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Al Bdour M, Sabbagh HM, Jammal HM. Multi-modal imaging for the detection of early keratoconus: a narrative review. EYE AND VISION (LONDON, ENGLAND) 2024; 11:18. [PMID: 38730479 PMCID: PMC11088107 DOI: 10.1186/s40662-024-00386-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 04/21/2024] [Indexed: 05/12/2024]
Abstract
Keratoconus is a common progressive corneal disorder that can be associated with significant ocular morbidity. Various corneal imaging techniques have been used for the diagnosis of established cases. However, in the early stages of the disease, which include subclinical keratoconus and forme fruste keratoconus, detection of such cases can be challenging. The importance of detecting such cases is very important because early intervention can halt disease progression, improve visual outcomes and prevent postrefractive surgery ectasia associated with performing corneal refractive procedures in such patients. This narrative review aimed to examine several established and evolving imaging techniques for the detection of early cases of keratoconus. The utilization of combinations of these techniques may further increase their diagnostic ability.
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Affiliation(s)
- Muawyah Al Bdour
- Department of Ophthalmology, School of Medicine, The University of Jordan, Amman, Jordan
| | - Hashem M Sabbagh
- The National Center for Diabetes Endocrinology and Genetics (NCDEG), Amman, Jordan
| | - Hisham M Jammal
- Department of Ophthalmology, Faculty of Medicine, Jordan University of Science and Technology, PO Box 3030, Irbid, 22110, Jordan.
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Moshirfar M, Pandya S, Zhang S, Stoakes IM, Ayesha A, Hoopes PC. AvaGen Genetic Testing versus Ocular Screening Assessments Including the Keratoconus Severity Score (KSS) and Randleman Ectasia Risk Score System (ERSS) in Refractive Surgery Candidates. Clin Ophthalmol 2024; 18:1245-1255. [PMID: 38737593 PMCID: PMC11088376 DOI: 10.2147/opth.s452128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 04/15/2024] [Indexed: 05/14/2024] Open
Abstract
Purpose To determine whether the AvaGen (AG) Genetic Eye Test provided additional information for screening for the presence of keratoconus (KC) and assessing KC risk in refractive surgery candidates, as compared to the Keratoconus Severity Score (KSS) and Randleman Ectasia Risk Score System (ERSS). Methods This retrospective study analyzed patients seeking refractive surgery at an eye clinic in the United States between January 2022 and July 2023. The inclusion criteria encompassed those with a family history of KC, positive KC indices, or both. Corneal evaluations and demographic information were recorded and analyzed. KSS and ERSS criteria were utilized to evaluate postoperative KC and ectasia risk, respectively. Patients were categorized on how the AG genetic test compared to KSS and ERSS criteria. Clinicians assessed topographic indices, criteria scoring, and AG testing to deliver a definitive surgical recommendation. Results Among the 19 patients evaluated for ectasia risk, AG testing showed lower KC risk than ocular screening in three patients (15.8%), equal risk in three patients (15.8%), and higher risk in 13 patients (68.4%). The mean AG scores were 45.7 ± 7.0, 49.0 ± 3.46, and 61 ± 13.0 for these respective categories. The most frequently identified KC risk genes were ADAMTS18, COL2A1, and COL4A1. The AG test modified the physician's recommendation for refractive surgery in nine cases (47.4%). Conclusion Despite the promising application of AG testing for assessing KC risk, further research and development are needed to enhance its applicability for screening refractive surgery candidates, in addition to standard ocular screening approaches.
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Affiliation(s)
- Majid Moshirfar
- Hoopes Vision Research Center, Hoopes Vision, Draper, UT, USA
- John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT, USA
- Utah Lions Eye Bank, Murray, UT, USA
| | - Shreya Pandya
- University of Louisville School of Medicine, Louisville, KY, USA
| | - Stephanie Zhang
- University of Arizona College of Medicine-Phoenix, Phoenix, AZ, USA
| | - Isabella M Stoakes
- Hoopes Vision Research Center, Hoopes Vision, Draper, UT, USA
- Pacific Northwest University of Health Sciences, Yakima, WA, USA
| | - Azraa Ayesha
- University of Utah School of Medicine, Salt Lake City, UT, USA
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Chauhan P, Kamalakannan P, Upadhyay AD, Sinha R, Titiyal JS, Sharma N. Comparative Evaluation of Topographic Parameters Using Three Different Topographers in Keratoconic and Cross-linked Keratoconic Corneas. J Refract Surg 2024; 40:e260-e269. [PMID: 38593263 DOI: 10.3928/1081597x-20240311-07] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
PURPOSE To compare the parameters of three different topographic devices (Pentacam HR, Oculus Optikgeräte GmbH; Sirius, Costruzione Strumenti Oftalmici; and Cassini, i-Optics) in grading the severity of keratoconus in cross-linked and non-cross-linked eyes. METHODS This was a prospective comparative interventional study done in a tertiary eye care center, wherein 114 eyes of 68 patients with keratoconus were divided into two groups: 62 eyes that were observed and 52 eyes that were cross-linked. All eyes were evaluated on all three topographers at baseline, 3-month follow-up, and 6-month follow-up. RESULTS The Sirius showed significantly lower values of mean flat keratometry in comparison to the Pentacam HR (limits of agreement [LoA]: 1.75 to 3.51%) and Cassini (LoA: 1.75 to 3.51%). The mean steep keratometry values were higher for the Cassini in comparison to the Pentacam HR (LoA: 4.39 to 7.02%) and Sirius (LoA: 3.51 to 6.14%). The mean steep keratometry values of the Sirius were significantly lower than those of the Pentacam HR and in both the cross-linked and observation groups (LoA: 3.51 to 6.14%). The mean keratometry values were significantly higher in the Cassini compared to the Pentacam HR (LoA: 3.51 to 8.77%) and significantly lower in the Sirius in comparison to the Pentacam HR (LoA: 3.51 to 6.14%). The mean difference in astigmatism was also statistically significant between the three tomographers in both groups, with the Cassini showing higher values (LoA: 3.51 to 5.26%) and the Sirius lower values than the Pentacam HR (LoA: 5.26 to 6.14%). CONCLUSIONS The authors conclude the three devices cannot be used interchangeably. The Cassini showed better agreement and correlation with the Pentacam HR in the staging of keratoconus, whereas the Sirius tended to underdiagnose and under-stage the disease. [J Refract Surg. 2024;40(4):e260-e269.].
