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Coutinho CP, Schiano-Lomoriello D, Mazzotta C, Ferrise M, Hoffer KJ, Ribeiro FJ, Dias JM, Savini G. Differences Between Simulated Keratometry and Total Corneal Power in Eyes With Keratoconus and a Formula to Improve IOL Power Calculation Results. J Refract Surg 2024; 40:e253-e259. [PMID: 38593262 DOI: 10.3928/1081597x-20240311-06] [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 simulated keratometry (SimK) and total corneal power (TCP) in keratoconic eyes, to determine whether the differences are systematic and predictable and to evaluate an adjusted TCP-based formula for intraocular lens (IOL) power calculation. METHODS In a consecutive series of keratoconic eyes, measurements of SimK, TCP, posterior keratometry, and anterior and posterior corneal asphericities (Q-values) were retrospectively collected. The difference between SimK and TCP was linearly correlated to the biometric parameters. In a separate sample of keratoconic eyes that had undergone cataract surgery, IOL power was calculated with the Barrett Universal II, Hoffer QST, Holladay 1, Kane, and SRK/T formulas using the SimK and an adjusted TCP power. The respective prediction errors were calculated. RESULTS A total of 382 keratoconic eyes (271 patients) were enrolled. An increasing overestimation of SimK by TCP was detected from stage I to III, with a significant correlation between the SimK and TCP difference and SimK in the whole sample (P < .0001, r2 = 0.1322). Approximately 7% of cases presented an underestimation of SimK by TCP. IOL power calculation with the adjusted TCP improved outcomes, achieving a maximum of 80% of eyes with a prediction error within ±0.50 diopters with the Hoffer QST, Holladay 1, and Kane formulas. CONCLUSIONS Overall, SimK overestimated TCP. Such a difference could not be predicted by any variable. The proposed TCP-adjustment formula (TCPadj = TCP + 0.56 diopters) in keratoconic eyes for IOL power calculation might be valuable for improving refractive outcomes. [J Refract Surg. 2024;40(4):e253-e259.].
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Chetty E. Multivariate analysis of refractive state in eyes with keratoconus. BMJ Open Ophthalmol 2023; 8:e001344. [PMID: 37580104 PMCID: PMC10432643 DOI: 10.1136/bmjophth-2023-001344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 08/01/2023] [Indexed: 08/16/2023] Open
Abstract
OBJECTIVE To demonstrate a multivariate method of analysis of the short-term variation of refractive state in keratoconus (KC) patients. METHODS AND ANALYSIS In this observational study, 19 eyes with KC and 19 healthy control eyes were measured. The study included both male and female participants and the mean age was 23.6 years (range 18-34 years) and 23.2 years (range 22-26 years) for KC and control participants, respectively. Forty consecutive autorefractor measurements were taken for each participant and the short-term variation thereof was analysed using multivariate methods of analysis. RESULTS AND CONCLUSION Short-term variation of refractive state is greater in eyes with KC than in healthy control eyes and variation increases with severity of disease. A novel finding was that there was much more ortho-astigmatic and oblique-astigmatic variation seen in KC eyes than in control eyes which had predominately stigmatic variation. Refractive state is described by three components, namely, sphere, cylinder and axis. Although it is multivariate in nature, it is often analysed using univariate statistical methods. In diseases such as KC, where early diagnosis is crucial for a good prognosis, it is necessary that researchers endeavour to investigate the disease from different perspectives to fully understand the nature of the disease. This paper comprehensively demonstrates the multivariate statistical methods of analysis of refractive data. The implementation of this analysis provides insight into the short-term variation of refractive data in healthy and keratoconic eyes, and these findings have not been demonstrated before using univariate statistics.
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Affiliation(s)
- Elizabeth Chetty
- Department of Optometry, University of Johannesburg, Auckland Park, South Africa
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Cha DS, Moshirfar M, Herron MS, Santos JM, Hoopes PC. Prediction of Posterior-to-Anterior Corneal Curvature Radii Ratio in Myopic Patients after LASIK, SMILE, and PRK Using Multivariate Regression Analysis. J Clin Med 2023; 12:4536. [PMID: 37445571 DOI: 10.3390/jcm12134536] [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: 05/28/2023] [Revised: 06/28/2023] [Accepted: 07/05/2023] [Indexed: 07/15/2023] Open
Abstract
The ratio of posterior-to-anterior curvature radii of the cornea (P/A ratio) is an important element in determining corneal refractive power. P/A ratio has been well studied in patients prior to undergoing refractive surgery, but its postoperative value remains less so. We aimed to examine the value of preoperative characteristics of refractive surgery patients in predicting the 1-year postoperative P/A ratio in LASIK, PRK, and SMILE using both linear and multivariate regression analyses. This was a retrospective study that included patients with manifest refraction spherical equivalents (MRSE) from -7.71D to -0.25D. In total, 164 eyes underwent LASIK, 183 underwent PRK, and 46 underwent SMILE. All patients had preoperative and 1-year postoperative front sagittal and back sagittal keratometry measurements at 4, 5, and 6 mm around the corneal vertex. Postoperative P/A after LASIK, PRK, and SMILE was found to be significantly correlated with MRSE and preoperative P/A. Stepwise variable selection in multivariate regression revealed that spherical equivalent was the most significant predictor of postoperative P/A. When coupled with other preoperative characteristics, including P/A, age, asphericity, and keratometry, the multivariate regressions were able to produce models with high predictive value in LASIK (adjusted R2: 0.957), PRK (adjusted R2: 0.934), and SMILE (adjusted R2: 0.894).
