]
Abstract
ABSTRACT Post-Refractive Surgery Ectasia is a serious, sight-threatening, and highly - avoided complication seen after the following procedures: Laser in situ Keratomileusis, Photorefractive Keratectomy, Small Incision Lenticule Extraction, Radial and/or Arcuate Keratotomy. Specific risk factors may include age, corneal thickness, degree of refractive error, corneal topographic changes including irregular astigmatism, percent tissue ablation, and residual stromal bed. Biomarkers may be a new option to help indicate who is at greatest risk for ectasia. Visual aids including glasses or contacts lenses are often required to achieve optimal vision. Collagen crosslinking is the only treatment thought to stop progression of ectasia and prevent keratoplasty. Other surgical options may include topography-guided phototherapeutic keratectomy and intrastromal corneal ring segments. Ultimately an "ounce of prevention is a pound of cure" so careful preoperative screening and ultimately offering the safest and most effective treatments for patients is arguably the most important job of the refractive surgeon.
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Kim JY, Lee H, Joo CK, Hyon JY, Kim TI, Kim JH, Kim JK, Cho EY, Choi JE, Lee NR, Tchah HW. Three-Year Follow-Up of Laser In Situ Keratomileusis Treatments for Myopia: Multi-Center Cohort Study in Korean Population. J Pers Med 2021; 11:jpm11050419. [PMID: 34065718 PMCID: PMC8156820 DOI: 10.3390/jpm11050419] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/03/2021] [Accepted: 05/08/2021] [Indexed: 11/16/2022] Open
Abstract
This multi-center cohort study included 3401 myopic laser in situ keratomileusis (LASIK) procedures conducted in 1756 myopia patients between 2002 and 2005. Pre- and postoperative uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), and manifest refraction spherical equivalent (SE) were recorded. Factors predicting low postoperative efficacy (defined as a postoperative UCVA < 0.5) were identified using univariate and multivariate logistic regression analysis. Compared with 1 month postoperatively, logMAR UCVA at 3 months postoperatively was significantly decreased (p = 0.002) and that at 2 and 3 years was significantly increased (p < 0.001). LogMAR BCVA at 2 years postoperatively was significantly decreased compared with 1 month postoperatively (p = 0.008). Over the 3-year postoperative period, overall refractive predictability within ±1.00 D and ±0.50 D ranged from 69.0% to 86.2% and from 43.3% to 67.8%, respectively. This also decreased from 1 month to 6 months postoperatively (p < 0.005). Multivariate logistic regression analysis using generalized estimating equations, revealed that higher preoperative SE (odds ratio [OR], 2.58 and 7.23; p < 0.001) and lower preoperative BCVA (OR, 2.44; p = 0.003) were predictive of a low postoperative efficacy. In summary, myopic LASIK can be effective and safe with a high refractive predictability in a Korean population, but myopic regression occurs over time. Higher preoperative SE and lower preoperative BCVA are predictive of a low postoperative efficacy.
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Affiliation(s)
- Jae-Yong Kim
- Department of Ophthalmology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-Y.K.); (H.L.)
| | - Hun Lee
- Department of Ophthalmology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-Y.K.); (H.L.)
| | - Choun-Ki Joo
- Department of Ophthalmology and Visual Science, Kangnam St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea;
| | - Joon-Young Hyon
- Department of Ophthalmology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam 13620, Korea;
| | - Tae-Im Kim
- Department of Ophthalmology, Institute of Vision Research, Corneal Dystrophy Research Institute, Yonsei University College of Medicine, Seoul 03722, Korea;
| | - Jin-Hyoung Kim
- Department of Ophthalmology, Ilsan Paik Hospital, Inje University of Korea, Koyang 10380, Korea;
| | - Jin-Kuk Kim
- B&VIIT Eye Center, Seoul 06615, Korea; (J.-K.K.); (E.-Y.C.)
| | - Eun-Young Cho
- B&VIIT Eye Center, Seoul 06615, Korea; (J.-K.K.); (E.-Y.C.)
| | - Ji-Eun Choi
- National Evidence-Based Healthcare Collaborating Agency, Seoul 04554, Korea; (J.-E.C.); (N.-R.L.)
| | - Na-Rae Lee
- National Evidence-Based Healthcare Collaborating Agency, Seoul 04554, Korea; (J.-E.C.); (N.-R.L.)
| | - Hung-Won Tchah
- Department of Ophthalmology, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; (J.-Y.K.); (H.L.)
- Correspondence:
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Falavarjani KG, Modarres M, Joshaghani M, Azadi P, Afshar AE, Hodjat P. Interocular differences of the Pentacam measurements in normal subjects. Clin Exp Optom 2021; 93:26-30. [DOI: 10.1111/j.1444-0938.2009.00446.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
| | - Mehdi Modarres
- Eye Research Center, Iran University of Medical Sciences, Tehran, Iran E‐mail:
| | - Mahmoud Joshaghani
- Eye Research Center, Iran University of Medical Sciences, Tehran, Iran E‐mail:
| | - Pejvak Azadi
- Eye Research Center, Iran University of Medical Sciences, Tehran, Iran E‐mail:
| | | | - Parsa Hodjat
- Eye Research Center, Iran University of Medical Sciences, Tehran, Iran E‐mail:
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Baptista PM, Ambrosio R, Oliveira L, Meneres P, Beirao JM. Corneal Biomechanical Assessment with Ultra-High-Speed Scheimpflug Imaging During Non-Contact Tonometry: A Prospective Review. Clin Ophthalmol 2021; 15:1409-1423. [PMID: 33854295 PMCID: PMC8039844 DOI: 10.2147/opth.s301179] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 03/05/2021] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND In recent years, increasing interest has arisen in the application of data from corneal biomechanics in many areas of ophthalmology, particularly to assist in the detection of early corneal ectasia or ectasia susceptibility, to predict corneal response to surgical or therapeutic interventions and in glaucoma management. Technology has evolved and, recently, the Scheimpflug principle was associated with a non-contact air-puff tonometer, allowing a thorough analysis of corneal biomechanics and a biomechanically corrected intraocular pressure assessment, opening up new perspectives both in ophthalmology and in other medical areas. Data from corneal biomechanics assessment are being integrated in artificial intelligence models in order to increase its value in clinical practice. OBJECTIVE To review the state of the art in the field of corneal biomechanics assessment with special emphasis to the technology based on ultra-high-speed Scheimpflug imaging during non-contact tonometry. SUMMARY A meticulous literature review was performed until the present day. We used 136 published manuscripts as our references. Both information from healthy individuals and descriptions of possible associations with systemic diseases are described. Additionally, it exposed information regarding several fields of ocular pathology, from cornea and ocular surface through areas of refractive surgery and glaucoma until vascular and structural diseases of the chorioretinal unit.
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Affiliation(s)
- Pedro Manuel Baptista
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Porto, Portugal
| | - Renato Ambrosio
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, RJ, Brazil
- Department of Cornea and Refractive Surgery, Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil
- Department of Opthalmology, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
- Federal University of São Paulo (UNIFESP), São Paulo, Brazil
- Brazilian Study Group of Artificial Intelligence and Corneal Analysis - BrAIN, Rio de Janeiro & Maceió, Brazil
| | - Luis Oliveira
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Pedro Meneres
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Porto, Portugal
| | - Joao Melo Beirao
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
- Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Porto, Portugal
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Baptista PM, Marta AA, Marques JH, Abreu AC, Monteiro S, Menéres P, Pinto MDC. The Role of Corneal Biomechanics in the Assessment of Ectasia Susceptibility Before Laser Vision Correction. Clin Ophthalmol 2021; 15:745-758. [PMID: 33642854 PMCID: PMC7903962 DOI: 10.2147/opth.s296744] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 01/20/2021] [Indexed: 01/02/2023] Open
Abstract
Purpose To describe the tomographic and corneal biomechanical status of a sample of eyes excluded from LVC and to present the differences in biomechanical behavior in relation to cutoffs of clinical- and tomography-based screening methods used in clinical practice. Patients and Methods Observational cross-sectional study including 61 eyes from 32 consecutive patients who were excluded from LVC in our department. Clinical and demographic data were collected from the patients’ clinical records. Tomographic data was assessed with a Scheimpflug camera (Pentacam, OCULUS®). Ablation depth (µm) and residual stromal bed (µm) were calculated by the WaveLight® EX500 laser system software (Alcon, EUA). The corneal biomechanical assessment was made through ultra-high speed Scheimpflug imaging during noncontact tonometry (Corvis ST, OCULUS®). Several ectasia risk scores were analyzed. Results Mean age was 31.0±6 years old and mean manifest spherical equivalent was −2.01 ± 2.3D. Belin–Ambrósio deviation index was the tomographic parameter with higher proportion of eyes within the ectasia high risk interval. In the biomechanical assessment, more than 95% of eyes met the criteria for ectasia susceptibility in four of the first generation and in two of the second generation parameters. In a cutoff based comparative analysis, eyes with Kmax ≥45.5 D, eyes with VCOMA <0 and eyes with ARTmax ≤350 presented significantly softer corneal biomechanical behavior. Conclusion The majority of eyes excluded from LVC in the present study met the criteria for ectasia susceptibility in several biomechanical parameters, validating the clinical and tomographic based screening prior to LVC in our center. Differences found in the biomechanical assessment regarding cutoffs used in clinical practice highlight its differential role in characterizing risk profile of these patients. Tomography should not be overlooked and the integration of all data, including treatment-related parameters, can be the future of risk ectasia screening prior LVC.
