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Al-Sharify NT, Nser HY, Ghaeb NH, Al-Sharify ZT, See OH, Weng LY, Ahmed SM. Influence of different parameters on the corneal asphericity (Q value) assessed with progress in biomedical optics and imaging - A review. Heliyon 2024; 10:e35924. [PMID: 39224364 PMCID: PMC11367468 DOI: 10.1016/j.heliyon.2024.e35924] [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: 04/19/2023] [Revised: 07/20/2024] [Accepted: 08/06/2024] [Indexed: 09/04/2024] Open
Abstract
The corneal eye diseases such as Keratoconus cause weakening of the cornea, with this disease the cornea can change in shape. This condition affects between 1 in 3,000 to 1 in 10,000 people. The main reason for the development of such conditions is unknown and can have significant impacts. Over the last decade, with advancements in computerized corneal topography assessments, researchers have increasingly expressed interest in corneal topography for research as well as clinical activities. Up till now, several aspheric numerical models have been developed as well as proposed to define the complex shape of the cornea. A commonly used term for characterizing the asphericity in an eye is the Q value, a common indicator of the aspherical degree of the cornea. It is one of the critical parameters in the mathematical description model of the cornea as it represents the cornea's shape and the eye's characteristics. Due to the utmost importance of this Q value of the cornea, a couple of studies have attempted to explore this parameter and its distribution, merely in terms of its influence on the human eye's optical properties. The corneal Q value is an important factor that needs to be determined to treat for any refractive errors as corneal degeneration are disease that can lead to potential problems with the structure of the cornea. This study aims to highlight the need to understand Q value of the cornea as this can essentially assist with personalising corneal refractive surgeries and implantation of intraocular lenses. Therefore, the relevance of corneal Q value must be studied in association with different patients, especially ones who have been diagnosed with cataracts, brain tumours, or even COVID-19. To address this issue, this paper first carries out a literature review on the optics of the cornea, the relevance of corneal Q value in ophthalmic practice and studies corneal degenerations and its causes. Thereafter, a detailed review of several noteworthy relevant research studies examining the Q value of the cornea is performed. To do so, an elaborate database is created, which presents a list of different research works examined in this study and provides key evidence derived from these studies. This includes listing details on the age, gender, ethnicity of the eyes assessed, the control variables, the technology used in the study, and even more. The database also delivers important findings and conclusions noted in each study assessed. Next, this paper analyses and discusses the magnitude of corneal Q value in various scenarios and the influence of different parameters on corneal Q value. To design visual optical products as well as to enhance the understanding of the optical properties of an eye, future studies could consider the database and work presented in this study as useful references. In addition, the work can be used to make informed decisions in clinical practice for designing visual optical products as well as to enhance the understanding of the optical properties of an Eye.
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Affiliation(s)
- Noor T. Al-Sharify
- Department of Electrical & Electronic Engineering, College of Engineering, Universiti Tenaga Nasional, Malaysia
- Medical Instrumentation Engineering Department, Al-Esraa University College, Baghdad, Iraq
| | - Husam Yahya Nser
- Department of Electrical & Electronic Engineering, College of Engineering, Universiti Tenaga Nasional, Malaysia
| | - Nebras H. Ghaeb
- Biomedical Engineering Department, Al Khawarezmi, Engineering College, University of Baghdad, Iraq
| | - Zainab T. Al-Sharify
- Department of Pharmacy, Al Hikma University College, Baghdad, Iraq
- School of Chemical Engineering, University of Birmingham, Edgbaston, B15 2TT, Birmingham, United Kingdom
| | - Ong Hang See
- Department of Electrical & Electronic Engineering, College of Engineering, Universiti Tenaga Nasional, Malaysia
| | - Leong Yeng Weng
- Department of Electrical & Electronic Engineering, College of Engineering, Universiti Tenaga Nasional, Malaysia
| | - Sura M. Ahmed
- Department of Electrical & Electronic Engineering, College of Engineering, Universiti Tenaga Nasional, Malaysia
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Feng Y, Nitter T, Bertelsen G, Stojanovic A. Repeatability and agreement of total corneal astigmatism measured in keratoconic eyes using four current devices. Clin Exp Ophthalmol 2024. [PMID: 39034272 DOI: 10.1111/ceo.14423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2024] [Revised: 07/08/2024] [Accepted: 07/09/2024] [Indexed: 07/23/2024]
Abstract
BACKGROUND To evaluate repeatability and agreement in measurements of total corneal astigmatism (TCA) in keratoconic eyes, using four optical coherence tomography (OCT)-based devices: Anterion, Casia SS-1000, IOLMaster 700, and MS-39. METHODS Three consecutive measurements were taken with each device in 136 eyes. TCA values were converted into components J0 and J45. The Anterion and the IOLMaster 700 also provided axial length (AL) measurements. The repeatability was calculated using pooled within-subject standard deviation (Sw). The agreement among the four devices was assessed by pairwise comparisons and Bland-Altman plots. RESULTS For all devices, the repeatability of TCA measurements showed Sw ≤0.23 D for TCA magnitude, ≤0.14 D for J0, and ≤0.12 D for J45. There were statistically significant differences in TCA magnitude for each pair, except for IOLMaster 700 with MS-39, and Anterion with MS-39. The repeatability (Sw) of axis measurements had a statistically significant negative correlation with the TCA magnitude (p < 0.001 for all devices). Both Anterion and IOLMaster 700 had high repeatability in AL measurements (Sw: 0.007 mm for Anterion and 0.009 mm for IOLMaster 700). The difference in AL between the two was 0.015 ± 0.033 mm (p < 0.001). CONCLUSIONS All four devices showed good repeatability in TCA measurements in keratoconic eyes, the agreement for TCA measurements between the tested devices was generally low. Anterion and IOLMaster 700 showed good repeatability and agreement in AL measurements.