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Affiliation(s)
- David S Cha
- School of Medicine, Saint Louis University, Saint Louis, MO 63104, USA
| | - Majid Moshirfar
- Hoopes Vision Research Center, Hoopes Vision, Draper, UT 84020, USA
- John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, UT 84132, USA
- Utah Lions Eye Bank, Murray, UT 84107, USA
| | - Michael S Herron
- University of Nevada, Reno School of Medicine, Reno, NV 89557, USA
| | - Jordan M Santos
- University of Arizona College of Medicine Phoenix, Phoenix, AZ 85004, USA
| | - Phillip C Hoopes
- Hoopes Vision Research Center, Hoopes Vision, Draper, UT 84020, USA
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Polido J, Araújo MEXDS, Wakamatsu TH, Alexander JG, Cabral T, Ambrósio R, Freitas D. Long-term Safety and Efficacy of Corneal Collagen Crosslinking in a Pediatric Group With Progressive Keratoconus: A 7-year Follow-up. Am J Ophthalmol 2023; 250:59-69. [PMID: 36682518 DOI: 10.1016/j.ajo.2023.01.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 01/09/2023] [Accepted: 01/11/2023] [Indexed: 01/22/2023]
Abstract
PURPOSE To assess effectiveness and safety of corneal crosslinking (CXL) to reduce keratoconus (KC) progression and improve visual acuity among children with progressive KC and to analyze the use of 20% dextran-based (Dextran) and 1% hydroxypropyl methylcellulose-based (HPMC) riboflavin. DESIGN Prospective, clinical cohort study METHODS: Standard CXL (SCXL) was performed in 74 eyes (58 patients, 45 males, mean age 13.0 ± 2.1 years): 53 eyes with HPMC and 21 with Dextran. Examinations were performed at baseline, 3 and 6 months, and 1, 2, 3, 4, 5, and 7 years of follow-up, including uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), a complete ophthalmologic examination, anterior segment ocular coherence tomography, Scheimpflug corneal tomography, and specular microscopy. RESULTS UDVA and CDVA improved at all periods with statistically significant differences in CDVA at 1, 2, and 3 years. Compared with baseline, maximum K (Max K) reduced throughout the 7-year follow-up. Mean thinnest pachymetry (Th Pachy) decreased significantly at 3 months and remained low; in the Dextran group, the Th Pachy mean value returned to baseline 6 months postoperatively. After CXL, 1.5 diopter progression in max K was 1.4% to 14.6% of eyes; worsening was found at 4 to 7 years postoperatively. CONCLUSION SCXL reduced KC progression in children up to 7 years of follow-up and revealed improvement and stability of UDVA and CDVA in 82% of eyes. For visual acuity and KC stability, no statistically significant difference was observed between Dextran-HPMC. The HPMC group showed persistent cornea thinning, raising concerns about its use in SCXL.
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Affiliation(s)
- Júlia Polido
- From the Department of Ophthalmology (J.P., M.E.X.A., T.H.K., J.G.A., T.C., R.A., D.F.), Federal University of São Paulo
| | - Maria Emília Xavier Dos Santos Araújo
- From the Department of Ophthalmology (J.P., M.E.X.A., T.H.K., J.G.A., T.C., R.A., D.F.), Federal University of São Paulo; Department of Ophthalmology (M.E.X.A), HSPE/IAMSPE, São Paulo
| | - Tais H Wakamatsu
- From the Department of Ophthalmology (J.P., M.E.X.A., T.H.K., J.G.A., T.C., R.A., D.F.), Federal University of São Paulo
| | - João G Alexander
- From the Department of Ophthalmology (J.P., M.E.X.A., T.H.K., J.G.A., T.C., R.A., D.F.), Federal University of São Paulo
| | - Thiago Cabral
- From the Department of Ophthalmology (J.P., M.E.X.A., T.H.K., J.G.A., T.C., R.A., D.F.), Federal University of São Paulo; Department of Ophthalmology EBSERH (T.C.), HUCAM/CCS-UFES, Federal University of Espírito Santo, Vitória.
| | - Renato Ambrósio
- From the Department of Ophthalmology (J.P., M.E.X.A., T.H.K., J.G.A., T.C., R.A., D.F.), Federal University of São Paulo; and the Department of Ophthalmology (R.A.), Federal University of the State of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Denise Freitas
- From the Department of Ophthalmology (J.P., M.E.X.A., T.H.K., J.G.A., T.C., R.A., D.F.), Federal University of São Paulo
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Gonzalez-Salinas R, Franco JJ, Reyes-Luis JL, Sánchez-Huerta V, de Wit-Carter G, Hernández-Quintela E, Pineda R. Cataract surgery in patients with underlying keratoconus: focused review. J Cataract Refract Surg 2023; 49:97-102. [PMID: 36194107 DOI: 10.1097/j.jcrs.0000000000001069] [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: 08/26/2022] [Accepted: 09/24/2022] [Indexed: 11/07/2022]
Abstract
An underlying diagnosis of keratoconus (KC) can complicate cataract surgery. In this study, the results of a focused review of the literature pertaining to cataract surgery in patients with KC are detailed. Topics essential for the appropriate management of this patient population are discussed. First, the individual and shared epidemiology and pathophysiology of cataract and KC are reviewed. Then, the theory and approach to intraocular lens power calculation are discussed, highlighting particularities and pitfalls of this exercise when performed in patients with KC. Finally, several special-although not uncommon-management scenarios and questions are addressed, such as surgical planning in cases where corneal stabilization or tissue replacement interventions are also necessitated.
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Affiliation(s)
- Roberto Gonzalez-Salinas
- From the Anterior Segment Surgery Department, Asociación para Evitar la Ceguera I.A.P., Mexico City, Mexico (Gonzalez-Salinas); Harvard Medical School, Boston, Massachusetts (Franco, Pineda); Cornea and Refractive Surgery Service, Massachusetts Eye and Ear, Boston, Massachusetts (Reyes-Luis, Pineda); Cornea Department, Asociación para Evitar la Ceguera I.A.P., Mexico City, Mexico (Sánchez-Huerta, de Wit-Carter); Division of Comprehensive Ophthalmology, Wilmer Eye Institute, Johns Hopkins Medicine, Baltimore, Maryland (Hernández-Quintela)
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Correlation between Placido's Disk and Rotating Scheimpflug Keratometric Findings in Children with Keratoconus before and after Corneal Cross-Linking. J Cataract Refract Surg 2022; 48:1183-1189. [PMID: 35333826 DOI: 10.1097/j.jcrs.0000000000000944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2021] [Accepted: 03/19/2022] [Indexed: 11/26/2022]
Abstract
PURPOSE Evaluate correlation between Placido's disk and rotating Scheimpflug keratometric findings in children with progressive keratoconus (KC) before and after corneal cross-linking (CXL) and investigate whether these limits of agreement varied according to disease severity. SETTING Department of Ophthalmology of São Paulo Hospital, São Paulo, Brazil. DESIGN Prospective nonrandomized open study. METHODS Data obtained using rotating Scheimpflug-based tomography and Placido-based topography devices were collected from preoperative and last follow-up postoperative children with KC operated on using standard CXL protocol. Correlation and agreement analyses were performed between the two devices before and after CXL to obtain keratometric findings. RESULTS Forty-four eyes from 44 patients 8 to 16 years of age were analyzed at all time points. All parameters were found to be strongly correlated before (r = 0.84-0.99, p < 0.001) and after (r = 0.93-0.99, p < 0.001) CXL. Mean Scheimpflug measurements of flat K, steep K, Kmax, mean K, and corneal astigmatism were higher than Placido measurements in preoperative period. This mean difference decreased in postoperative, but, with exception of Kmax and corneal astigmatism, Scheimpflug measurements remained higher. Mean parameter measurements from both devices decreased after CXL. 95% limits of agreement between instruments were wide for all parameters, and decreased in postoperative and in mild KC. CONCLUSION Keratometry measurements obtained using rotating Scheimpflug and Placido disk technology were found to be closely correlated but not interchangeable before and after CXL in pediatric patients. Agreement between devices was better after CXL and in mild KC than in advanced KC.