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Affiliation(s)
- Pedro Manuel Baptista
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal.,Instituto de Ciências Biomédicas Abel Salazar, Porto, Portugal
| | - Ana Ambrósio Marta
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - João Heitor Marques
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Ana Carolina Abreu
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Sílvia Monteiro
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
| | - Pedro Menéres
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal.,Instituto de Ciências Biomédicas Abel Salazar, Porto, Portugal
| | - Maria do Céu Pinto
- Ophthalmology Department, Centro Hospitalar Universitário do Porto, Porto, Portugal
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17
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Xu M, Ramirez-Garcia MA, Narang H, Buckley MR, Lerner AL, Yoon G. Individualized Characterization of the Distribution of Collagen Fibril Dispersion Using Optical Aberrations of the Cornea for Biomechanical Models. Invest Ophthalmol Vis Sci 2021; 61:54. [PMID: 32866268 PMCID: PMC7463181 DOI: 10.1167/iovs.61.10.54] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The spatial distribution of collagen fibril dispersion has a significant impact on both corneal biomechanical and optical behaviors. The goal of this study was to demonstrate a novel method to characterize collagen fibril dispersion using intraocular pressure (IOP)-induced changes in corneal optical aberrations for individualized finite-element (FE) modeling. Methods The method was tested through both numerical simulations and ex vivo experiments. Inflation tests were simulated in FE models with three assumed patterns of collagen fibril dispersion and experimentally on three rhesus monkey corneas. Geometry, matrix stiffness, and the IOP-induced changes in wavefront aberrations were measured, and the collagen fibril dispersion was characterized. An individualized corneal model with customized collagen fibril dispersion was developed, and the estimated optical aberrations were compared with the measured data. Results For the theoretical investigations, three assumed distributions of fibril dispersion were all successfully characterized. The estimated optical aberrations closely matched the measured data, with average root-mean-square (RMS) differences of 0.29, 0.24, and 0.10 µm for the three patterns, respectively. The overall features of the IOP-induced changes in optical aberrations were estimated for two ex vivo monkey corneas, with average RMS differences of 0.57 and 0.43 µm. Characterization of the fibril dispersion in the third cornea might have been affected by corneal hydration, resulting in an increased RMS difference, 0.8 µm. Conclusions A more advanced corneal model with individualized distribution of collagen fibril dispersion can be developed and used to improve our ability to understand both biomechanical and optical behaviors of the cornea.
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Affiliation(s)
- Mengchen Xu
- Department of Mechanical Engineering, University of Rochester, Rochester, New York, United States
| | - Manuel A Ramirez-Garcia
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States
| | - Harshita Narang
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States
| | - Mark R Buckley
- Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States
| | - Amy L Lerner
- Department of Mechanical Engineering, University of Rochester, Rochester, New York, United States.,Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States
| | - Geunyoung Yoon
- Flaum Eye Institute, The Institute of Optics, Center for Visual Science, Department of Biomedical Engineering, University of Rochester, Rochester, New York, United States
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18
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Bykhovskaya Y, Rabinowitz YS. Update on the genetics of keratoconus. Exp Eye Res 2020; 202:108398. [PMID: 33316263 DOI: 10.1016/j.exer.2020.108398] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/04/2020] [Accepted: 12/07/2020] [Indexed: 02/07/2023]
Abstract
In the past few years we have seen a great acceleration of discoveries in the field of keratoconus including new treatments, diagnostic tools, genomic and molecular determinants of disease risk. Recent genome-wide association studies (GWAS) of keratoconus cases and population wide studies of variation in central corneal thickness and in corneal biomechanical properties confirmed already identified genes and found many new susceptibility variants and biological pathways. Recent findings in genetic determinants of familial keratoconus revealed functionally important variants and established first mouse model of keratoconus. Latest transcriptomic and expression studies started assessing novel non-coding RNA targets in addition to identifying tissue specific effects of coding genes. First genomic insights into better prediction of treatment outcomes are bringing the advent of genomic medicine into keratoconus clinical practice.
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Affiliation(s)
- Yelena Bykhovskaya
- Cornea Genetic Eye Institute, Department of Surgery and Board of the Governors Regenerative Medicine Institute, Beverly Hills, Cedars-Sinai, Los Angeles, CA, United States.
| | - Yaron S Rabinowitz
- Cornea Genetic Eye Institute, Department of Surgery and Board of the Governors Regenerative Medicine Institute, Beverly Hills, Cedars-Sinai, Los Angeles, CA, United States
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19
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Abstract
Ectatic corneal disease (ECD) comprises a group of disorders characterized by progressive thinning and subsequent bulging of the corneal structure. Different phenotypes have been recognized, including keratoglobus, pellucid marginal degeneration (PMD), and keratoconus (KC). Keratoconus has been widely investigated throughout the years, but the advent of laser refractive surgery boosted an immediate need for more knowledge and research about ectatic diseases. This article discusses nomenclature of ectatic disease, etiology and pathogenesis, along with treatment options, with special focus ok KC and forme fruste keratoconus.
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20
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Pavlatos E, Chen S, Yang Y, Wang Q, Huang D, Li Y. A Coincident Thinning Index for Keratoconus Identification Using OCT Pachymetry and Epithelial Thickness Maps. J Refract Surg 2020; 36:757-765. [PMID: 33170283 DOI: 10.3928/1081597x-20200925-01] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 09/10/2020] [Indexed: 02/02/2023]
Abstract
PURPOSE To develop a coincident thinning (CTN) index to differentiate between keratoconic and healthy corneas using optical coherence tomography (OCT) measurements of pachymetry and epithelial thickness. METHODS Pattern deviation maps of pachymetry and epithelial thickness were generated using Fourier-domain OCT images of the cornea. The co-localized thinning of the two maps was quantified using a novel CTN index, which was calculated from Gaussian fits of the regions of maximum relative thinning. The CTN index was validated using k-fold cross-validation, and its classification performance was compared to minimum pachymetry and maximum keratometry. RESULTS A total of 82 normal eyes and 133 eyes within three groups of keratoconus severity were evaluated. The pattern deviation maps for the keratoconic eyes showed relative thinning that was larger in magnitude and more strongly correlated with the Gaussian function compared to normal eyes (all P < .01). The distance between the pachymetric and epithelial maximum relative thinning locations was significantly smaller for the keratoconic eyes than for the normal eyes (all P < .02). The CTN index was significantly larger for all three keratoconus groups compared to normal eyes (all P < .0001). The CTN index demonstrated a sensitivity of 100% in detecting manifest keratoconus, 100% for subclinical keratoconus, and 56% for forme fruste keratoconus. The overall classification accuracy was better for the CTN index (93%) than for minimum pachymetry (86%) and maximum keratometry (86%). CONCLUSIONS The CTN index is a highly sensitive measure of coincident pachymetric and epithelial thinning. It provides valuable information for detecting and monitoring early to moderate keratoconus. [J Refract Surg. 2020;36(11):757-765.].