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Catania F, Vinciguerra P, Di Maria A. Low Rate of Postoperative Pterygium Recurrence in Patients under Treatment with Low-Dose Oral Doxycycline for Chronic Blepharitis: A First Report. Diagnostics (Basel) 2024; 14:715. [PMID: 38611627 PMCID: PMC11012025 DOI: 10.3390/diagnostics14070715] [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: 12/27/2023] [Revised: 03/02/2024] [Accepted: 03/21/2024] [Indexed: 04/14/2024] Open
Abstract
PURPOSE Low doses of systemic doxycycline (LD-SD) inhibit angiogenesis and the expression of matrix metalloproteases, which are determinants of pterygium progression. This study aimed to compare the recurrence rate and visual outcome of pterygium excision in patients undergoing chronic treatment with LD-SD for chronic refractory blepharitis and LD-SD-naive patients. METHODS A retrospective analysis of patients that underwent surgical excision and conjunctival graft apposition was conducted. Patients were divided in a TETRA group (under LD-SD treatment at the moment of surgery) and a control group. The main outcome was the rate of recurrence at 1 year postoperatively. Secondary outcomes were the comparisons of surface regularity, visual quality, and dry-eye symptoms at 6-week, 6-month, and 1-year follow-up in the two groups. RESULTS The TETRA group showed a significantly lower rate of 1-year recurrence both in primary (p = 0.034) and recurrent (p < 0.001) pterygia. The best corrected visual acuity (BCVA), astigmatic error, corneal total root mean square (RMS), and ocular surface disease index (OSDI) significantly reduced during the follow-up in both groups. The surface asymmetry index and high-order aberrations (HOAs) significantly reduced only in the TETRA group. The final BCVA was significantly higher, while the OSDI score and total RMS and HOAs were significantly lower in the TETRA group compared to the control. CONCLUSIONS Patients under treatment with LD-SD showed a lower rate of recurrence at 1-year follow-up compared to controls. These patients also experienced higher BCVA and surface regularity and less dry-eye symptoms.
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Affiliation(s)
- Fiammetta Catania
- Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, 20072 Pieve Emanuele, Italy;
- IRCCS Humanitas Research Hospital, via Manzoni 56, 20089 Rozzano, Italy;
| | - Paolo Vinciguerra
- Department of Biomedical Sciences, Humanitas University, Via Rita Levi Montalcini 4, 20072 Pieve Emanuele, Italy;
- IRCCS Humanitas Research Hospital, via Manzoni 56, 20089 Rozzano, Italy;
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Bajtl D, Bjeloš M, Bušić M, Ćurić A, Biuk D, Barać J. Corneal Fourier and Belin-Ambrósio Enhanced Ectasia Analysis in Healthy 4-Year-Old White Children. Cornea 2024; 43:59-62. [PMID: 36728315 DOI: 10.1097/ico.0000000000003236] [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: 11/16/2022] [Accepted: 12/06/2022] [Indexed: 02/03/2023]
Abstract
PURPOSE The aim of this study was to provide normative databases of Fourier analysis (FA) and Belin-Ambrósio enhanced ectasia display (BAD) in healthy White 4-year-old emmetropic children. METHODS FA parameters analyzed were spherical component (SRmin), spherical eccentricity (SEcc), maximal decentration (MD), regular astigmatism at the center (Astigm. C) and periphery (Astigm. P), and irregularity (I). The parameters obtained by BAD included summary indicator BAD D, anterior corneal curvature (K1 and K2, D), maximal keratometry (Kmax, D), maximal Ambrósio relational thinnest (ART max), and pachymetric and BAD indices. RESULTS Eighty-nine eyes of eighty-nine 4-year-old children were included. The mean values of FA parameters were the following: SRmin 7.77, SEcc 0.600, MD 0.160, Astigm. C 0.070, Astigm. P 0.050, and I 0.019. The mean K1 and K2 in our study group were 42.92 ± 1.29 D and 43.75 ± 1.41 D, with the mean BAD D value 0.42 ± 0.67. The mean PPI min 0.629 ± 0.117, PPI max 1.059 ± 0.155, PPI avg 0.847 ± 0.103, Kmax 44.10 ± 1.39, and median of ART max 515.0 were recorded. No statistically significant differences between male and female sex in any of FA or BAD parameters were found. CONCLUSIONS This is the first study providing large normative data on FA and BAD in 4-year-old White emmetropic children. We proposed a cutoff D value for early ectasia and clinical keratoconus in 4-year-old children.