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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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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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Abstract
Pupillometry - the study of temporal changes in pupil diameter as a function of external light stimuli or cognitive processing - requires the accurate and gaze-angle independent measurement of pupil dilation. Expected response amplitudes often are only a few percent relative to a pre-stimulus baseline, thus demanding for sub-millimeter accuracy. Video-based approaches to pupil-size measurement aim at inferring pupil dilation from eye images alone. Eyeball rotation in relation to the recording camera as well as optical effects due to refraction at corneal interfaces can, however, induce so-called pupil foreshortening errors (PFE), i.e. systematic gaze-angle dependent changes of apparent pupil size that are on a par with typical response amplitudes. While PFE and options for its correction have been discussed for remote eye trackers, for head-mounted eye trackers such an assessment is still lacking. In this work, we therefore gauge the extent of PFE in three measurement techniques, all based on eye images recorded with a single near-eye camera. We present both real world experimental data as well as results obtained on synthetically generated eye images. We discuss PFE effects at three different levels of data aggregation: the sample, subject, and population level. In particular, we show that a recently proposed refraction-aware approach employing a mathematical 3D eye model is successful in providing pupil-size measurements which are gaze-angle independent at the population level.
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Camps VJ, Riad RRF, Caravaca-Arens E, Labib FE, Mateo V, Caballero MT, Piñero DP. Comparison of Four Intraocular Power Calculation Formulas in Keratoconus Eyes. Open Ophthalmol J 2021. [DOI: 10.2174/1874364102115010096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Introduction:
This study aimed to evaluate the differences in Intraocular Lens (IOL) power in keratoconus (KC) eyes between calculations obtained clinically with the most commonly used formulas in healthy eyes (SRK T, Holladay 1, Hoffer Q and Haigis) as well as to define predictive factors for such differences.
Methods:
This retrospective study comprised 43 keratoconus eyes of 22 patients with no previous ocular surgery. IOL powers were calculated with SRK T, Holladay 1, Hoffer Q, and Haigis formulas, considering the Effective Lens Position (ELP) of each formula and the desired refraction of 0 D (Rdes=0 D).
Results:
All differences between formulas were statistically significant and clinically relevant. Haigis formula always provided higher values compared to the rest of the formulas, with the highest differences observed when comparing Haigis with Hoffer (0.84 D) and Hoffer Q (1.17 D) formulas. The lowest difference was obtained for the comparison between SRK-T and Holladay 1 formulas (0.22 D). Differences of the Haigis formula compared to the rest were higher as the magnitude of the IOL power calculated decreased, becoming the patient more myopic. Increased differences between Haigis and Hoffer formulas were observed in eyes with deep anterior chambers, steeper anterior and posterior corneal surfaces, and high axial lengths.
Conclusion:
The most comparable results in IOL power in keratoconus are provided by the Holladay 1 and SRK T formulas, whereas the Haigis formula provides the most discrepant outcome. The consideration of the curvature of the second corneal surface in IOL power calculations in keratoconus may decrease the variability between calculation methods. However, other factors as anterior chamber depth or axial length are also relevant.
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Zhou D, Abass A, Lopes B, Eliasy A, Hayes S, Boote C, Meek KM, Movchan A, Movchan N, Elsheikh A. Fibril density reduction in keratoconic corneas. J R Soc Interface 2021; 18:20200900. [PMID: 33622146 DOI: 10.1098/rsif.2020.0900] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
This study aims to estimate the reduction in collagen fibril density within the central 6 mm radius of keratoconic corneas through the processing of microstructure and videokeratography data. Collagen fibril distribution maps and topography maps were obtained for seven keratoconic and six healthy corneas, and topographic features were assessed to detect and calculate the area of the cone in each keratoconic eye. The reduction in collagen fibril density within the cone area was estimated with reference to the same region in the characteristic collagen fibril maps of healthy corneas. Together with minimum thickness and mean central corneal refractive power, the cone area was correlated with the reduction in the cone collagen fibrils. For the corneas considered, the mean area of keratoconic cones was 3.30 ± 1.90 mm2. Compared with healthy corneas, fibril density in the cones of keratoconic corneas was lower by as much as 35%, and the mean reduction was 17 ± 10%. A linear approximation was developed to relate the magnitude of reduction to the refractive power, minimum corneal thickness and cone area (R2 = 0.95, p < 0.001). Outside the cone area, there was no significant difference between fibril arrangement in healthy and keratoconic corneas. The presented method can predict the mean fibril density in the keratoconic eye's cone area. The technique can be applied in microstructure-based finite-element models of the eye to regulate its stiffness level and the stiffness distribution within the areas affected by keratoconus.
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Affiliation(s)
- Dong Zhou
- Department of Mathematical Sciences, School of Physical Sciences, University of Liverpool, Liverpool, UK
| | - Ahmed Abass
- Department of Mechanical, Materials and Aerospace Engineering, School of Engineering, University of Liverpool, Liverpool, UK.,Department of Production Engineering and Mechanical Design, Faculty of Engineering, Port Said University, Egypt
| | - Bernardo Lopes
- Department of Civil Engineering and Industrial Design, School of Engineering, University of Liverpool, Liverpool, UK.,Department of Ophthalmology, Federal University of Sao Paulo, Brazil
| | - Ashkan Eliasy
- Department of Civil Engineering and Industrial Design, School of Engineering, University of Liverpool, Liverpool, UK
| | - Sally Hayes
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
| | - Craig Boote
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
| | - Keith M Meek
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
| | - Alexander Movchan
- Department of Mathematical Sciences, School of Physical Sciences, University of Liverpool, Liverpool, UK
| | - Natalia Movchan
- Department of Mathematical Sciences, School of Physical Sciences, University of Liverpool, Liverpool, UK
| | - Ahmed Elsheikh
- Department of Civil Engineering and Industrial Design, School of Engineering, University of Liverpool, Liverpool, UK.,Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing 100083, People's Republic of China.,NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
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Chetty E, Rubin A. A comparison of anterior and posterior central corneal powers in eyes with and without keratoconus. AFRICAN VISION AND EYE HEALTH 2020. [DOI: 10.4102/aveh.v79i1.607] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
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Kim J, Whang WJ, Kim HS. Analysis of total corneal astigmatism with a rotating Scheimpflug camera in keratoconus. BMC Ophthalmol 2020; 20:475. [PMID: 33272234 PMCID: PMC7713345 DOI: 10.1186/s12886-020-01747-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 11/25/2020] [Indexed: 12/01/2022] Open
Abstract
Background To analyze mean corneal powers and astigmatisms on anterior, posterior, and total cornea in patients with keratoconus as calculated according to various keratometric measurements using a Scheimpflug camera. Methods We examined the left eyes of 64 patients (41 males and 23 females; mean age 29.94 ± 6.63 years) with keratoconus. We measured simulated K (Sim-K), posterior K, true net power (TNP) and four types of total corneal refractive powers (TCRP). We then used the obtained values to analyze mean K, and corneal astigmatism. TCRP were measured at 2.0 ~ 5.0 mm. Results Mean corneal powers from Sim K, posterior K, and TNP were 49.12 ± 3.99, − 7.39 ± 0.79, and 47.78 ± 4.09 diopters, respectively. For TCRP centered on the pupil, mean K tended to decrease with measurement area (all p < 0.01). While, both mean K and astigmatism measured using TCRP centered on the apex decreased with measurement area (all p < 0.001). TCRP centered on the apex were greater than those centered on the pupil for mean K values calculated using TCRP (all p < 0.001). The proportion of WTR was greatest on the anterior and total cornea. As the measurement area moved to the periphery, the proportion of WTR increased. Conclusions Mean corneal powers and astigmatisms on total cornea with keratoconus change depending on calculation methods and measurement areas.