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21
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Soundarya B, Sachdev GS, Ramamurthy S, Dandapani R. Ectasia after keratorefractive surgery: Analysis of risk factors and treatment outcomes in the Indian population. Indian J Ophthalmol 2020; 68:1028-1031. [PMID: 32461422 PMCID: PMC7508091 DOI: 10.4103/ijo.ijo_1580_19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Purpose: To analyze the risk factors in eyes developing ectasia following keratorefractive procedures. In addition, the study assessed visual outcomes following various treatment modalities for ectasia. Methods: In this retrospective study, data of patients who underwent keratorefractive procedures, presenting to the refractive services of a tertiary eye care hospital in South India between January 2016 and May 2019 was analyzed. Of these, the eyes that developed ectasia were noted and the possible risk factors were determined. Visual outcomes following treatment with corneal collagen crosslinking (CXL) with or without intracorneal ring segment implantation (ICRS) or topography-guided corneal ablation (T-PRK) were analyzed. Results: Forty eyes of 26 patients developed ectasia following keratorefractive procedures, with a mean interval of 73.1± 45.4 months between primary procedure and ectasia development. Of these, 14 patients had bilateral presentation. Identifiable risk factors included ablation depth >75 μm (59.25%), percentage of tissue altered (PTA) >40% (48.14%), residual stromal bed <300 μm (22.22%), mean refractive spherical equivalent >8 D (25.92%), inferior–superior (I–S) asymmetry >1.4D (7.40%), central corneal thickness (CCT) <500 μm (7.40%), Belin Ambrosio Display (BAD) >2.5 (7.40%), posterior float elevation maximum ≥18 μm (3.70%), and pellucid marginal degeneration (PMD; 3.70%). Conclusion: Our study shows that only 70% of the eyes demonstrated an identifiable risk factor for the development of ectasia. Ablation depth of >75 μm and the PTA >40% were the most common risk factors. Treatment following CXL with ICRS or T-PRK demonstrated significantly better visual outcomes in comparison with CXL alone.
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Affiliation(s)
- B Soundarya
- Refractive Services, The Eye Foundation, Coimbatore, Tamil Nadu, India
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22
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Yang K, Xu L, Fan Q, Gu Y, Song P, Zhang B, Zhao D, Pang C, Ren S. Evaluation of new Corvis ST parameters in normal, Post-LASIK, Post-LASIK keratectasia and keratoconus eyes. Sci Rep 2020; 10:5676. [PMID: 32231236 PMCID: PMC7105482 DOI: 10.1038/s41598-020-62825-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 03/17/2020] [Indexed: 12/17/2022] Open
Abstract
The aim of this study was to evaluate the distribution of new Corneal Visualisation Scheimpflug Technology (Corvis ST) parameters in normal, Post-laser in situ keratomileusis (LASIK), Post-LASIK keratectasia (KE) and keratoconus (KC) eyes, and explore the diagnostic ability of these parameters in distinguishing KE from LASIK eyes. Twenty-three normal eyes, 23 LASIK eyes, 23 KE eyes and 23 KC eyes were recruited in this study. The following new Corvis ST parameters were measured: Max Inverse Radius, deformation amplitude (DA) Ratio Max [2 mm], Pachy Slope, DA Ratio Max [1 mm], Ambrosio’s relational thickness horizontal (ARTh), Integrated Radius, stiffness parameter at first applanation (SP-A1) and Corvis biomechanical index (CBI). The general linear model, linear regression model, relation analysis and receiver operating characteristic (ROC) curve were performed. The Max Inverse Radius, DA Ratio Max [2 mm], Pachy Slope, DA Ratio Max [1 mm], Integrated Radius and CBI in LASIK eyes, KE eyes and KC eyes were higher than in normal eyes, while the ARTh and SP-A1 parameters were lower than in normal eyes. The KE eyes had higher Max Inverse Radius, DA Ratio Max [2 mm], Pachy Slope, DA Ratio Max [1 mm], Integrated Radius, and lower SP-A1 value than LASIK eyes (all P < 0.05). The central corneal thickness was related to the Pachy Slope (r = −0.485), ARTh (r = −0.766), SP-A1 (r = 0.618) in KE eyes (all P < 0.05). The area under the ROC curve of Integrated Radius, Max Inverse Radius, DA Ratio Max [2 mm] and SP-A1 were above 0.800 in identifying KE from LASIK eyes. Thus, the new Corvis ST parameters were different between LASIK and KE eyes, suggesting that they might be helpful in distinguishing KE eyes from LASIK eyes. However, a further multi-center and large sample study is necessary to confirm these findings.
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Affiliation(s)
- Kaili Yang
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China
| | - Liyan Xu
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China
| | - Qi Fan
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China
| | - Yuwei Gu
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China
| | - Peng Song
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China
| | - Bo Zhang
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China
| | - Dongqing Zhao
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China
| | - Chenjiu Pang
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China.
| | - Shengwei Ren
- Henan Provincial People's Hospital, Henan Eye Hospital, Henan Eye Institute, People's Hospital of Zhengzhou University, Henan University People's Hospital, Zhengzhou, 450003, China.
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Utility of regional epithelial thickness measurements in corneal evaluations. Surv Ophthalmol 2020; 65:187-204. [DOI: 10.1016/j.survophthal.2019.09.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Revised: 09/10/2019] [Accepted: 09/16/2019] [Indexed: 11/19/2022]
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24
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Sheludchenko VM, Osipyan GA, Yusef NY, Khraystin K, Alharki L, Dzhalili RA. [Bandage lamellar-optical keratoplasty for post-excimer laser keratectasia]. Vestn Oftalmol 2019; 135:171-176. [PMID: 31691656 DOI: 10.17116/oftalma2019135052171] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
INTRODUCTION According to various sources, occurrence rate of keratectasia (KE) after Laser in situ Keratomileusis (LASIK) ranges from 0.04 to 0.2%. No known technique for keratorefractive surgery eliminates the probability. Neither corneal cross-linking, nor implantation of polymeric segments can completely prevent its development. PURPOSE To treat KE after LASIK with bandage lamellar-optical keratoplasty (BLOK) surgery and to evaluate the results. MATERIAL AND METHODS The study included 22 patients with KE after LASIK divided into two groups. The first group consisted of 6 patients; they underwent BLOK surgery using a segment transplant 1.5 mm in width and 180-220 µm in thickness. The second group included 16 patients who underwent BLOK surgery using 2.75 mm wide, 290-350 µm thick allogeneic transplant of individual length. The follow-up lasted 4 years. RESULTS In the first group, uncorrected visual acuity (UCVA) improved by 0.4±007, in the second group - by 0.46±0.15. After two years, two patients had their transplant exchanged for a wider one due to ectasia progression. Corneal refraction was stable at 45.36±1.47 Diopters in all other patients of the first group. In the second group, it was consistently between 40.6 and 45.7 Diopters. The main complication of the BLOK surgery was displacement of the edge of the corneal flap formed during LASIK - occurred in 4 patients. CONCLUSION Bandage lamellar-optical keratoplasty proved effective in treating patients with KE after LASIK, leading to improvement of visual acuity, strengthening of the cornea and normalization of its surface; it slows further progression of ectasia.
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Affiliation(s)
- V M Sheludchenko
- Research Institute of Eye Diseases, 11A Rossolimo St., Moscow, Russian Federation, 119021
| | - G A Osipyan
- Research Institute of Eye Diseases, 11A Rossolimo St., Moscow, Russian Federation, 119021; Center Vision Recovery, 108 Lobachevskogo St., Moscow, Russian Federation, 119361
| | - N Yu Yusef
- Research Institute of Eye Diseases, 11A Rossolimo St., Moscow, Russian Federation, 119021; Center Vision Recovery, 108 Lobachevskogo St., Moscow, Russian Federation, 119361
| | - Kh Khraystin
- Research Institute of Eye Diseases, 11A Rossolimo St., Moscow, Russian Federation, 119021
| | - L Alharki
- Research Institute of Eye Diseases, 11A Rossolimo St., Moscow, Russian Federation, 119021
| | - R A Dzhalili
- Research Institute of Eye Diseases, 11A Rossolimo St., Moscow, Russian Federation, 119021
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25
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To See or Not to See: A Systematic Review of the Importance of Human Ocular Surface Cytokine Biosignatures in Ocular Allergy. Cells 2019; 8:cells8060620. [PMID: 31226821 PMCID: PMC6627738 DOI: 10.3390/cells8060620] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 06/12/2019] [Accepted: 06/19/2019] [Indexed: 12/19/2022] Open
Abstract
Cytokines are key cell signalling proteins in a number of immune and homeostatic pathways of the human body. In particular, they mediate intracellular mechanisms of allergy on the ocular surface by triggering cellular responses that result in typical physiological ocular allergy symptoms, such as itchiness, watery eyes, irritation, and swelling. Given the recent research focus in optometry on the aetiology of corneal ectasia subtypes like keratoconus, there is an increasing need for the development of new clinical diagnostic methods. An increasing trend is evident among recent publications in cytokine studies, whereby the concentrations of cytokines in healthy and disease states are compared to derive a specific cytokine profile for that disease referred to as ‘biosignatures’. Biosignatures have diagnostic applications in ocular allergy as a cheap, non-invasive alternative to current techniques like IgE antibody testing and skin prick tests. Cytokine detection from tear samples collected via microcapillary flow can be analysed either by enzyme-linked immunosorbent assays (ELISA), multiplex magnetic bead assays, or immunoblot assays. Characterising patient hypersensitivities through diagnostic tests is the first step to managing exposure to triggers. Investigating cytokine biosignatures in ocular allergy and their links to physiology are imperative and will be the focus of this systematic review article.