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Affiliation(s)
- Dunja Bajtl
- University Eye Department, University Hospital Centre Osijek
| | - Mirjana Bjeloš
- Faculty of Medicine, Josip Juraj Strossmayer University of Osijek
- University Eye Department, Reference Centre of the Ministry of Health of the Republic of Croatia for Paediatric Ophthalmology and Strabismus, Reference Centre of the Ministry of Health of the Republic of Croatia for Inherited Retinal Dystrophies University Hospital "Sveti Duh", Zagreb ; and
- Faculty of Dental Medicine and Health Osijek, Josip Juraj Strossmayer University of Osijek, Croatia
| | - Mladen Bušić
- Faculty of Medicine, Josip Juraj Strossmayer University of Osijek
- University Eye Department, Reference Centre of the Ministry of Health of the Republic of Croatia for Paediatric Ophthalmology and Strabismus, Reference Centre of the Ministry of Health of the Republic of Croatia for Inherited Retinal Dystrophies University Hospital "Sveti Duh", Zagreb ; and
- Faculty of Dental Medicine and Health Osijek, Josip Juraj Strossmayer University of Osijek, Croatia
| | - Ana Ćurić
- University Eye Department, Reference Centre of the Ministry of Health of the Republic of Croatia for Paediatric Ophthalmology and Strabismus, Reference Centre of the Ministry of Health of the Republic of Croatia for Inherited Retinal Dystrophies University Hospital "Sveti Duh", Zagreb ; and
- Faculty of Dental Medicine and Health Osijek, Josip Juraj Strossmayer University of Osijek, Croatia
| | - Dubravka Biuk
- University Eye Department, University Hospital Centre Osijek
- Faculty of Medicine, Josip Juraj Strossmayer University of Osijek
| | - Josip Barać
- University Eye Department, University Hospital Centre Osijek
- Faculty of Medicine, Josip Juraj Strossmayer University of Osijek
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Yesilkaya EC, Ozyurek EBA, Dursun T, Dirim AB, Turker IC, Demir ST. The Effects of Blepharoptosis Surgery on Meibomian Gland, Tear Film, and Corneal Topography. BEYOGLU EYE JOURNAL 2023; 8:214-220. [PMID: 37766763 PMCID: PMC10521128 DOI: 10.14744/bej.2023.99266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 08/22/2023] [Accepted: 08/22/2023] [Indexed: 09/29/2023]
Abstract
Objectives The objective of this study was to evaluate the Meibomian gland (MG), tear film, and corneal changes in the post-operative period following ptosis surgery using corneal topography. Methods This non-comparative, case series study analyzed 30 eyes of 23 patients undergoing blepharoptosis surgery with an external approach. Ocular surface and tear film evaluation was performed at baseline and post-operative 3rd month. The corneal topography was used to assess the MG, the noninvasive tear film break-up time (NI-TBUT), K values, astigmatism, and corneal aberrations. For the examination of dry eyes, the I-TBUT, Schirmer, and ocular surface disease index (OSDI) questionnaires were also performed. Results The study involved patients with a mean age of 55.1±18.11 years. Postoperatively, marginal reflex distance 1 is significantly increased (1.23±1.09 vs. 3.65±0.65; p=0.001). Results revealed no significant changes in Kmean (43.65±1.15 vs. 43.67±1.14; p=0.727), astigmatism (-1±0.74 vs. -0.99±0.68; p=0.910), and corrected distance visual acuity logMAR (0.09±0.1 vs. 0.07±0.11; p=0.497). There was a significant increase in MG loss area postoperatively (5.02±5.04-7.75±6.75; p=0.047), while the degree of MG loss did not significantly change (0.2±0.48 vs. 0.37±0.56; p=0.132). However, no significant differences were detected in Schirmer I test (17.4±4.7 vs. 16.1±5.5; p=0.711), I-TBUT (12.4±3.1 vs. 11.9±4.7; p=0.483), and OSDI questionnaire score (16.7±9.4 vs. 17.9±10.3; p=0.176) between baseline and post-operative measurements. Similarly, no significant changes were found in NI-TBUT (5.73±3.72 vs. 6.58 4.71; p=0.535) and NIAvg-TBUT (6.06±4.8 vs. 7.51±4.43; p=0.322) values. Conclusion Surgical correction of blepharoptosis affects MG morphology without causing dry eye at the 3rd month. Post-operative corneal topography is useful in demonstrating changes in the MG.
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Affiliation(s)
- Elif Ceren Yesilkaya
- Health Sciences University, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Türkiye
| | | | - Tugce Dursun
- Health Sciences University, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Türkiye
| | - Ayse Burcu Dirim
- Health Sciences University, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Türkiye
| | - Ibrahim Cagri Turker
- Health Sciences University, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Türkiye
| | - Semra Tiryaki Demir
- Health Sciences University, Sisli Hamidiye Etfal Training and Research Hospital, Istanbul, Türkiye
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Abdi S, Hosseini Abardeh M, Naseri MH, Kamary Rad Z, Naghdi T. Measuring the agreement of keratometry readings of four devices in eyes with keratoconus. Int Ophthalmol 2023; 43:2897-2915. [PMID: 37060496 DOI: 10.1007/s10792-023-02693-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Accepted: 03/11/2023] [Indexed: 04/16/2023]
Abstract
PURPOSE To determine the keratometry measurement agreement using Sirius corneal topography and Scheimpflug camera, Tomey corneal topography, Topcon autokeratorefractometer, and Tomey OA-2000 optical biometry in eyes with different severity of keratoconus. METHODS In this retrospective study 115 eyes in different stages of keratoconus were divided into 2 groups of mild (stage 1), and moderate to severe keratoconus (stages 2, 3), according to the Amsler-Krumeich classification. Keratometry measurements were obtained using Sirius corneal topography and Scheimpflug camera (phoenix V3.7.01.08), Tomey corneal topography (Tms SW22C-200S-200), Topcon autokeratorefractometer (KR8900), and Tomey optical biometry (OA-2000 Opt-Meas V.4E). RESULTS In group 1 All devices demonstrated fair agreement in average keratometry values (95% LoA range > 1 D). However, it was poorer for group 2 (95% LOA range > 3 D). In group 1 Bonferroni test revealed statistically significant difference in average K readings among (Topcon autokeratorefractometer 8900 and Tomey OA-2000 biometry, p < 0.01), and between (Tomey topography and Topcon autokeratorefractometer, p < 0.05). Also in group 2 significant difference was observed in the average keratometry of the most instruments (p < 0.01) except for the (Tomey topography and Topcon autokeratorefractometer) and (Tomey topography and Tomey OA-2000 biometry. CONCLUSIONS According to our investigation in mild, moderate and severe keratoconus the agreement in K reading between Topcon autokeratorefractometer, OA-2000 optical biometry, Sirius topography and Tomey topography was poor. The agreement declines especially in the steep meridian and it was not acceptable clinically. These devices should not be applied interchangeably.