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Affiliation(s)
- Jinho Kim
- Department of Ophthalmology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, South Korea
| | - Woong-Joo Whang
- Department of Ophthalmology, Yeouido St. Mary's Hospital, College of Medicine, The Catholic University of Korea Korea, Seoul, South Korea.
| | - Hyun-Seung Kim
- Department of Ophthalmology, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, South Korea
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Miret JJ, Camps VJ, García C, Caballero MT, de Fez D, Piñero DP. New method to improve the quality of vision in cataractous keratoconus eyes. Sci Rep 2020; 10:20049. [PMID: 33208842 PMCID: PMC7674461 DOI: 10.1038/s41598-020-76977-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 10/27/2020] [Indexed: 01/19/2023] Open
Abstract
To analyze using optical simulations if the proper use of a segmented intraocular lens (IOL) can improve the visual outcomes compared to the implantation of a spherical monofocal IOL. The wavefront profile of the Mplus (Oculentis) and a monofocal IOLs with the phase transformation introduced by each IOL were calculated using a Hartmann-Shack wavefront sensor. In addition, the wavefront profile of schematic eye models of various keratoconus conditions was obtained and was propagated to the IOLs. The optical performance of such combination was obtained after combining ray tracing and Fourier optics. A pre-clinical validation was also evaluated incorporating clinical data from three different keratoconus eyes of three patients. The implantation of the Mplus IOL can compensate or reduce the overall coma of the eye with keratoconus improving the quality of vision compared with a spherical monofocal IOL due to lower displacements of the retinal image or tilting in keratoconus. All theoretical simulations were confirmed afterwards by mean of a preclinical validation. The use of a standard toric segmented IOL with a proper orientation and selection of the addition can improve the optical quality of the keratoconus eye compared to the use of a monofocal spherical IOL.
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Affiliation(s)
- Juan J Miret
- Grupo de Óptica y Percepción Visual (GOPV), Department of Optics, Pharmacology and Anatomy, University of Alicante, Crta San Vicente del Raspeig s/n, San Vicente del Raspeig, 03690, Alicante, Spain
| | - Vicente J Camps
- Grupo de Óptica y Percepción Visual (GOPV), Department of Optics, Pharmacology and Anatomy, University of Alicante, Crta San Vicente del Raspeig s/n, San Vicente del Raspeig, 03690, Alicante, Spain.
| | - Celia García
- Grupo de Óptica y Percepción Visual (GOPV), Department of Optics, Pharmacology and Anatomy, University of Alicante, Crta San Vicente del Raspeig s/n, San Vicente del Raspeig, 03690, Alicante, Spain
| | - María T Caballero
- Grupo de Óptica y Percepción Visual (GOPV), Department of Optics, Pharmacology and Anatomy, University of Alicante, Crta San Vicente del Raspeig s/n, San Vicente del Raspeig, 03690, Alicante, Spain
| | - Dolores de Fez
- Grupo de Óptica y Percepción Visual (GOPV), Department of Optics, Pharmacology and Anatomy, University of Alicante, Crta San Vicente del Raspeig s/n, San Vicente del Raspeig, 03690, Alicante, Spain
| | - David P Piñero
- Grupo de Óptica y Percepción Visual (GOPV), Department of Optics, Pharmacology and Anatomy, University of Alicante, Crta San Vicente del Raspeig s/n, San Vicente del Raspeig, 03690, Alicante, Spain.,Department of Ophthalmology, Vithas Medimar International Hospital, Alicante, Spain
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Zhang JX, Xu QY, Yang Y, Li N, Zhang Y, Deng LH, Zhu QX, Shen T. Kupffer cell inactivation ameliorates immune liver injury via TNF-α/TNFR1 signal pathway in trichloroethylene sensitized mice. Immunopharmacol Immunotoxicol 2020; 42:545-555. [PMID: 32811237 DOI: 10.1080/08923973.2020.1811306] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
METHODS 36 female BALB/c mice were selected and randomly divided the mice into four groups. We established a BALB/c mouse model of TCE sensitization and pretreatment with GdCl3 (40 mg/kg) by intraperitoneal injection during the during the 17th and 19th days. RESULTS We found F4/80, the marker of Kupffer cell, was increased in TCE positive group. GdCl3 treatment successfully blocked the activation of Kupffer cell. TNF-α was increased significantly in liver of TCE sensitized mice and decreased significantly when low-dose GdCl3 was used. We found TNF receptor 1 (TNFR1) was increased significantly and GdCl3 treatment resumed the expression of TNFR1 to normal level, as well as the F4/80, TNF-α and TNFR1 mRNA. We also found both caspase-8 and caspase-3 increased in TCE positive group and decreased in TCE + GdCl3 positive group. The number of apoptotic cells in TCE sensitized mice increased by TUNEL staining, and GdCl3 treatment alleviated this increase. Some cells showed edema and inflammatory cell aggregation in liver of TCE positive group, while in the TCE + GdCl3 positive group, the cytoplasm became loose and vacuole-like degeneration occurred. CONCLUSION Our study unveils cross-talk between Kupffer cell activation and TNFR1 which mediate apoptosis in liver of TCE sensitized mice.