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26
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Shao P, Eltony AM, Seiler TG, Tavakol B, Pineda R, Koller T, Seiler T, Yun SH. Spatially-resolved Brillouin spectroscopy reveals biomechanical abnormalities in mild to advanced keratoconus in vivo. Sci Rep 2019; 9:7467. [PMID: 31097778 PMCID: PMC6522517 DOI: 10.1038/s41598-019-43811-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 04/27/2019] [Indexed: 12/27/2022] Open
Abstract
Mounting evidence connects the biomechanical properties of tissues to the development of eye diseases such as keratoconus, a disease in which the cornea thins and bulges into a conical shape. However, measuring biomechanical changes in vivo with sufficient sensitivity for disease detection has proven challenging. Here, we demonstrate the diagnostic potential of Brillouin light-scattering microscopy, a modality that measures longitudinal mechanical modulus in tissues with high measurement sensitivity and spatial resolution. We have performed a study of 85 human subjects (93 eyes), consisting of 47 healthy volunteers and 38 keratoconus patients at differing stages of disease, ranging from stage I to stage IV. The Brillouin data in vivo reveal increasing biomechanical inhomogeneity in the cornea with keratoconus progression and biomechanical asymmetry between the left and right eyes at the onset of keratoconus. The receiver operating characteristic analysis of the stage-I patient data indicates that mean Brillouin shift of the cone performs better than corneal thickness and maximum curvature respectively. In conjunction with morphological patterns, Brillouin microscopy may add value for diagnosis of keratoconus and potentially for screening subjects at risk of complications prior to laser eye surgeries.
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Affiliation(s)
- Peng Shao
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Amira M Eltony
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Theo G Seiler
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, 02114, USA.,Institute for Refractive and Ophthalmic Surgery (IROC), Zürich, 8002, Switzerland.,Universitätsklinik für Augenheilkunde, Inselspital, Bern, 3010, Switzerland
| | - Behrouz Tavakol
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Roberto Pineda
- Massachusetts Eye and Ear Infirmary, Boston, MA, 02114, USA
| | - Tobias Koller
- Institute for Refractive and Ophthalmic Surgery (IROC), Zürich, 8002, Switzerland
| | - Theo Seiler
- Institute for Refractive and Ophthalmic Surgery (IROC), Zürich, 8002, Switzerland.
| | - Seok-Hyun Yun
- Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, Boston, MA, 02114, USA. .,Harvard-MIT Health Sciences and Technology, Cambridge, MA, 02139, USA.
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Wen D, Li Q, Song B, Tu R, Wang Q, O'Brart DPS, McAlinden C, Huang J. Comparison of Standard Versus Accelerated Corneal Collagen Cross-Linking for Keratoconus: A Meta-Analysis. Invest Ophthalmol Vis Sci 2019; 59:3920-3931. [PMID: 30073363 DOI: 10.1167/iovs.18-24656] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To systematically compare epithelial-off standard (SCXL) to accelerated corneal collagen cross-linking (ACXL) for the treatment of keratoconus. Methods PubMed, Embase, the Cochrane Library, and the US trial registry were searched for trials comparing SCXL and ACXL for keratoconus up to October 2017. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated. Primary outcomes were changes in uncorrected distance visual acuity, maximum keratometry (Kmax), and mean keratometry (mean K). Secondary outcomes were changes in corrected distance visual acuity, mean refractive spherical equivalent, central corneal thickness (CCT), and endothelial cell density (ECD). Results Eleven trials were included. For primary outcomes, SCXL showed a greater reduction in Kmax (SMD 0.32; 95% CI 0.16, 0.48) than ACXL. For secondary outcomes, the decrease in CCT (SMD 0.32; 95% CI 0.03, 0.61) and ECD (SMD 0.26; 95% CI 0.06, 0.46) was less with ACXL than with SCXL. For the other outcomes, there were no statistically significant differences. Conclusions SCXL has a greater effect in terms of reduction in Kmax than ACXL, while ACXL induces less reduction in CCT and ECD than SCXL. Further well-designed randomized controlled trials comparing ACXL and SCXL are indicated.
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Affiliation(s)
- Daizong Wen
- School of Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Qi Li
- School of Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Benhao Song
- School of Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Ruixue Tu
- School of Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Qinmei Wang
- School of Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,Key Laboratory of Vision Science, Ministry of Health People's Republic of China, Wenzhou, Zhejiang, China
| | - David P S O'Brart
- Department of Ophthalmology, Guy's and St. Thomas' National Health Service Foundation Trust, London, United Kingdom.,King's College, London, United Kingdom
| | - Colm McAlinden
- Department of Ophthalmology, Glangwili Hospital, Hywel Dda University Health Board, Carmarthen, United Kingdom
| | - Jinhai Huang
- School of Ophthalmology and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.,Key Laboratory of Vision Science, Ministry of Health People's Republic of China, Wenzhou, Zhejiang, China
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Yip H, Chan E. Optical coherence tomography imaging in keratoconus. Clin Exp Optom 2019; 102:218-223. [PMID: 30793800 DOI: 10.1111/cxo.12874] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Revised: 12/23/2018] [Accepted: 01/01/2019] [Indexed: 11/28/2022] Open
Abstract
Optical coherence tomography (OCT) is being increasingly used as a tool in the diagnosis and management of keratoconus. While elevation-based topography remains essential, there is an expanding role for cross-sectional OCT imaging in the diagnosis of the disease. Images and measurements of corneal thickness, and in particular, epithelial thickness, may be important in diagnosing early cases, and following procedures such as intrastromal corneal ring segments, corneal transplants and corneal collagen cross-linking.
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Affiliation(s)
- Harry Yip
- School of Medicine, Monash University, Melbourne, Victoria, Australia
| | - Elsie Chan
- Ophthalmology, Royal Victorian Eye and Ear Hospital, Centre for Eye Research Australia, The University of Melbourne, Melbourne, Victoria, Australia
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Garcia-Ferrer FJ, Akpek EK, Amescua G, Farid M, Lin A, Rhee MK, Varu DM, Musch DC, Mah FS, Dunn SP. Corneal Ectasia Preferred Practice Pattern®. Ophthalmology 2019; 126:P170-P215. [DOI: 10.1016/j.ophtha.2018.10.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 10/09/2018] [Indexed: 02/07/2023] Open
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Salomão M, Hoffling-Lima AL, Lopes B, Belin MW, Sena N, Dawson DG, Ambrósio R. Recent developments in keratoconus diagnosis. EXPERT REVIEW OF OPHTHALMOLOGY 2018. [DOI: 10.1080/17469899.2018.1555036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Marcella Salomão
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Instituto Benjamin Constant, Rio de Janeiro, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
| | | | - Bernardo Lopes
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Instituto Benjamin Constant, Rio de Janeiro, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
- Department of Biomaterial Mechanics, University of Liverpool, Liverpool, Tucson, UK
| | - Michael W. Belin
- Department of Ophthalmology and Visual Sciences, University of Arizona, USA
| | - Nelson Sena
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Department of Ophthalmology, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
| | - Daniel G. Dawson
- Department of Ophthalmology, University of Florida, Gainesville, FL, USA
| | - Renato Ambrósio
- Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Department of Ophthalmology, Federal University of São Paulo, São Paulo, Brazil
- Department of Ophthalmology, Federal University of the State of Rio de Janeiro (UNIRIO), Rio de Janeiro, Brazil
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Enhanced Tomographic Assessment to Detect Corneal Ectasia Based on Artificial Intelligence. Am J Ophthalmol 2018; 195:223-232. [PMID: 30098348 DOI: 10.1016/j.ajo.2018.08.005] [Citation(s) in RCA: 98] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 08/01/2018] [Accepted: 08/02/2018] [Indexed: 12/17/2022]
Abstract
PURPOSE To improve the detection of corneal ectasia susceptibility using tomographic data. DESIGN Multicenter case-control study. METHODS Data from patients from 5 different clinics from South America, the United States, and Europe were evaluated. Artificial intelligence (AI) models were generated using Pentacam HR (Oculus, Wetzlar, Germany) parameters to discriminate the preoperative data of 3 groups: stable laser-assisted in situ keratomileusis (LASIK) cases (2980 patients with minimum follow-up of 7 years), ectasia susceptibility (71 eyes of 45 patients that developed post-LASIK ectasia [PLE]), and clinical keratoconus (KC; 182 patients). Model accuracy was independently tested in a different set of stable LASIK cases (298 patients with minimum follow-up of 4 years) and in 188 unoperated patients with very asymmetric ectasia (VAE); these patients presented normal topography (VAE-NT) in 1 eye and clinically diagnosed ectasia in the other (VAE-E). Accuracy was evaluated with ROC curves. RESULTS The random forest (RF) provided highest accuracy among AI models in this sample with 100% sensitivity for clinical ectasia (KC+VAE-E; cutoff 0.52), being named Pentacam Random Forest Index (PRFI). Considering all cases, the PRFI had an area under the curve (AUC) of 0.992 (94.2% sensitivity, 98.8% specificity; cutoff 0.216), being statistically higher than the Belin/Ambrósio deviation (BAD-D; AUC = 0.960, 87.3% sensitivity, 97.5% specificity; P = .006, DeLong's test). The optimized cutoff of 0.125 provided sensitivity of 85.2% for VAE-NT and 80% for PLE, with 96.6% specificity. CONCLUSION The PRFI enhances ectasia diagnosis. Further integrations with corneal biomechanical parameters and with the corneal impact from laser vision correction are needed for assessing ectasia risk.