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Affiliation(s)
- Saeid Abdi
- Department of Optometry, Faculty of Rehabilitation, School of Rehabilitation, Shahid Beheshti University of Medical Sciences, Damavand Street, Tehran, Iran
| | - Mohsen Hosseini Abardeh
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mohammad Hashem Naseri
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Zahra Kamary Rad
- Department of Optometry, Faculty of Rehabilitation, School of Rehabilitation, Shahid Beheshti University of Medical Sciences, Damavand Street, Tehran, Iran.
| | - Taghi Naghdi
- Department of Optometry, Faculty of Rehabilitation, School of Rehabilitation, Shahid Beheshti University of Medical Sciences, Damavand Street, Tehran, Iran
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Fassbind B, Langenbucher A, Streich A. Automated cornea diagnosis using deep convolutional neural networks based on cornea topography maps. Sci Rep 2023; 13:6566. [PMID: 37085580 PMCID: PMC10121572 DOI: 10.1038/s41598-023-33793-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2022] [Accepted: 04/19/2023] [Indexed: 04/23/2023] Open
Abstract
Cornea topography maps allow ophthalmologists to screen and diagnose cornea pathologies. We aim to automatically identify any cornea abnormalities based on such cornea topography maps, with focus on diagnosing keratoconus. To do so, we represent the OCT scans as images and apply Convolutional Neural Networks (CNNs) for the automatic analysis. The model is based on a state-of-the-art ConvNeXt CNN architecture with weights fine-tuned for the given specific application using the cornea scans dataset. A set of 1940 consecutive screening scans from the Saarland University Hospital Clinic for Ophthalmology was annotated and used for model training and validation. All scans were recorded with a CASIA2 anterior segment Optical Coherence Tomography (OCT) scanner. The proposed model achieves a sensitivity of 98.46% and a specificity of 91.96% when distinguishing between healthy and pathological corneas. Our approach enables the screening of cornea pathologies and the classification of common pathologies like keratoconus. Furthermore, the approach is independent of the topography scanner and enables the visualization of those scan regions which drive the model's decisions.
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Affiliation(s)
- Benjamin Fassbind
- Department of Computer Science, Lucerne University of Applied Sciences and Arts, Rotkreuz/Zug, 6343, Switzerland.
| | - Achim Langenbucher
- Department of Experimental Ophthalmology, Saarland University, Homburg/Saar, 66123, Germany
| | - Andreas Streich
- Department of Computer Science, Lucerne University of Applied Sciences and Arts, Rotkreuz/Zug, 6343, Switzerland
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Fikret CZ, Ucgun NI, Karaca EE, Kemer OE. Corneal characteristics in patients with Retinitis Pigmentosa. Photodiagnosis Photodyn Ther 2023; 42:103554. [PMID: 37030435 DOI: 10.1016/j.pdpdt.2023.103554] [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: 02/12/2023] [Revised: 04/03/2023] [Accepted: 04/03/2023] [Indexed: 04/10/2023]
Abstract
BACKGROUND To evaluate corneal topography and specular microscopic findings in patients with retinitis pigmentosa. METHODS One hundred and two eyes of 51 patients with retinitis pigmentosa and 60 eyes of 30 healty subjects were included in our study. A detailed ophthalmological examination involving best corrected visual acuity (BCVA) was performed. A rotating Scheimpflug imaging system, was used to evaluate all eyes for topographic and aberrometrics parameters. Specular microscopy measurements were also noted. RESULTS The retinitis pigmentosa group consisted of 51 patients (29 male and 22 female, mean age of 35.61±13.55 (18-65) years and the control group also consisted of 30 healty subjects (29 male and 22 female, mean age of 33.67±9.92 (20-58) years. There was no difference between the groups in terms of age (p=0.624) and gender (p=0.375). Spherical equivalents were higher in the RP group (p<0.001). Central keratoconus index (CKI) (p<0.001), Belin Ambrosio enhanced ectasia display total deviation value (BAD-D) (p=0.003), index of surface variance (ISV) (p<0.001), index of vertical asymmetry (IVA) (p<0.001), Ambrosio related thickness (ART max) (p=0.018), index of height asymmetry (IHA) (p=0.009), index of height decentration (IHD) (p<0.001), maximum anterior elevation (p<0.001), front elevation in thin location (p=0.05), progression index average (p=0.015), root mean square (RMS) total (p=0.010) and RMS-higher order aberration (RMS-HOA) (p<0.001) values were higher in RP group. There was a weak negative correlation between BCVA and ART max measurements (r=-0.256, p=0.009) in RP group. We detected keratoconus-suspect in 6 eyes and clinically manifest keratoconus in one eye in the RP group. CONCLUSIONS Patients with retinitis pigmentosa may have corneal morphological disorders that may affect vision. In our study, corneal topographic pathologies including keratoconus and possible keratoconus were detected in RP patients.
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Affiliation(s)
- Cenk Zeki Fikret
- Ankara City Hospital, Ankara, Turkey, Department of Ophthalmology.
| | - Nil Irem Ucgun
- University of Health Sciences, Ankara City Hospital, Ankara, Turkey, Department of Ophthalmology.
| | | | - Ozlem Evren Kemer
- University of Health Sciences, Ankara City Hospital, Ankara, Turkey, Department of Ophthalmology.