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Affiliation(s)
- Jia-Xiang Zhang
- Department of Occupational Health and Environment Health, School of Public Health, Anhui Medical University, Hefei, Anhui, PR China.,Ministry of Education, Key Laboratory of Dermatology, Anhui Medical University, Hefei, Anhui, China
| | - Qiong-Ying Xu
- Department of Occupational Health and Environment Health, School of Public Health, Anhui Medical University, Hefei, Anhui, PR China
| | - Yi Yang
- Department of Occupational Health and Environment Health, School of Public Health, Anhui Medical University, Hefei, Anhui, PR China
| | - Na Li
- Department of Occupational Health and Environment Health, School of Public Health, Anhui Medical University, Hefei, Anhui, PR China
| | - Yan Zhang
- Department of Occupational Health and Environment Health, School of Public Health, Anhui Medical University, Hefei, Anhui, PR China
| | - Li-Hua Deng
- Shenzhen Prevention and Treatment Center for Occupational Disease, Shenzhen, Guangdong, PR China
| | - Qi-Xing Zhu
- Ministry of Education, Key Laboratory of Dermatology, Anhui Medical University, Hefei, Anhui, China.,Department of Dermatology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, PR China
| | - Tong Shen
- Department of Occupational Health and Environment Health, School of Public Health, Anhui Medical University, Hefei, Anhui, PR China.,Ministry of Education, Key Laboratory of Dermatology, Anhui Medical University, Hefei, Anhui, China
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16
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Velázquez JS, Cavas F, Piñero DP, Cañavate FJ, Alio del Barrio J, Alio JL. Morphogeometric analysis for characterization of keratoconus considering the spatial localization and projection of apex and minimum corneal thickness point. J Adv Res 2020; 24:261-271. [PMID: 32382446 PMCID: PMC7200195 DOI: 10.1016/j.jare.2020.03.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 03/26/2020] [Accepted: 03/26/2020] [Indexed: 02/07/2023] Open
Abstract
This work evaluates changes in new morphogeometric indices developed considering the position of anterior and posterior corneal apex and minimum corneal thickness (MCT) point in keratoconus. This prospective comparative study included 440 eyes of 440 patients (age, 7-99 years): control (124 eyes) and keratoconus (KC) groups (316 eyes). Tomographic information (Sirius®, Costruzione Strumenti Oftalmici, Italy) was treated with SolidWorks v2013, creating the following morphogeometric parameters: geometric axis-apex line angle (GA-AP), geometric axis-MCT line angle (GA-MCT, apex line-MCT line angle (AP-MCT), and distances between apex and MCT points on the anterior (anterior AP-MCTd) and posterior corneal surface (posterior AP-MCTd). Statistically significant higher values of GA-AP, GA-MCT, AP-MCT and anterior AP-MCTd were found in the keratoconus group (p ≤ 0.001). Moderate significant correlations of corneal aberrations (r ≥ 0.587, p < 0.001) and corneal thickness parameters (r ≤ -0.414, p < 0.001) with GA-AP and AP-MCT were found. Anterior asphericity was found to be significantly correlated with anterior and posterior AP-MCTd (r ≥ 0.430, p < 0.001). Likewise, GA-AP and AP-MCT showed a good diagnostic ability for the detection of keratoconus, with optimal cutoff values of 9.61° (sensitivity 85.5%, specificity 80.3%) and 18.08° (sensitivity 80.5%, specificity 78.7%), respectively. These new morphogeometric indices allow a clinical characterization of the 3-D structural alteration occurring in keratoconus, with less coincidence in the spatial projection of the apex and MCT points of both corneal surfaces. Future studies should confirm the potential impact on the precision of these indices of the variability of posterior corneal surface measurements obtained with Scheimpflug imaging technology.
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Affiliation(s)
- Jose S. Velázquez
- Department of Structures, Construction and Graphical Expression, Technical University of Cartagena, 30202 Cartagena, Spain
| | - Francisco Cavas
- Department of Structures, Construction and Graphical Expression, Technical University of Cartagena, 30202 Cartagena, Spain
| | - David P. Piñero
- Group of Optics and Visual Perception, Department of Optics, Pharmacology and Anatomy, University of Alicante, 03690 Alicante, Spain
| | - Francisco J.F. Cañavate
- Department of Structures, Construction and Graphical Expression, Technical University of Cartagena, 30202 Cartagena, Spain
| | - Jorge Alio del Barrio
- Division of Ophthalmology, Miguel Hernández University, 03690 Alicante, Spain
- Keratoconus Unit of Vissum Corporation Alicante, 03690 Alicante, Spain
- Department of Refractive Surgery, Vissum Corporation Alicante, 03690 Alicante, Spain
| | - Jorge L. Alio
- Division of Ophthalmology, Miguel Hernández University, 03690 Alicante, Spain
- Keratoconus Unit of Vissum Corporation Alicante, 03690 Alicante, Spain
- Department of Refractive Surgery, Vissum Corporation Alicante, 03690 Alicante, Spain
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17
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Hashemi H, Yekta A, Yazdani N, Ostadimoghaddam H, Khabazkhoob M. Comparison of Anterior Chamber Depth between Normal and Keratoconic Eyes: A Systematic Review and Meta-Analysis. J Curr Ophthalmol 2020; 32:94-98. [PMID: 32510020 PMCID: PMC7265264 DOI: 10.1016/j.joco.2019.01.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 01/11/2019] [Accepted: 01/24/2019] [Indexed: 11/30/2022] Open
Abstract
Purpose: To review the published data about changes in the anterior chamber depth (ACD) in keratoconus patients. Methods: In this systematic review and meta-analysis of observational studies, we reviewed the available and relevant literature on anterior segment changes in keratoconic eyes, with a special focus on the ACD, an effective factor in many surgical methods. Articles published up to December 2017 were identified in the following data sources: PubMed, Scopus, Ovid, ISI, ScienceDirect, and Google Scholar. Databases were comprehensively searched using the key words “Anterior Chamber Depth AND Anterior segment AND Keratoconus”. Results: A total of 496 studies including these key words were detected. Four hundred fifty-three studies were excluded, and overall 16 studies which precisely described the change in ACD were included in the literature review. The results show that with respect to the applied device, there was a statistically significant difference in ACD between keratoconic eyes and normal eyes except for Galilei analyzer. Conclusion: Summarizing the results of studies, this review revealed that ACD is significantly deeper in keratoconic eyes as compared with normal eyes, which could be explained by the steeper corneal curvature.
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Affiliation(s)
- Hassan Hashemi
- Noor Research Center for Ophthalmic Epidemiology, Noor Eye Hospital, Tehran, Iran
| | - AbbasAli Yekta
- Department of Optometry, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Negareh Yazdani
- Student Research Committee, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Hadi Ostadimoghaddam
- Refractive Errors Research Center, School of Paramedical Sciences, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Mehdi Khabazkhoob
- Department of Medical Surgical Nursing, School of Nursing and Midwifery, Shahid Beheshti University of Medical Sciences, Tehran, Iran
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18
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Correlation Between Anterior Corneal Elevation Differences in Main Meridians and Corneal Astigmatism. Eye Contact Lens 2020; 46:99-104. [DOI: 10.1097/icl.0000000000000613] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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19
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Assessment of the Association between In Vivo Corneal Morphogeometrical Changes and Keratoconus Eyes with Severe Visual Limitation. J Ophthalmol 2019; 2019:8731626. [PMID: 31662899 PMCID: PMC6778916 DOI: 10.1155/2019/8731626] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 08/06/2019] [Accepted: 08/23/2019] [Indexed: 02/06/2023] Open
Abstract
Assessing changes suffered by the cornea as keratoconus progresses has proven to be vital for this disease diagnosis and treatment. This study determines the corneal biometric profile in eyes considered as affected by keratoconus (KC) showing severe visual limitation, by means of in vivo 3D modelling techniques. This observational case series study evaluated new objective indices in 50 healthy and 30 KC corneas, following a validated protocol created by our research group, which has been previously used for diagnosis and characterization of KC in asymptomatic (preclinical) and mild visually impaired eyes. Results show a statistically significant reduction of corneal volume and an increase of total corneal area in the severe KC group, being anterior and posterior corneal surfaces minimum thickness points the best correlated parameters, although with no discrimination between groups. Receiving operator curves were used to determine sensitivity and specificity of selected indices, being anterior and posterior apex deviations the ones which reached the highest area under the curve, both with very high sensitivity (96.7% and 90%, respectively) and specificity (94.0% and 99.9%, respectively). The results suggest that once severe visual loss appears, anterior corneal topography should be considered for a more accurate diagnosis of clinical KC, being anterior apex deviation the key metric discriminant. This study can be a useful tool for KC classification, helping doctors in diagnosing severe cases of the disease, and can help to characterize corneal changes that appear when severe KC is developed and how they relate with vision deterioration.