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Topographic Asymmetry Indices: Correlation between Inferior Minus Superior Value and Index of Height Decentration. J Ophthalmol 2018; 2018:7875148. [PMID: 30370150 PMCID: PMC6189656 DOI: 10.1155/2018/7875148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2018] [Revised: 07/16/2018] [Accepted: 08/02/2018] [Indexed: 11/29/2022] Open
Abstract
Purpose To investigate the correlation between decentration index (index of height decentration, IHD) automatically calculated by the Pentacam HR software and the manually calculated inferior minus superior (I‐S) value. Setting Al Watany Eye Hospital, Cairo, Egypt. Methods In a retrospective study, history taking, clinical examination, and rotating Scheimpflug camera scanning (by Oculyzer II equivalent to Pentacam HR) were done to 128 eyes: 82 normal, 24 forme fruste keratoconus FFKC (apparently normal cornea with evident keratoconus in the fellow eye), and 22 keratoconus (KC). All cases of corneal scars or previous corneal surgeries were excluded. The (I‐S) value was calculated manually from 10 points astride the horizontal meridian. The IHD is calculated automatically by the device software 1.17r119. Results The mean (±SD) of (I‐S) value in normal, FFKC, and KC eyes were 0.30 ± 0.93, 0.11 ± 2.03, and 4.62 ± 3.89, respectively, and those of IHD were 0.008 ± 0.004, 0.011 ± 0.005, 0.066 ± 0.067, respectively. The two indices were highly correlated (p < 0.0001) with a correlation coefficient (r2 = 0.874). Deduced regression formulae linking the two indices were calculated. Conclusions The two topographic decentration indices are highly correlated. Deduced formulae were proposed linking them.
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Hwang ES, Perez-Straziota CE, Kim SW, Santhiago MR, Randleman JB. Distinguishing Highly Asymmetric Keratoconus Eyes Using Combined Scheimpflug and Spectral-Domain OCT Analysis. Ophthalmology 2018; 125:1862-1871. [PMID: 30055838 DOI: 10.1016/j.ophtha.2018.06.020] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 06/05/2018] [Accepted: 06/14/2018] [Indexed: 12/17/2022] Open
Abstract
PURPOSE To determine optimal objective, machine-derived variables and variable combinations from Scheimpflug and spectral-domain (SD) OCT imaging to distinguish the clinically unaffected eye in patients with asymmetric keratoconus (AKC) from a normal control population. DESIGN Retrospective case-control study. PARTICIPANTS Thirty clinically unaffected eyes with no physical findings on slit-lamp examination, no definitive abnormalities on corneal imaging, and corrected distance acuity of 20/20 or better from 30 patients with highly AKC eyes and 60 eyes from 60 normal control patients who had undergone uneventful LASIK with at least 2 years of stable follow-up (controls). METHODS Scheimpflug and SD OCT imaging were obtained in all eyes, and receiver operating characteristic (ROC) curves were generated to determine area under the curve (AUC), sensitivity, and specificity for each machine-derived variable and variable combination. MAIN OUTCOME MEASURES Distinguishing AKC eyes from controls as determined by AUC, sensitivity, and specificity. RESULTS No individual machine-derived metric from Scheimpflug or SD OCT technology yielded an AUC higher than 0.75. Combining 5 Scheimpflug metrics (index height decentration [IHD], index vertical asymmetry [IVA], pachymetry apex, inferior-superior value, and Ambrosio's Relational Thickness Maximum [ARTmax]) yielded the best Scheimpflug results (AUC 0.86, sensitivity 83%, specificity 83%). Combining 11 SD OCT thickness metrics (minimum-median, temporal outer, superior nasal outer, minimum, epithelium minimum-maximum, epithelial standard deviation, superior inner, superior outer, superior temporal outer, superior nasal inner, central) yielded the best SD OCT results (AUC 0.96, sensitivity 89%, specificity 89%). Combining 13 total Scheimpflug/SD OCT metrics yielded the best results overall (AUC 1.0, sensitivity 100%, specificity 100%). The most impactful variables in combined models included epithelial thickness variability and total focal corneal thickness variability from SD OCT and anterior curvature and topometric indices from Scheimpflug technology. No posterior corneal metrics were impactful in modeling. CONCLUSIONS Individual machine-derived metrics from Scheimpflug and SD OCT imaging poorly distinguished normal eyes from minimally affected eyes from patients with highly AKC. Combined SD OCT metrics performed better than combined Scheimpflug metrics. Combining anterior curvature and asymmetry indices from Scheimpflug with regional total thickness and epithelial thickness variability metrics from SD OCT clearly distinguished the 2 populations. Posterior corneal indices were not useful in distinguishing populations.
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Affiliation(s)
- Eric S Hwang
- Keck School of Medicine of the University of Southern California, Los Angeles, California
| | | | - Sang Woo Kim
- Department of Ophthalmology, Ulsan University of College of Medicine, Ulsan, South Korea
| | - Marcony R Santhiago
- USC Roski Eye Institute, Los Angeles, California; Department of Ophthalmology at University of Sao Paulo, Sao Paulo, Brazil; Department of Ophthalmology at Federal University of Rio de Janeiro, Sao Paulo, Brazil
| | - J Bradley Randleman
- Keck School of Medicine of the University of Southern California, Los Angeles, California; USC Roski Eye Institute, Los Angeles, California.
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Evaluation kornealer Biomechanik bei Keratokonus mithilfe dynamischer Ultra-High-Speed-Scheimpflug-Messung. Ophthalmologe 2018; 115:644-648. [DOI: 10.1007/s00347-018-0753-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Shajari M, Jaffary I, Herrmann K, Grunwald C, Steinwender G, Mayer WJ, Kohnen T. Early Tomographic Changes in the Eyes of Patients With Keratoconus. J Refract Surg 2018; 34:254-259. [DOI: 10.3928/1081597x-20180124-01] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 01/02/2018] [Indexed: 11/20/2022]
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36
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Salomão MQ, Hofling-Lima AL, Faria-Correia F, Lopes BT, Rodrigues-Barros S, Roberts CJ, Ambrósio R. Dynamic corneal deformation response and integrated corneal tomography. Indian J Ophthalmol 2018; 66:373-382. [PMID: 29480246 PMCID: PMC5859590 DOI: 10.4103/ijo.ijo_831_17] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 10/25/2017] [Indexed: 12/27/2022] Open
Abstract
Measuring corneal biomechanical properties is still challenging. There are several clinical applications for biomechanical measurements, including the detection of mild or early forms of ectatic corneal diseases. This article reviews clinical applications for biomechanical measurements provided by the Corvis ST dynamic non contact tonometer.