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Coskunseven E, Kayhan B. Asymmetric intracorneal ring segments in the treatment of snowman phenotype keratoconus. J Fr Ophtalmol 2023; 46:510-517. [PMID: 36890076 DOI: 10.1016/j.jfo.2022.11.012] [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: 09/04/2022] [Revised: 10/13/2022] [Accepted: 11/11/2022] [Indexed: 03/08/2023]
Abstract
OBJECTIVE To evaluate refractive, aberrometric, topographic, and topometric outcomes of asymmetric intracorneal ring segment (ICRS) implantation in snowman phenotype (asymmetric bow-tie) keratoconus. METHODS This retrospective, interventional study included eyes with snowman phenotype keratoconus. Two asymmetric ICRSs (Keraring AS) were implanted after femtosecond laser-assisted tunnel formation. Visual, refractive, aberrometric, topographic, and topometric changes after asymmetric ICRS implantation were evaluated with a mean follow-up of 11 months (6-24 months). MAIN RESULTS Seventy-one eyes were analyzed in the study. Keraring AS implantation corrected refractive errors significantly. The mean spherical error decreased from -5.06±4.23 D to -1.62±3.45 D (P=0.001), and the mean cylindrical error decreased from -5.43±2.48 D to -2.44±1.49 D (P=0.001). Uncorrected distance visual acuity improved from 0.98±0.80 to 0.46±0.46 Log MAR (P=0.001), and corrected distance visual acuity improved from 0.58±0.56 to 0.17±0.39 Log MAR (P=0.001). Keratometry (K) maximum, K1, K2, K mean, astigmatism, and corneal asphericity (Q-value) showed a significant decrease (P=0.001). Vertical coma aberration decreased significantly from -3.31±2.12μm to -2.56±1.94μm (P=0.001). All topometric indices of corneal irregularities were significantly reduced postoperatively (P=0.001). CONCLUSIONS Keraring AS implantation in snowman phenotype keratoconus demonstrated good efficacy and safety. Clinical, topographic, topometric, and aberrometric parameters improved significantly after Keraring AS implantation.
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Affiliation(s)
- E Coskunseven
- Département de chirurgie réfractive, hôpital Dunyagoz Etiler, Istanbul, Turkey; Faculté des sciences de la santé, université Rumeli d'Istanbul, Istanbul, Turkey
| | - B Kayhan
- Département de chirurgie réfractive, hôpital Dunyagoz Etiler, Istanbul, Turkey; Département d'ophtalmologie, Sultan II, hôpital de formation et de recherche Abdulhamid Han, université des sciences de la santé, Istanbul, Turkey.
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Kim NE, Ahn HM, Jun I, Seo KY, Kim TI, Park SY. Thin but Nonkeratoconic Cornea: A Case Report. KOREAN JOURNAL OF OPHTHALMOLOGY 2022; 36:565-567. [PMID: 36220640 DOI: 10.3341/kjo.2022.0053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 08/19/2022] [Indexed: 12/14/2022] Open
Affiliation(s)
- Na Eun Kim
- Institute of Vision Research, Department of Ophthalmology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | | | - Ikhyun Jun
- Institute of Vision Research, Department of Ophthalmology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Kyoung Yul Seo
- Institute of Vision Research, Department of Ophthalmology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
| | - Tae-Im Kim
- Institute of Vision Research, Department of Ophthalmology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea
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Eskina E, Klokova O, Damashauskas R, Davtyan K, Pajic B, Movsesian M. Visual Outcomes of Small-Incision Lenticule Extraction (SMILE) in Thin Corneas. J Clin Med 2022; 11:jcm11144162. [PMID: 35887926 PMCID: PMC9324047 DOI: 10.3390/jcm11144162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 07/09/2022] [Accepted: 07/13/2022] [Indexed: 02/04/2023] Open
Abstract
We aimed to find out whether thin (≤500 μm) or normal (>500 μm, control) corneal thickness would impact efficacy and safety outcomes of small-incision lenticule extraction (SMILE). We retrospectively analyzed medical records of adult patients who had undergone SMILE. A total of 57 eyes were included in the “thin corneas” group and 180 eyes in the “control” group. At one month after surgery, rates of patients with uncorrected distance visual activity (UDVA) ≥ 0.8 were significantly higher in patients from the control group compared to the “thin corneas” group (87 vs. 71%, respectively p < 0.01), though rates were comparable at 3 months (87 vs. 76%, respectively, p > 0.05). SMILE had comparable safety in patients with thin and normal corneas. Procedure result predictability was comparable between groups. Regression analysis demonstrated that cap thickness impacted posterior corneal biomechanics, and the volume of removed tissue had a higher influence in patients with thin corneas. Moreover, an increase in cap thickness was associated with better final BCVA. Further study is needed for the evaluation of the impact of thin corneas on SMILE outcomes and planning. Our study also indicates that patients with thin corneas might require a different approach to nomogram calculation.
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Affiliation(s)
- Erika Eskina
- Ophthalmological Clinic “Sphere”, 117628 Moscow, Russia;
- Academy of Postgraduate Education of Federal State Budgetary Foundation Federal Research-Clinical Center Federal Medical-Biological Agency of Russia, 125310 Moscow, Russia
- Correspondence:
| | - Olga Klokova
- Krasnodar Branch of The Sviatoslav Fyodorov Eye Microsurgery Federal State Institution, 350012 Krasnodar, Russia; (O.K.); (R.D.)
| | - Roman Damashauskas
- Krasnodar Branch of The Sviatoslav Fyodorov Eye Microsurgery Federal State Institution, 350012 Krasnodar, Russia; (O.K.); (R.D.)