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20
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Pellucid marginal degeneration: Detection, discrimination from other corneal ectatic disorders and progression. Cont Lens Anterior Eye 2019; 42:341-349. [DOI: 10.1016/j.clae.2018.11.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 11/07/2018] [Accepted: 11/15/2018] [Indexed: 02/07/2023]
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21
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Differences in corneo-scleral topographic profile between healthy and keratoconus corneas. Cont Lens Anterior Eye 2019; 42:75-84. [DOI: 10.1016/j.clae.2018.05.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Revised: 05/11/2018] [Accepted: 05/17/2018] [Indexed: 11/20/2022]
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22
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Cavas-Martínez F, Fernández-Pacheco DG, Parras D, Cañavate FJF, Bataille L, Alió J. Study and characterization of morphogeometric parameters to assist diagnosis of keratoconus. Biomed Eng Online 2018; 17:161. [PMID: 30458789 PMCID: PMC6245489 DOI: 10.1186/s12938-018-0564-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Background In case of significant imperfections on the cornea, data acquisition is difficult and a significant level of missing data could require the interpolation of important areas of the cornea, resulting in a very ambiguous model. The development of methods to define in vivo customised geometric properties of the cornea based only on real raw data is extremely useful to diagnose and assess the progression of diseases directly related to the corneal architecture. The present work tries to improve the prognostic of corneal ectasia creating a 3D customised model of the cornea and analysing different geometric variables from this model to determine which variables or combination of them could be defined as an indicator of susceptibility to develop keratoconus. Methods A corneal geometric reconstruction was performed using zonal functions and retrospective Scheimpflug tomography data from 187 eyes of 187 patients. Morphology of healthy and keratoconic corneas was characterized by means of geometric variables. The performance of these variables as predictors of a new geometric marker was assessed and their correlations were analysed. Results The more representative variable to classify the corneal anomalies related to keratoconus was posterior apex deviation (area under receiver operating characteristic curve > 0.899; p < 0.0001). However, the strongest correlations in both healthy and pathological corneas were provided by the metrics directly related to the thickness, as deviations of the anterior/posterior minimum thickness points. Conclusions The presented morphogeometric approach based on the analysis and custom geometric modelling of the cornea demonstrates to be useful for the characterization and diagnosis of keratoconus disease, stating that geometrical deformation is an effective marker of the ectatic disease’s progression.
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Affiliation(s)
- Francisco Cavas-Martínez
- Department of Graphical Expression, Technical University of Cartagena, C/Doctor Fleming s/n, 30202, Cartagena, Murcia, Spain.
| | - Daniel G Fernández-Pacheco
- Department of Graphical Expression, Technical University of Cartagena, C/Doctor Fleming s/n, 30202, Cartagena, Murcia, Spain
| | - Dolores Parras
- Department of Graphical Expression, Technical University of Cartagena, C/Doctor Fleming s/n, 30202, Cartagena, Murcia, Spain
| | - Francisco J F Cañavate
- Department of Graphical Expression, Technical University of Cartagena, C/Doctor Fleming s/n, 30202, Cartagena, Murcia, Spain
| | - Laurent Bataille
- Research and Development Department, Vissum Corporation Alicante, Alicante, Spain
| | - Jorge Alió
- Division of Ophthalmology, Universidad Miguel Hernández, Alicante, Spain.,Keratoconus Unit of Vissum Corporation Alicante, Alicante, Spain.,Department of Refractive Surgery, Vissum Corporation Alicante, Alicante, Spain
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Huseynli S, Salgado-Borges J, Alio JL. Comparative evaluation of Scheimpflug tomography parameters between thin non-keratoconic, subclinical keratoconic, and mild keratoconic corneas. Eur J Ophthalmol 2018; 28:521-534. [PMID: 29566542 DOI: 10.1177/1120672118760146] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
PURPOSE To evaluate and compare the topographic and topometric parameters, thickness profile data, and data from enhanced elevation maps of thin non-keratoconic, subclinical keratoconic, and mild keratoconic corneas with the Pentacam Scheimpflug corneal tomography and to study the usefulness of different parameters to differentiate keratoconus from topographically normal thin corneas. METHODS The study included 30 eyes with subclinical keratoconus, 30 eyes with mild-stage keratoconus, and 54 healthy eyes with minimal pachymetry ≤500 µm, with a mean age of 21.19 ± 2.97, 21.75 ± 1.93, and 21.5 ± 2.95 years, respectively. The area under the receiver operating characteristic curves was used to analyze the diagnostic significance of the Pentacam parameters. RESULTS The anterior and posterior corneal elevations, pachymetric progression, the percentage of thickness increase measurements, overall D value, and topometric indices were statistically significantly higher in subclinical and mild keratoconic corneas than in normal eyes with thin cornea (p < 0.05). All these parameters had sufficient strength (area under the receiver operating characteristic curves >0.90) to differentiate clinical keratoconus. Posterior elevation showed the excellent area under the receiver operating characteristic curves with 100% sensitivity and 100% specificity for this purpose. However, among all parameters studied, the anterior elevation (0.935) showed the excellent area under the receiver operating characteristic curves to differentiate subclinical keratoconus, followed by posterior elevation (0.897), index of height decentration (0.887), and D value (0.882). CONCLUSION The parameters derived from the Scheimpflug device, such as corneal elevations and overall D value, can effectively differentiate subclinical and clinical keratoconus from non-keratoconic thin cornea eyes. However, the specificity levels of these parameters were relatively limited in the diagnosis of subclinical keratoconus.