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Affiliation(s)
- Marcella Q Salomão
- Department for Ophthalmology, The Federal University of Sao Paulo, Sao Paulo, Brazil
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Department of Ophthalmology, Instituto De Olhos Renato Ambrósio and VisareRIO, Rio de Janeiro, Brazil
| | | | - Fernando Faria-Correia
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Department of Cornea and Refractive, Hospital De Braga, Porto
- Department of Cornea and Refractive, Institute CUF Porto, Porto
- Department of Ophthalmology, School of Health Sciences, University of Minho, Braga, Portugal
| | - Bernardo Teixeira Lopes
- Department for Ophthalmology, The Federal University of Sao Paulo, Sao Paulo, Brazil
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Department of Ophthalmology, Instituto De Olhos Renato Ambrósio and VisareRIO, Rio de Janeiro, Brazil
| | - Sandra Rodrigues-Barros
- Department for Ophthalmology, The Federal University of Sao Paulo, Sao Paulo, Brazil
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Departamento De Oftalmologia, Hospital Garcia de Orta, Almada, Portugal
| | - Cynthia J Roberts
- Department of Ophthalmology and Visual Science and Biomedical Engineering, The Ohio State University, Columbus, Ohio, USA
| | - Renato Ambrósio
- Department for Ophthalmology, The Federal University of Sao Paulo, Sao Paulo, Brazil
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
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Refractive Errors & Refractive Surgery Preferred Practice Pattern®. Ophthalmology 2018; 125:P1-P104. [DOI: 10.1016/j.ophtha.2017.10.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 10/02/2017] [Indexed: 11/19/2022] Open
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38
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Tang M, Li Y, Chamberlain W, Louie DJ, Schallhorn JM, Huang D. Differentiating Keratoconus and Corneal Warpage by Analyzing Focal Change Patterns in Corneal Topography, Pachymetry, and Epithelial Thickness Maps. Invest Ophthalmol Vis Sci 2017; 57:OCT544-9. [PMID: 27482824 PMCID: PMC4978086 DOI: 10.1167/iovs.15-18938] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To differentiate between keratoconus and contact lens-related corneal warpage by combining focal change patterns in anterior corneal topography, pachymetry, and epithelial thickness maps. Methods Pachymetry and epithelial thickness maps of normal, keratoconus, and warpage, and forme fruste keratoconus (FFK) eyes were obtained from a Fourier-domain optical coherence tomography (OCT). Epithelial pattern standard deviation (PSD) was calculated and combined with two novel indices, the Warpage Index and the Anterior Ectasia Index, to differentiate between normal, keratoconus, and warpage eyes. The values of the three parameters were compared between groups. Results The study included 22 normal, 31 keratoconic, 11 warpage, and 8 FFK eyes. The epithelial PSD was normal (< 0.041) for 100% normal eyes and abnormal (> 0.041) for 100% of keratoconic eyes, 81.8% of warpage eyes, and 87.5% of FFK eyes. The Anterior Ectasia Index of normal eyes (1.66 ± 0.74) was significantly lower than that for the keratoconus eyes (17.5 ± 7.17), the warpage eyes (2.98 ± 1.69), and the FFK eyes (6.95 ± 5.86). The Warpage Index was positive in all warpage eyes and negative for all keratoconic and FFK eyes except three wearing rigid gas-permeable contact lens. Conclusions The epithelial PSD can distinguish normal from keratoconus or warpage, but does not distinguish between these two conditions. The Anterior Ectasia Index is abnormal in keratoconus but not warpage. The Warpage Index is positive for warpage and negative for keratoconus, except in cases where keratoconus and warpage coexist. Together, the three parameters are strong tripartite discriminators of normal, keratoconus, and warpage.
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Wen D, McAlinden C, Flitcroft I, Tu R, Wang Q, Alió J, Marshall J, Huang Y, Song B, Hu L, Zhao Y, Zhu S, Gao R, Bao F, Yu A, Yu Y, Lian H, Huang J. Postoperative Efficacy, Predictability, Safety, and Visual Quality of Laser Corneal Refractive Surgery: A Network Meta-analysis. Am J Ophthalmol 2017; 178:65-78. [PMID: 28336402 DOI: 10.1016/j.ajo.2017.03.013] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 03/09/2017] [Accepted: 03/10/2017] [Indexed: 11/25/2022]
Abstract
PURPOSE To compare the postoperative efficacy, predictability, safety, and visual quality of all major forms of laser corneal refractive surgeries for correcting myopia. DESIGN Systematic review and network meta-analysis. METHODS Search of MEDLINE, EMBASE, Cochrane Library, and the US trial registry was conducted up to November 2015. Randomized controlled trials (RCT) reporting in accordance with the eligibility criteria were included in this review. We performed a Bayesian random-effects network meta-analysis. RESULTS Forty-eight RCTs were identified. For efficacy (uncorrected visual acuity [UCVA]), there were no statistically significant differences between any pair of treatments analyzed. The SUCRA (surface under the cumulative ranking curve) ranking (from best to worst) was femtosecond-based laser in situ keratomileusis (FS-LASIK), LASIK, small-incision lenticule extraction, femtosecond lenticule extraction (FLEx), photorefractive keratectomy (PRK), laser epithelial keratomileusis (LASEK), epipolis (Epi)-LASIK, transepithelial PRK (T-PRK). For predictability (refractive spherical equivalent [SE]), a statistically significant difference was found when FS-LASIK was compared with LASIK (odds ratio [OR] 2.29, 95% credible interval [CrI] 1.20-4.14), PRK (OR 2.16, 95% CrI 1.15-4.03), LASEK (OR 2.09, 95% CrI 1.08-4.55), and Epi-LASIK (OR 2.74, 95% CrI 1.11-6.20). The SUCRA ranking (from best to worst) was FS-LASIK, T-PRK, LASEK, PRK, LASIK, Epi-LASIK. There were no statistically significant differences in the safety (best spectacle-corrected visual acuity) comparisons. For both postoperative higher-order aberrations (HOAs) and contrast sensitivity (CS), there were no statistically significant differences between any pair of treatments analyzed. The SUCRA ranking results show that some corneal surface ablation techniques (PRK and LASEK) rank highest. CONCLUSIONS This network meta-analysis shows that there were no statistically significant differences in either visual outcomes (efficacy and safety) or visual quality (HOAs and CS). FS-LASIK behaved better in predictability than any other type of surgeries.
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Pahuja NK, Shetty R, Deshmukh R, Sharma A, Nuijts RMMA, Jhanji V, Sethu S, Ghosh A. In vivo confocal microscopy and tear cytokine analysis in post-LASIK ectasia. Br J Ophthalmol 2017; 101:1604-1610. [PMID: 28450380 DOI: 10.1136/bjophthalmol-2016-309142] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2016] [Revised: 01/23/2017] [Accepted: 03/21/2017] [Indexed: 11/03/2022]
Abstract
AIM Corneal keratectasia is one of the complications associated with laser in situ keratomileusis (LASIK) that results in vision impairment. The pathogenesis of post-LASIK ectasia (PLE) remains underexplored. We report the tear cytokine profile and in vivo confocal microscopy (IVCM) findings in eyes with PLE. METHODS This retrospective study included age-matched 7 (14 eyes) post-LASIK controls (PLCs) and 6 (12 eyes) PLE subjects. Corneal topography was used to categorise the subjects into PLC and PLE groups. Ocular Surface Disease Index (OSDI) scores obtained were based on standard questionnaire and IVCM images were used to determine corneal dendritic cells density (DCD) and sub-basal nerve plexus morphology. Inflammatory cytokines/chemokines in the tears were quantified using flow cytometry based cytometric bead array. RESULTS Pentacam-based scores, OSDI scores and corneal DCD were significantly (p<0.05) higher in patients with PLE compared with PLC. Discomfort-related subscale of OSDI score exhibited a positive correlation with total corneal DCD in the PLE cohort. The fold difference of chemokine (C-C motif) ligand/monocyte chemotactic protein-1 (CCL2/MCP1) (3.4±0.6) was found to be significantly (p<0.05) higher in the PLE cohorts and a positive correlation between CCL2/MCP1 levels and total corneal DCD was also observed in the PLE cohort. CONCLUSION The current study found a significant difference in the tear film cytokine profile between normal and PLE eyes. Presence of increased corneal dendritic cells and altered tear cytokines suggests an ongoing inflammatory response in PLE.