| | | | - Bojan Pajic
- Swiss Eye Research Foundation, Titlisstrasse 44, 5734 Reinach, Switzerland;
- Eye Clinic ORASIS, Titlisstrasse 44, 5734 Reinach, Switzerland
- Division of Ophthalmology, Department of Clinical Neurosciences, Geneva University Hospitals, 1205 Geneva, Switzerland
- Faculty of Medicine, University of Geneva, 1205 Geneva, Switzerland
- Faculty of Sciences, Department of Physics, University of Novi Sad, Trg Dositeja Obradovica 4, 21102 Novi Sad, Serbia
- Faculty of Medicine of the Military Medical Academy, University of Defense, 11000 Belgrade, Serbia
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13
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Comparison of Total Corneal Astigmatism between IOLMaster and Pentacam. BIOMED RESEARCH INTERNATIONAL 2022; 2022:9236006. [PMID: 35845936 PMCID: PMC9286877 DOI: 10.1155/2022/9236006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 05/27/2022] [Accepted: 06/17/2022] [Indexed: 11/18/2022]
Abstract
Purpose. To compare the total corneal astigmatism (TCA) measured by IOLMaster 700 and Pentacam and to investigate the consistency of corneal keratometry (CK) measured by IOLMaster and Pentacam. Methods. Cataract patients were retrospectively enrolled in March and April, 2021. Retrospective analysis was performed on those patients with binocular and monocular CK measured by IOLMaster and Pentacam. Results. A total of 102 patients (204 eyes) were included, 64 of whom were female (62.75%). The flat (K1) and steep (K2) CK of anterior corneal surface (ACS) and flat (TK1) and steep (TK2) of total cornea measured with IOLMaster 700 were
,
,
, and
, respectively. Those measured with Pentacam were
,
,
, and
, respectively. The astigmatism of ACS and TCA were
and
(
) in the IOLMaster group and
and
in the Pentacam group, respectively (
). TCA measurement results of IOLMaster and Pentacam were consistent (
,
), and there was no significant difference (
). Conclusions. Total corneal astigmatism measured by IOLMaster was consistent with that measured by Pentacam. The difference between the astigmatism of anterior corneal surface and total cornea was detected in the measurement of IOLMaster and Pentacam, respectively.
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Henriquez MA, Hadid M, Moctezuma C, Izquierdo L, Binder PS. The false positive rates for detecting keratoconus and potential ectatic corneal conditions when evaluating astigmatic eyes with Scheimpflug Technology. Eur J Ophthalmol 2022; 32:2532-2546. [PMID: 35313744 DOI: 10.1177/11206721221081467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE To quantify the false positive rates for keratoconus (KC) and potential ectatic corneal conditions in highly astigmatism eyes when using published parameters/indices obtained from the Pentacam and Galilei units. SETTING Oftalmosalud Instituto de Ojos, Lima, Peru. DESIGN Prospective cohort study. METHODS 67 consecutive eyes with corneal astigmatism > 1.5 D, with a minimum follow ups of 36 months after an uneventful LASIK procedure were included. Indices for KC and other potential ectatic corneal conditions (subclinical KC, forme fruste KC, suspect KC) were obtained using the Pentacam and Galilei Scheimpflug cameras. MAIN OUTCOME MEASURES The false positive rates for KC and potential ectatic corneal conditions were measured. Cut off values provided by previous studies and company-based parameters were used to assess the rate of false positivity. RESULTS The range of false positive rates for a KC diagnosis depending on the lowest and highest cutoff values were: index of height decentration (61% - 1%), index of surface variance (76% - 0%), Posterior elevation (55% - 0%), maximum Ambrosio Relational thickness (100% - 13%), Belin Ambrosio enhanced ectasia display total deviation value (100% - 4%), Average pachymetric progression index (69% - 3%), Pachymetry at the thinnest point (58% - 1%), CSI Center Surround Index (100%), Differential sector index (51%). CONCLUSION The false positive rates for KC and ectatic corneal conditions vary dramatically depending on the cut-off values used. Some indexes used for diagnosis of potential ectatic corneal conditions are inaccurate in normal, highly astigmatic eyes.
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Affiliation(s)
- Maria A Henriquez
- Research Department, 568280Oftalmosalud Institute of Eyes, Av. Javier Prado Este 1142, San Isidro, Lima 27, Perú
| | - Marta Hadid
- Research Department, 568280Oftalmosalud Institute of Eyes, Av. Javier Prado Este 1142, San Isidro, Lima 27, Perú
| | - Cristobal Moctezuma
- Research Department, 568280Oftalmosalud Institute of Eyes, Av. Javier Prado Este 1142, San Isidro, Lima 27, Perú
| | - Luis Izquierdo
- Research Department, 568280Oftalmosalud Institute of Eyes, Av. Javier Prado Este 1142, San Isidro, Lima 27, Perú
| | - Perry S Binder
- 481087Gavin Herbert Eye Institute, University of California, Irvine, California, USA
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15
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Kandel S, Chaudhary M, Mishra SK, Joshi ND, Subedi M, Puri PR, Gyawali P, Bist J, Kandel H. Evaluation of corneal topography, pachymetry and higher order aberrations for detecting subclinical keratoconus. Ophthalmic Physiol Opt 2022; 42:594-608. [PMID: 35147226 DOI: 10.1111/opo.12956] [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: 06/03/2021] [Revised: 01/10/2022] [Accepted: 01/10/2022] [Indexed: 10/19/2022]
Abstract
PURPOSE To compare corneal topography, pachymetry and higher order aberrations in keratoconic and normal eyes; to investigate their association in keratoconic eyes; and to determine their diagnostic ability for detecting subclinical keratoconus in a Nepalese population. METHODS Ninety-six eyes of 48 keratoconus patients and 50 normal eyes of 50 control subjects were included in this study. The eyes of keratoconus patients were classified into four different study groups: subclinical, stage 1, stage 2 and advanced stage keratoconus. In each eye, corneal topography, pachymetry and corneal aberrometry indices were measured using a Sirius corneal tomographer. The study parameters of keratoconic eyes were compared with normal eyes, and the possible association of corneal aberrometry with topography and pachymetry indices was investigated. The area under curve (AUC) of receiver operating characteristic (ROC) curves along with optimal cutoff values with best sensitivity and specificity were also determined for each index to detect subclinical keratoconus. RESULTS All the indices except average keratometry measurements (Kavg and mmavg ) and spherical aberration (SA) were found to be significantly different in subclinical keratoconus compared to the control group (p < 0.05). In keratoconic eyes, all corneal aberrations were significantly correlated with the topography and pachymetry indices (range of ρ: -0.25 to 0.96; all p < 0.05) except for trefoil and minimum corneal thickness (Thkmin ). All the indices except Kavg , mmavg and SA showed excellent diagnostic ability (AUC > 0.90) in detecting subclinical keratoconus. The cutoff values proposed for the asymmetry index of the corneal back surface (SIb ), Strehl ratio of point spread function (PSF), coma and Baiocchi-Calossi-Versaci index of corneal back surface (BCVb ) each showed excellent sensitivity (100%) and specificity (≥97%). CONCLUSIONS Corneal higher order aberrations were found to be significantly elevated in subclinical keratoconus compared to healthy controls. SIb , PSF, coma and BCVb were identified as the most powerful Sirius indices for the detection of subclinical keratoconus.