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Affiliation(s)
- Samira Huseynli
- 1 National Ophthalmology Center named after academician Zarifa Aliyeva, Baku, Azerbaijan
| | | | - Jorge L Alio
- 3 Vissum Instituto Oftalmologico de Alicante, Universidad Miguel Hernandez, Alicante, Spain
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24
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A Study for Parametric Morphogeometric Operators to Assist the Detection of Keratoconus. Symmetry (Basel) 2017. [DOI: 10.3390/sym9120302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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25
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Bozkurt B, Yılmaz M, Meşen A, Kamış Ü, Ekinci Köktekir B, Okudan S. Correlation of Corneal Endothelial Cell Density with Corneal Tomographic Parameters in Eyes with Keratoconus. Turk J Ophthalmol 2017; 47:255-260. [PMID: 29109893 PMCID: PMC5661174 DOI: 10.4274/tjo.22800] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Accepted: 03/24/2017] [Indexed: 12/01/2022] Open
Abstract
Objectives: To examine changes in corneal endothelial cell density (ECD) in different stages of keratoconus and evaluate its correlation with corneal tomographic parameters. Materials and Methods: Two hundred six patients with keratoconus were enrolled in the study. Corneal topography was performed by Sirius (CSO, Italy), which has a rotating Scheimpflug camera and a Placido disc topographer. Automatic endothelial analysis was done with the non-contact endothelial microscope (20x probe) of Confoscan-4 (NIDEK, Japan). The eyes were classified into stages based on steepest keratometric value as follows: mild <45 D; moderate 45-52 D; severe >52 D and according to thinnest cornea thickness (TCT) as <400 μm, 400-450 μm, and >450 μm. Tomographic and endothelial cell parameters were compared among the groups using Kruskal-Wallis test and the correlations between them were analyzed using Spearman correlation. Results: The study included 391 eyes of 100 male (24.29±7.7 years, range 11-47 years) and 106 female (26.26±7.5 years, range 13-45 years) patients (p=0.07). Mean ECD values were 2628±262 cells/mm2, 2541.9±260.4 cells/mm2, and 2414.6±384.3 cells/mm2 in mild, moderate, and severe keratoconus, respectively (p<0.001) and 2592.3±277 cells/mm2, 2502±307 cells/mm2 and 2348±296 cells/mm2 in corneas with TCT values >450 µm, 400-450 µm, and <400 µm, respectively (p<0.001). ECD showed significant negative correlation with keratometric and elevation parameters and positive correlation with pachymetric parameters (p<0.05). Conclusion: As endothelial cell numbers seem to decrease with the progression of keratoconus, specular/confocal microscopy screening should be carried out, especially in eyes with advanced stages and corneas with TCT <400 µm.
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Affiliation(s)
- Banu Bozkurt
- Selçuk University Faculty of Medicine, Department of Ophthalmology, Konya, Turkey
| | - Mevlüt Yılmaz
- Dr. Munif İslamoğlu State Hospital, Ophthalmology Clinic, Kastamonu, Turkey
| | - Ali Meşen
- Selçuk University Faculty of Medicine, Department of Ophthalmology, Konya, Turkey
| | - Ümit Kamış
- Dünyagöz Hospital, Ophthalmology Clinic, Konya, Turkey
| | | | - Süleyman Okudan
- Selçuk University Faculty of Medicine, Department of Ophthalmology, Konya, Turkey
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A new approach to keratoconus detection based on corneal morphogeometric analysis. PLoS One 2017; 12:e0184569. [PMID: 28886157 PMCID: PMC5590974 DOI: 10.1371/journal.pone.0184569] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Accepted: 08/26/2017] [Indexed: 01/16/2023] Open
Abstract
Purpose To characterize corneal structural changes in keratoconus using a new morphogeometric approach and to evaluate its potential diagnostic ability. Methods Comparative study including 464 eyes of 464 patients (age, 16 and 72 years) divided into two groups: control group (143 healthy eyes) and keratoconus group (321 keratoconus eyes). Topographic information (Sirius, CSO, Italy) was processed with SolidWorks v2012 and a solid model representing the geometry of each cornea was generated. The following parameters were defined: anterior (Aant) and posterior (Apost) corneal surface areas, area of the cornea within the sagittal plane passing through the Z axis and the apex (Aapexant, Aapexpost) and minimum thickness points (Amctant, Amctpost) of the anterior and posterior corneal surfaces, and average distance from the Z axis to the apex (Dapexant, Dapexpost) and minimum thickness points (Dmctant, Dmctpost) of both corneal surfaces. Results Significant differences among control and keratoconus group were found in Aapexant, Aapexpost, Amctant, Amctpost, Dapexant, Dapexpost (all p<0.001), Apost (p = 0.014), and Dmctpost (p = 0.035). Significant correlations in keratoconus group were found between Aant and Apost (r = 0.836), Amctant and Amctpost (r = 0.983), and Dmctant and Dmctpost (r = 0.954, all p<0.001). A logistic regression analysis revealed that the detection of keratoconus grade I (Amsler Krumeich) was related to Apost, Atot, Aapexant, Amctant, Amctpost, Dapexpost, Dmctant and Dmctpost (Hosmer-Lemeshow: p>0.05, R2 Nagelkerke: 0.926). The overall percentage of cases correctly classified by the model was 97.30%. Conclusions Our morphogeometric approach based on the analysis of the cornea as a solid is useful for the characterization and detection of keratoconus.
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Martínez-Abad A, Piñero DP. New perspectives on the detection and progression of keratoconus. J Cataract Refract Surg 2017; 43:1213-1227. [DOI: 10.1016/j.jcrs.2017.07.021] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 06/03/2017] [Accepted: 07/07/2017] [Indexed: 12/26/2022]
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28
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Camps VJ, Piñero DP, Caravaca E, De Fez D. Preliminary validation of an optimized algorithm for intraocular lens power calculation in keratoconus. Indian J Ophthalmol 2017; 65:690-699. [PMID: 28820154 PMCID: PMC5598179 DOI: 10.4103/ijo.ijo_274_16] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Purpose: This study aimed to evaluate the theoretical influence on intraocular lens power (PIOL) calculation of the use of keratometric approach for corneal power (Pc) calculation in keratoconus and to develop and validate an algorithm preliminarily to minimize this influence. Methods: Pc was calculated theoretically with the classical keratometric approach, the Gaussian equation, and the keratometric approach using a variable keratometric index (nkadj) dependent on r1c(Pkadj). Differences in PIOL calculations (ΔPIOL) using keratometric and Gaussian Pc values were evaluated. Preliminary clinical validation of a PIOL algorithm using Pkadj was performed in 13 keratoconus eyes. Results: PIOL underestimation was present if Pc was overestimated, and vice versa. Theoretical PIOL overestimation up to −5.6 D and −6.2 D using Le Grand and Gullstrand eye models was found for a keratometric index of 1.3375. If nkadj was used, maximal Δ PIOL was ±1.1 D, with most of the values ≤±0.6 D. Clinically, PIOL under- and over-estimations ranged from −1.1 to − 0.4 D. No statistically significant differences were found between PIOL obtained with Pkadj and Gaussian equation (P > 0.05). Conclusion: The use of the keratometric Pc for PIOL calculations in keratoconus can lead to significant errors that may be minimized using a Pkadj approach.