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Affiliation(s)
| | - Rohit Shetty
- Cornea and Refractive Services, Narayana Nethralaya, Bangalore, India
| | - Rashmi Deshmukh
- Cornea and Refractive Services, Narayana Nethralaya, Bangalore, India
| | - Anupam Sharma
- Narayana Nethralaya Foundation, GROW Research Laboratory, Bangalore, India
| | - Rudy M M A Nuijts
- Cornea Clinic, Department of Ophthalmology, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Vishal Jhanji
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.,UPMC Eye Center, University of Pittsburgh School of Medicine, Pittsburgh, USA
| | - Swaminathan Sethu
- Narayana Nethralaya Foundation, GROW Research Laboratory, Bangalore, India
| | - Arkasubhra Ghosh
- Narayana Nethralaya Foundation, GROW Research Laboratory, Bangalore, India.,Singapore Eye Research Institute, Singapore
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Vahdati A, Seven I, Mysore N, Randleman JB, Dupps WJ. Computational Biomechanical Analysis of Asymmetric Ectasia Risk in Unilateral Post-LASIK Ectasia. J Refract Surg 2016; 32:811-820. [PMID: 27930791 DOI: 10.3928/1081597x-20160929-01] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Accepted: 08/29/2016] [Indexed: 11/20/2022]
Abstract
PURPOSE To develop a computational approach to corneal biomechanical risk analysis in refractive surgery and to investigate its utility in an enigmatic case of unilateral ectasia after bilateral LASIK. METHODS Preoperative corneal elevation datasets from both eyes of a patient who developed unilateral post-LASIK ectasia were used to construct geometrically patient-specific, microstructurally motivated finite element models. Models were assessed before and after implementation of case-specific treatment parameters for interocular differences in corneal geometry and strain behavior under physiological loading conditions. RESULTS Standard clinical predictors of post-LASIK ectasia risk were similar for the affected and contralateral eyes, and no risk factor asymmetry was identified in tomographic screening that included posterior corneal elevation analysis. However, differences in the magnitude and distribution of strain and stress were observed that are consistent with greater predisposition to biomechanical instability in the affected eye. Load testing with simulated intraocular pressure increases provoked opposite trends in curvature change in the preoperative models representing affected and unaffected eyes, with steepening in the ectatic eye and flattening in the clinically stable eye. CONCLUSIONS Patient-specific computational analyses revealed differences in intrinsic biomechanical behaviors that may predispose a cornea to instability after refractive surgery. Strain and stress analyses elucidated differential risk not ascertained with current refractive surgery screening paradigms. This pilot study illustrates a risk analysis approach that implicitly considers the entire corneal three-dimensional geometry and can be performed a priori in a screening setting. [J Refract Surg. 2016;32(12):811-820.].
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Normative values and contralateral comparison of anterior chamber parameters measured by Pentacam and its correlation with corneal biomechanical factors. Saudi J Ophthalmol 2016; 31:7-10. [PMID: 28337056 PMCID: PMC5352957 DOI: 10.1016/j.sjopt.2016.11.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 11/14/2016] [Accepted: 11/22/2016] [Indexed: 11/21/2022] Open
Abstract
PURPOSE To evaluate the normative values of anterior chamber parameters measured by Pentacam and corneal hysteresis (CH) and corneal resistance factor (CRF) measured by Ocular Response Analyzer (ORA) and their relationship. METHODS In an observational cross-sectional study, patients aged 18-35 years were included. Exclusion criteria were history of any intraocular or corneal disease, anomaly or surgery; hyperopic spherical refraction more than +3, and myopic spherical refraction less than -5.00 diopters (D) or cylindrical refraction more than 2.00 D. ORA was used to measure CH and CRF. Corneal volume (CV), anterior and posterior Q value (QA and QP), anterior and posterior elevation (AE and PE), central corneal thickness (CCT), corneal thinnest thickness (CTT), anterior chamber depth (ACD), anterior chamber volume (ACV) and anterior chamber angle (ACA) were measured with Pentacam. RESULTS This study evaluated 506 eyes of 253 cases (182 females) with a mean age of 28.43 ± 6.36 years. The average CH and CRF were 10.07 ± 1.61 and 10.33 ± 1.68 mmHg. CH and CRF were not correlated with PQ, AQ, AE and PE. CH and CRF were significantly correlated with CCT (r = 0.499, p < 0.0001 and r = 0.591, p < 0.0001 respectively), CTT (r = 0.469, p < 0.0001 and r = 0.593, p < 0.0001 respectively) and CV (r = 0.443, p < 0.0001 and r = 0.526, p < 0.0001 respectively). CONCLUSION A significant positive correlation was found between CH and CRF, and CCT, CTT and CV. This study also provided data about wide range normative values of corneal parameters.
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Subclinical keratoconus detection by pattern analysis of corneal and epithelial thickness maps with optical coherence tomography. J Cataract Refract Surg 2016; 42:284-95. [PMID: 27026454 DOI: 10.1016/j.jcrs.2015.09.021] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 08/22/2015] [Accepted: 09/01/2015] [Indexed: 11/24/2022]
Abstract
PURPOSE To screen for subclinical keratoconus by analyzing corneal, epithelial, and stromal thickness map patterns with Fourier-domain optical coherence tomography (OCT). SETTING Four centers in the United States. DESIGN Cross-sectional observational study. METHODS Eyes of normal subjects, subclinical keratoconus eyes, and the topographically normal eye of a unilateral keratoconus patient were studied. Corneas were scanned using a 26,000 Hz Fourier-domain OCT system (RTVue). Normal subjects were divided into training and evaluation groups. Corneal, epithelial, and stromal thickness maps and derived diagnostic indices, including pattern standard deviation (PSD) variables and pachymetric map-based keratoconus risk scores, were calculated from the OCT data. Area under the receiver operating characteristic curve (AUC) analysis was used to evaluate the diagnostic accuracy of the indices. RESULTS The study comprised 150 eyes of 83 normal subjects, 50 subclinical keratoconus eyes of 32 patients, and 1 topographically normal eye of a unilateral keratoconus patient. Subclinical keratoconus was characterized by inferotemporal thinning of the cornea, epithelium, and stroma. The PSD values for corneal (P < .001), epithelial (P < .001), and stromal (P = .049) thickness maps were all significantly higher in subclinical keratoconic eyes than in the normal group. The diagnostic accuracy was significantly higher for PSD variables (pachymetric PSD, AUC = 0.941; epithelial PSD, AUC = 0.985; stromal PSD, AUC = 0.924) than for the pachymetric map-based keratoconus risk score (AUC = 0.735). CONCLUSIONS High-resolution Fourier-domain OCT could map corneal, epithelial, and stromal thicknesses. Corneal and sublayer thickness changes in subclinical keratoconus could be detected with high accuracy using PSD variables. These new diagnostic variables might be useful in the detection of early keratoconus. FINANCIAL DISCLOSURES Oregon Health and Science University (OHSU) and Drs. Li, Tan, and Huang have a significant financial interest in Optovue, Inc. These potential conflicts have been reviewed and managed by OHSU. Dr. Brass receives research grants from Optovue, Inc. Drs. Chamberlain and Weiss have no financial or proprietary interest in any material or method mentioned.
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Rotating Scheimpflug Imaging Indices in Different Grades of Keratoconus. J Ophthalmol 2016; 2016:6392472. [PMID: 27579178 PMCID: PMC4992767 DOI: 10.1155/2016/6392472] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 06/26/2016] [Accepted: 07/10/2016] [Indexed: 11/17/2022] Open
Abstract
Purpose. To evaluate accuracy of various Keratoconus (KC) screening indices, in relation to Topographic Keratoconus (TKC) grading. Setting. Al Watany Eye Hospital, Cairo, Egypt. Methods. Data of 103 normal (group 1) and 73 KC eyes (group 2), imaged by Pentacam (branded as Allegro Oculyzer), were analysed. Group 2 was divided into 2a: 14 eyes (TKC = 1, early KC), 2b: 25 eyes (TKC = 1 to 2 or 2, moderate KC), and 2c: 34 eyes (TKC = 2 to 3 up to 4, severe KC). Participants were followed up for six years to confirm diagnosis. Area under the receiver operating characteristic curve (AUROC) was calculated for evaluated curvature, elevation, and pachymetry indices with various reference shapes at different diameters. Results. When comparing normal to KC eyes, ten indices had significantly higher AUROC. Only five of them had significantly higher AUROC in early KC compared to normal corneas: Pachymetry Progression Index- (PPI-) Maximum (Max), Ambrósio's Relational Thickness- (ART-) Max, PPI-Max minus PPI-Minimum (Min), central corneal thickness (CCT), and diagonal decentration of thinnest point from the apex (AUROC = 0.690, 0.690, 0.687, 0.683, and 0.674, resp.). Conclusion. Generally, ten pachymetry and elevation-based indices had significantly higher AUROC. Five indices had statistically significant high AUROC when comparing early KC to normal corneas.