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Affiliation(s)
- Sandeep Kandel
- Tilganga Institute of Ophthalmology, Gaushala, Kathmandu, Nepal
| | - Meenu Chaudhary
- B.P. Koirala Lions Center for Ophthalmic Studies, Institute of Medicine, Tribhuvan University, Kathmandu, Nepal
| | - Sanjeeb K Mishra
- B.P. Koirala Lions Center for Ophthalmic Studies, Institute of Medicine, Tribhuvan University, Kathmandu, Nepal
| | - Niraj D Joshi
- B.P. Koirala Lions Center for Ophthalmic Studies, Institute of Medicine, Tribhuvan University, Kathmandu, Nepal
| | - Manish Subedi
- B.P. Koirala Lions Center for Ophthalmic Studies, Institute of Medicine, Tribhuvan University, Kathmandu, Nepal
| | - Prajjol R Puri
- B.P. Koirala Lions Center for Ophthalmic Studies, Institute of Medicine, Tribhuvan University, Kathmandu, Nepal
| | - Parash Gyawali
- B.P. Koirala Lions Center for Ophthalmic Studies, Institute of Medicine, Tribhuvan University, Kathmandu, Nepal
| | - Jeewanand Bist
- Tilganga Institute of Ophthalmology, Gaushala, Kathmandu, Nepal
| | - Himal Kandel
- Specialty of Clinical Ophthalmology and Eye Health, Sydney Medical School, Faculty of Medicine and Health, Save Sight Institute, The University of Sydney, Sydney, New South Wales, Australia
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The effect of limbal autograft location at primary pterygium excision on anterior and posterior corneal astigmatism: a comparative prospective study. Int Ophthalmol 2022; 42:2235-2243. [DOI: 10.1007/s10792-022-02223-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 01/09/2022] [Indexed: 10/19/2022]
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Interocular Symmetry Analysis of Corneal Elevation Using the Fellow Eye as the Reference Surface and Machine Learning. Healthcare (Basel) 2021; 9:healthcare9121738. [PMID: 34946464 PMCID: PMC8702115 DOI: 10.3390/healthcare9121738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 12/12/2021] [Accepted: 12/13/2021] [Indexed: 11/16/2022] Open
Abstract
Unilateral corneal indices and topography maps are routinely used in practice, however, although there is consensus that fellow-eye asymmetry can be clinically significant, symmetry studies are limited to local curvature and single-point thickness or elevation measures. To improve our current practices, there is a need to devise algorithms for generating symmetry colormaps, study and categorize their patterns, and develop reference ranges for new global discriminative indices for identifying abnormal corneas. In this work, we test the feasibility of using the fellow eye as the reference surface for studying elevation symmetry throughout the entire corneal surface using 9230 raw Pentacam files from a population-based cohort of 4613 middle-aged adults. The 140 × 140 matrix of anterior elevation data in these files were handled with Python to subtract matrices, create color-coded maps, and engineer features for machine learning. The most common pattern was a monochrome circle (“flat”) denoting excellent mirror symmetry. Other discernible patterns were named “tilt”, “cone”, and “four-leaf”. Clustering was done with different combinations of features and various algorithms using Waikato Environment for Knowledge Analysis (WEKA). Our proposed approach can identify cases that may appear normal in each eye individually but need further testing. This work will be enhanced by including data of posterior elevation, thickness, and common diagnostic indices.
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Zaabaar E, Kyei S, Parkson Brew MAA, Boadi-Kusi SB, Assiamah F, Asiedu K. The utility of measures of anterior segment parameters of a Pentacam Scheimpflug tomographer in discriminating high myopic astigmatism from keratoconus. PLoS One 2021; 16:e0260648. [PMID: 34855828 PMCID: PMC8638937 DOI: 10.1371/journal.pone.0260648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 11/13/2021] [Indexed: 11/20/2022] Open
Abstract
The study aimed to evaluate and compare anterior segment parameters between keratoconic eyes and eyes with high myopic astigmatism using Pentacam Scheimpflug tomography. This was a retrospective cross-sectional study that included sixty keratoconic eyes (thirty-two persons) and seventy-three eyes (forty-six persons) with high myopic astigmatism with mean ages 24.72 ± 11.65years and 26.60 ± 10.69years, respectively. Twenty-three parameters from the topographic map and fifteen parameters from the Belin-Ambrosió enhanced ectasia display map of the printouts of a Scheimpflug principle-based Pentacam tomographer were evaluated for their diagnostic accuracy using Receiver Operating Characteristic (ROC) curve. All parameters except cornea volume, anterior chamber volume, and anterior chamber angle indicated a significant difference between high myopic astigmatism and keratoconic eyes. The area under the receiver operating characteristic (AUROC) of eighteen Pentacam parameters was excellent (0.9–1.0) in discriminating keratoconus from high myopic astigmatism, out of which four {anterior minimum sagittal curvature (ant. Rmin), posterior minimum sagittal curvature (post. Rmin), maximum Ambrosió relational thickness (ART max) and total deviation value (D)} indicated excellent (>90%) sensitivity and specificity in addition to the excellent AUROC values. Topographic and Belin-Ambrosió enhanced ectasia display (BAD) maps of a Scheimpflug principle-based Pentacam tomographer are useful in enhancing the diagnosis of keratoconus and may also provide valuable information in effectively screening for keratoconus cases among refractive surgery candidates with high myopic astigmatism.