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Affiliation(s)
- Vicente J Camps
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
| | - David P Piñero
- Department of Optics, Pharmacology and Anatomy, University of Alicante; Department of Ophthalmology (Oftalmar), Vithas Medimar International Hospital, Alicante, Spain
| | - Esteban Caravaca
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
| | - Dolores De Fez
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
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Martínez-Abad A, Piñero DP, Ruiz-Fortes P, Artola A. Evaluation of the diagnostic ability of vector parameters characterizing the corneal astigmatism and regularity in clinical and subclinical keratoconus. Cont Lens Anterior Eye 2017; 40:88-96. [DOI: 10.1016/j.clae.2016.11.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 11/12/2016] [Accepted: 11/28/2016] [Indexed: 10/20/2022]
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Cavas-Martínez F, Fernández-Pacheco DG, De la Cruz-Sánchez E, Nieto Martínez J, Fernández Cañavate FJ, Vega-Estrada A, Plaza-Puche AB, Alió JL. Geometrical custom modeling of human cornea in vivo and its use for the diagnosis of corneal ectasia. PLoS One 2014; 9:e110249. [PMID: 25329896 PMCID: PMC4201525 DOI: 10.1371/journal.pone.0110249] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 09/14/2014] [Indexed: 11/18/2022] Open
Abstract
AIM To establish a new procedure for 3D geometric reconstruction of the human cornea to obtain a solid model that represents a personalized and in vivo morphology of both the anterior and posterior corneal surfaces. This model is later analyzed to obtain geometric variables enabling the characterization of the corneal geometry and establishing a new clinical diagnostic criterion in order to distinguish between healthy corneas and corneas with keratoconus. METHOD The method for the geometric reconstruction of the cornea consists of the following steps: capture and preprocessing of the spatial point clouds provided by the Sirius topographer that represent both anterior and posterior corneal surfaces, reconstruction of the corneal geometric surfaces and generation of the solid model. Later, geometric variables are extracted from the model obtained and statistically analyzed to detect deformations of the cornea. RESULTS The variables that achieved the best results in the diagnosis of keratoconus were anterior corneal surface area (ROC area: 0.847, p<0.000, std. error: 0.038, 95% CI: 0.777 to 0.925), posterior corneal surface area (ROC area: 0.807, p<0.000, std. error: 0.042, 95% CI: 0,726 to 0,889), anterior apex deviation (ROC area: 0.735, p<0.000, std. error: 0.053, 95% CI: 0.630 to 0.840) and posterior apex deviation (ROC area: 0.891, p<0.000, std. error: 0.039, 95% CI: 0.8146 to 0.9672). CONCLUSION Geometric modeling enables accurate characterization of the human cornea. Also, from a clinical point of view, the procedure described has established a new approach for the study of eye-related diseases.
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Affiliation(s)
- Francisco Cavas-Martínez
- Department of Graphical Expression, Technical University of Cartagena, Cartagena, Spain
- * E-mail:
| | | | | | - José Nieto Martínez
- Department of Graphical Expression, Technical University of Cartagena, Cartagena, Spain
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New approach for correction of error associated with keratometric estimation of corneal power in keratoconus. Cornea 2014; 33:960-7. [PMID: 25090162 DOI: 10.1097/ico.0000000000000190] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [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 obtain the exact value of the keratometric index (nkexact) and to clinically validate a variable keratometric index (nkadj) that minimizes this error. METHODS The nkexact value was determined by obtaining differences (ΔPc) between keratometric corneal power (Pk) and Gaussian corneal power ((Equation is included in full-text article.)) equal to 0. The nkexact was defined as the value associated with an equivalent difference in the magnitude of ΔPc for extreme values of posterior corneal radius (r2c) for each anterior corneal radius value (r1c). This nkadj was considered for the calculation of the adjusted corneal power (Pkadj). Values of r1c ∈ (4.2, 8.5) mm and r2c ∈ (3.1, 8.2) mm were considered. Differences of True Net Power with (Equation is included in full-text article.), Pkadj, and Pk(1.3375) were calculated in a clinical sample of 44 eyes with keratoconus. RESULTS nkexact ranged from 1.3153 to 1.3396 and nkadj from 1.3190 to 1.3339 depending on the eye model analyzed. All the nkadj values adjusted perfectly to 8 linear algorithms. Differences between Pkadj and (Equation is included in full-text article.)did not exceed ±0.7 D (Diopter). Clinically, nk = 1.3375 was not valid in any case. Pkadj and True Net Power and Pk(1.3375) and Pkadj were statistically different (P < 0.01), whereas no differences were found between (Equation is included in full-text article.)and Pkadj (P > 0.01). CONCLUSIONS The use of a single value of nk for the calculation of the total corneal power in keratoconus has been shown to be imprecise, leading to inaccuracies in the detection and classification of this corneal condition. Furthermore, our study shows the relevance of corneal thickness in corneal power calculations in keratoconus.
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Sergienko NM, Shargorodska IV. Corneal biomechanical property measurement with an IOP loading method in keratoconic patients. Curr Eye Res 2014; 39:994-9. [PMID: 24654976 DOI: 10.3109/02713683.2014.891751] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE To study the biomechanical properties of the corneas of both eyes in patients with evident keratoconus manifestation in one eye. METHODS Our study consisted of nine patients with keratoconus and 25 volunteers in the control group. Both eyes of all participants were measured twice with a Pentacam Scheimpflug system: first with the standard Scheimpflug system and subsequently with the original version of the same technique in combination with a new device that can generate experimental artificial intraocular pressure (IOP) elevation. Diagnoses of keratoconus or non-keratoconus were made using the Pentacam Scheimpflug system software (StatSoft, Inc., Tulsa, OK). RESULTS The artificially elevated IOP caused bulging of the anterior corneal surface in both eyes of keratoconic patients and a small flattening of the cornea in the eyes of the control group. Corneal ectasia, expressed in terms of diopters, during IOP loading in both keratoconic and nominally unaffected eyes was 4.12 D and 1.37 D, respectively. The changes were statistically significant (p < 0.05). Our dynamic study revealed a distinct weakness of the corneal tissue and an inability of keratoconic and contralateral eyes to resist IOP elevation. CONCLUSION The IOP loading method permits evaluation of the biomechanical properties of the cornea across its entire surface. All nine contralateral unaffected eyes in patients with a diagnosis of unilateral keratoconus presented weak biomechanical properties and in fact should be considered as forme fruste keratoconus.
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Affiliation(s)
- Nikolai M Sergienko
- Department of ophthalmology, National Medical Academy of Postgraduate education , Kyiv , Ukraine
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