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Detection of ectatic corneal diseases based on pentacam. Z Med Phys 2016; 26:136-42. [DOI: 10.1016/j.zemedi.2015.11.001] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 11/13/2015] [Accepted: 11/13/2015] [Indexed: 11/20/2022]
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Luz A, Lopes B, Salomão M, Ambrósio R. Application of corneal tomography before keratorefractive procedure for laser vision correction. JOURNAL OF BIOPHOTONICS 2016; 9:445-453. [PMID: 27079610 DOI: 10.1002/jbio.201500236] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 01/29/2016] [Accepted: 02/21/2016] [Indexed: 06/05/2023]
Abstract
Ectasia after refractive surgery represents a major concern among refractive surgeons. Corneal abnormalities and preexisting corneal ectasia are the most important risk factors. Corneal topography and central corneal thickness are the factors traditionally screening for in refractive surgery candidates. Study of the anterior surface by Placido topography allows for identification of keratoconus before biomicroscopy. However, this is insufficient for the evaluation of pre-operative refractive surgery. There are cases of ectasia after laser in situ keratomilusis (LASIK) without identifiable risk factors such that there is a need to go beyond the corneal surface. A key requirement is quantifying susceptibility to corneal biomechanical instability and progression to ectasia. Tomographic indices derived from elevation maps and pachymetry spatial variation produce a Belin Ambrosio display final D index (BAD-D index), which has shown better results compared to surface curvature indices for detecting very mild forms of ectasia. A logistic regression formula, integrating age, residual stromal bed, and BAD-D (Ectasia Susceptibility Score, ESS) resulted in a significant improvement in accuracy, leading to 100% sensitivity and 94% specificity for detecting susceptible cases. A comprehensive corneal structural analysis based on corneal segmental tomography can detect susceptible corneas, which increases safety for refractive surgery patients.
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Affiliation(s)
- Allan Luz
- Department of Ophthalmology of the Federal University of Sao Paulo, Sao Paulo, Brazil.
- Cornea and Refractive Surgery Department, Hospital de Olhos de Sergipe, Aracaju, Brazil.
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil.
| | - Bernardo Lopes
- Department of Ophthalmology of the Federal University of Sao Paulo, Sao Paulo, Brazil
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
| | - Marcela Salomão
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
| | - Renato Ambrósio
- Department of Ophthalmology of the Federal University of Sao Paulo, Sao Paulo, Brazil
- Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil
- Instituto de Olhos Renato Ambrósio and Visare Personal Laser Rio de Janeiro, Rio de Janeiro, Brazil
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Effect of Flat Cornea on Visual Outcome after LASIK. J Ophthalmol 2015; 2015:794854. [PMID: 26693347 PMCID: PMC4677010 DOI: 10.1155/2015/794854] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Revised: 11/08/2015] [Accepted: 11/10/2015] [Indexed: 11/17/2022] Open
Abstract
Purpose. To evaluate the effect of preoperative and postoperative keratometry on the refractive outcome after laser in situ keratomileusis (LASIK) for moderate and high myopia. Methods. Records of 812 eyes (420 patients) with myopia ≥−6 D who had LASIK at Sohag Laser Center, Egypt, from January 2010 to November 2013, were retrospectively analyzed. Main outcome measures were postoperative corrected distance visual acuity (CDVA), postoperative spherical equivalence, and postoperative Q factor. Results. LASIK was performed in 812 eyes (mean age 21.8 ± 5.2 years). Patients were grouped according to the degree of preoperative myopia into three groups: Group 1, −6 D to −7.9 D; Group 2, −8 to −9.9 D; and Group 3, −10 to −12 D. The refractive outcome among the different myopia groups was stratified by pre- and postoperative keratometry. A trend toward greater undercorrection was noted in eyes with preoperative keratometry <43.5 D compared with those with steeper keratometry >46 D in all myopia groups. The undercorrection was also noted in postoperative keratometry groups <35 D. Conclusions. Preoperative and postoperative keratometry appeared to influence the refractive outcome especially in high myopic eyes.
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Zhang X, Yin Y, Guo Y, Fan N, Lin H, Liu F, Diao X, Dong C, Chen X, Wang T, Chen S. Measurement of quantitative viscoelasticity of bovine corneas based on lamb wave dispersion properties. ULTRASOUND IN MEDICINE & BIOLOGY 2015; 41:1461-72. [PMID: 25638310 DOI: 10.1016/j.ultrasmedbio.2014.12.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2014] [Revised: 12/11/2014] [Accepted: 12/15/2014] [Indexed: 05/04/2023]
Abstract
The viscoelastic properties of the human cornea can provide valuable information for clinical applications such as the early detection of corneal diseases, better management of corneal surgery and treatment and more accurate measurement of intra-ocular pressure. However, few techniques are capable of quantitatively and non-destructively assessing corneal biomechanics in vivo. The cornea can be regarded as a thin plate in which the vibration induced by an external vibrator propagates as a Lamb wave, the properties of which depend on the thickness and biomechanics of the tissue. In this study, pulses of ultrasound radiation force with a repetition frequency of 100 or 200 Hz were applied to the apex of corneas, and the linear-array transducer of a SonixRP system was used to track the tissue motion in the radial direction. Shear elasticity and viscosity were estimated from the phase velocities of the A0 Lamb waves. To assess the effectiveness of the method, some of the corneas were subjected to collagen cross-linking treatment, and the changes in mechanical properties were validated with a tensile test. The results indicated that the shear modulus was 137 ± 37 kPa and the shear viscosity was 3.01 ± 2.45 mPa · s for the group of untreated corneas and 1145 ± 267 kPa and was 0.16 ± 0.11 mPa · s for the treated group, respectively, implying a significant increase in elasticity and a significant decrease in viscosity after collagen cross-linking treatment. This result is in agreement with the results of the mechanical tensile test and with reports in the literature. This initial investigation illustrated the ability of this ultrasound-based method, which uses the velocity dispersion of low-frequency A0 Lamb waves, to quantitatively assess both the elasticity and viscosity of corneas. Future studies could discover ways to optimize this system and to determine the feasibility of using this method in clinical situations.
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Affiliation(s)
- Xinyu Zhang
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China
| | - Yin Yin
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China
| | - Yanrong Guo
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China
| | - Ning Fan
- Shenzhen Key Laboratory of Ophthalmology, Shenzhen Eye Hospital, Jinan University, Shenzhen, People's Republic of China
| | - Haoming Lin
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China
| | - Fulong Liu
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China
| | - Xianfen Diao
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China
| | - Changfeng Dong
- Department of Ultrasonography, Third People's Hospital of Shenzhen, Shenzhen, People's Republic of China
| | - Xin Chen
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China.
| | - Tianfu Wang
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China
| | - Siping Chen
- National-Regional Key Technology Engineering Laboratory for Medical Ultrasound, Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging, School of Medicine, Shenzhen University, Shenzhen, People's Republic of China
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Air-pulse corneal applanation signal curve parameters for characterization of astigmatic corneas. Cornea 2015; 33:721-5. [PMID: 24886996 DOI: 10.1097/ico.0000000000000153] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE The aim of this study was to test the 42 parameters of the ocular response analyzer for distinguishing between the biomechanical properties of emmetropic eyes with normal topography and eyes with moderate-to-high with-the-rule astigmatism (WTA) and against-the-rule astigmatism (ATA) that have symmetric bowtie topography. METHODS This retrospective case series study included 37 patients (37 studied eyes) with WTA astigmatism and 35 patients (35 studied eyes) with ATA astigmatism. The control group consisted of 70 patients with emmetropia (70 studied eyes) with normal topography. We first tested correlations of the parameters that describe the applanation curve during ocular response analyzer measurements with the maximum keratometry values and the corneal thickness in all 3 groups. We then evaluated the significant parameters among them in search of any group differences in the biomechanical properties of the cornea. RESULTS Fifteen parameters correlated with Kmax reading values or corneal thickness values. The correlation coefficients (r) were low. The best correlated parameters were p1area, p2area, h1, dive1, p2area1, h11, h2, and h21. The ATA group had the highest number of parameters (n = 6) with significant differences compared with the control group. Only p2area was predictive for ATA. In contrast, the WTA group had only 1 parameter (p2area1) that was found to be significantly different compared with the control group. CONCLUSIONS Some of the new waveform parameters can distinguish between patients with ATA and WTA and normal topography patterns and may delineate the differences in biomechanical properties between these groups that may predict the risk of corneal ectasia after laser in situ keratomileusis.
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