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Affiliation(s)
- Ebenezer Zaabaar
- Department of Optometry and Vision Science, School of Allied Health Sciences, College of Health and Allied Sciences, University of Cape Coast, Cape Coast, Ghana
| | - Samuel Kyei
- Department of Optometry and Vision Science, School of Allied Health Sciences, College of Health and Allied Sciences, University of Cape Coast, Cape Coast, Ghana
- * E-mail:
| | - Maame Ama Amamoah Parkson Brew
- Department of Imaging Technology and Sonography, School of Allied Health Sciences, College of Health and Allied Sciences, University of Cape Coast, Cape Coast, Ghana
| | - Samuel Bert Boadi-Kusi
- Department of Optometry and Vision Science, School of Allied Health Sciences, College of Health and Allied Sciences, University of Cape Coast, Cape Coast, Ghana
| | - Frank Assiamah
- Eye Department, Korle-Bu Teaching Hospital, Accra, Ghana
| | - Kofi Asiedu
- Eye Clinic Cosmopolitan Medical Center, Dworwulu, Accra, Ghana
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Shah Z, Shilpy N, Purohit D, Singh S. Assessment and Correlation of Corneal Endothelial Cell Changes in Different Stages of Keratoconus in Non-contact Lens Wearers. Optom Vis Sci 2021; 98:1295-1298. [PMID: 34510150 DOI: 10.1097/opx.0000000000001805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
SIGNIFICANCE The endothelial changes in keratoconus are of interest because these can affect the surgical plan in management. Previously, many studies have evaluated the endothelium in eyes with keratoconus, but there is no common consensus on change in endothelial cell density (ECD) with studies showing variable results. PURPOSE This study aimed to compare and correlate endothelial cell parameters in different stages of keratoconus using specular microscope. METHODS This cross-sectional, cohort, comparative study included 162 eyes of 96 patients with keratoconus in one or both eyes. Corneal endothelial cell parameters were assessed with SP-1P specular microscope (Topcon Co., Tokyo, Japan). Corneal topography and thickness data were obtained from Sirius tomographer (Costruzione Strumenti Oftalmici, Florence, Italy). Eyes were divided into keratoconus stage 0 to 4 according to ABCD classification. Comparison and correlation of endothelial cell parameters in different stages were done. RESULTS There were 21.6% eyes (35) in stage 0, 29.6% eyes (48) in stage 1, 29.0% eyes (47) in stage 2, and 19.8% eyes (32) in stage 3 of keratoconus. Measurement was not possible in stage 4 keratoconus. Among the stages 0, 1, 2, and 3, the ECD was 3024, 3051, 3025, and 3043 cells/mm2; coefficient of variation was 27.2, 27.6, 26.8, and 27.4; and frequency of hexagon cells was 61.5, 63.7, 63.3, and 62.3, respectively (P > .05). The number of analyzed cells was 232, 209, 185, and 169 in stages 0, 1, 2, and 3, respectively (P < .001). No significant difference was found in minimum, maximum, and average cell area between the stages (P > .05). A weak Spearman rank correlation of ECD, coefficient of variation, and frequency of hexagon cells was found between eyes with keratoconus stages 0 and 1 and stages 2 and 3 (r = -0.05, P = .65; r = -0.11, P = .37; r = 0.05, P = .67, respectively). No significant correlation was found in the number of cells analyzed and minimum, maximum, and average cell area between the stages (P > .05). CONCLUSIONS Endothelial cell parameters do not show any significant changes and correlation up to stage 3 of keratoconus in non-contact lens wearers.
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Affiliation(s)
| | - Neha Shilpy
- Regional Institute of Ophthalmology, Rajendra Institute of Medical Sciences, Ranchi, Jharkhand, India
| | - Dipali Purohit
- Department of Refractive Surgery, Shree C. H. Nagri Eye Hospital, Ahmedabad, Gujarat, India
| | - Shwetambari Singh
- Department of Refractive Surgery, Shree C. H. Nagri Eye Hospital, Ahmedabad, Gujarat, India
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Abstract
ABSTRACT The advent of refractive surgery and corneal cross-linking for ectatic disease has further highlighted the need to recognize early or subclinical ectatic disease. Historical systems depend on anterior corneal changes that occur late in the disease course and are commonly associated with visual loss. Tomographic imaging allows for the acquisition of posterior corneal surface data and corneal thickness distribution. This led to the development of modalities to diagnose early or subclinical keratoconus and to screen patients for refractive surgery.This article reviews the modern methods for assessing changes in posterior corneal surface and pachymetric distribution, now accepted by the major cornea societies to be the hallmarks of ectatic disease. Screening tools utilized by the commonly used tomographic imaging devices are discussed, and the difference between screening for ectasia and diagnosing keratoconus is highlighted. The Belin ABCD staging and classification system and the ABCD Progression Display are reviewed as a new grading and monitoring system that can be used for earlier intervention and prevention of visual loss in keratoconus.
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