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Affiliation(s)
- Yue Feng
- Institute of Community Medicine, Faculty of Health Sciences, University in Tromsø, Tromsø, Norway
| | | | - Geir Bertelsen
- Institute of Community Medicine, Faculty of Health Sciences, University in Tromsø, Tromsø, Norway
- Department of Ophthalmology, University Hospital North Norway, Tromsø, Norway
| | - Aleksandar Stojanovic
- Department of Ophthalmology, University Hospital North Norway, Tromsø, Norway
- Institute of Clinical Medicine, Faculty of Health Sciences, University in Tromsø, Tromsø, Norway
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Wang Q, Chen Y, Shen K, Zhou X, Shen M, Lu F, Zhu D. Spatial mapping of corneal biomechanical properties using wave-based optical coherence elastography. JOURNAL OF BIOPHOTONICS 2024; 17:e202300534. [PMID: 38453148 DOI: 10.1002/jbio.202300534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 01/20/2024] [Accepted: 02/11/2024] [Indexed: 03/09/2024]
Abstract
Quantifying the mechanical properties of the cornea can provide valuable insights into the occurrence and progression of keratoconus, as well as the effectiveness of corneal crosslinking surgery. This study presents a non-contact and non-invasive wave-based optical coherence elastography system that utilizes air-pulse stimulation to create a two-dimensional map of corneal elasticity. Homogeneous and dual concentration phantoms were measured with the sampling of 25 × 25 points over a 6.6 × 6.6 mm2 area, to verify the measurement capability for elastic mapping and the spatial resolution (0.91 mm). The velocity of elastic waves distribution of porcine corneas before and after corneal crosslinking surgery were further mapped, showing a significant change in biomechanics in crosslinked region. This system features non-invasiveness and high resolution, holding great potential for application in ophthalmic clinics.
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Affiliation(s)
- Qingying Wang
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Yulei Chen
- Department of Ophthalmology, Dongguan Tungwah Hospital, Dongguan, China
| | - Kexin Shen
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Xingyu Zhou
- Eye Hospital and School of Ophthalmology and Optometry, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Meixiao Shen
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Fan Lu
- State Key Laboratory of Ophthalmology, Optometry and Visual Science, Eye Hospital, Wenzhou Medical University, Wenzhou, China
- National Clinical Research Center for Ocular Diseases, Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - Dexi Zhu
- National Engineering Research Center of Ophthalmology and Optometry, Eye Hospital, Wenzhou Medical University, Wenzhou, China
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Gómez C, Piñero DP, Alió JL, Cavas F. Comparative evaluation of methods for obtaining the stress-free geometry of keratoconus corneas with different levels of severity. Comput Biol Med 2024; 170:107870. [PMID: 38217971 DOI: 10.1016/j.compbiomed.2023.107870] [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: 07/27/2023] [Revised: 12/07/2023] [Accepted: 12/17/2023] [Indexed: 01/15/2024]
Abstract
A biomechanical model that simulates the physiological pressure load on the cornea without considering the stresses in vivo will result in an overstress or underestimation of the stress field and incorrect deformation of the corneal structure. Therefore, it is essential to propose numerical models that consider the stress-free geometry of the cornea. In this study, the Displacement and Pre-stress methods were compared to obtain the stress-free geometry (S-FG) and the physiological estimated geometry (P-EG), based on the patient-specific geometric behavior and the computational time required to reach each geometry. The same shape and contour conditions were considered in the models obtained from both methods for each of the pathological scenarios analyzed. Both methods behaved differently to obtain the free geometry, and this difference increased with the severity grade of the disease. However, they behaved in a similar way to reach the physiological estimated geometry. The Displacement method required a lower computational cost to reach the free geometry, with both methods presenting a similar computational cost to obtain the physiological geometry. The stress-free geometries obtained by both methods allowed to characterize the existing biomechanical decompensation during the progression of the diseases. In conclusion, the calculation of the stress-free corneal geometry associated to the clinically measured intraocular pressure with the Displacement and Prestress Methods in keratoconus eyes allows the development of accurate and useable models in clinical practice in real time. This displacement method shows some benefits in terms of computational cost.
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Affiliation(s)
- Carmelo Gómez
- International School of Doctorate, Technical University of Cartagena, 30202, Cartagena, Spain
| | - David P Piñero
- Department of Optics, Pharmacology and Anatomy, University of Alicante, 03690, Alicante, Spain
| | - Jorge L Alió
- Cornea, Cataract and Refractive Surgery Department, VISSUM, Alicante, Spain; Division of Ophthalmology, Department of Pathology and Surgery, Faculty of Medicine, Miguel Hernández University, Alicante, Spain
| | - Francisco Cavas
- Department of Structures, Construction and Graphic Expression, Technical University of Cartagena, 30202, Cartagena, Spain.
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Vaccaro S, Vivarelli C, Yu AC, Pecora N, Lionetti G, Gioia R, Scorcia V, Giannaccare G. Longitudinal Changes of Cornea Volume Measured by Means of Anterior Segment-Optical Coherence Tomography in Patients with Stable and Progressive Keratoconus. Life (Basel) 2024; 14:176. [PMID: 38398685 PMCID: PMC10890364 DOI: 10.3390/life14020176] [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: 12/10/2023] [Revised: 01/19/2024] [Accepted: 01/22/2024] [Indexed: 02/25/2024] Open
Abstract
Keratoconus is a corneal disease which results in progressive thinning and protrusion of the cornea leading to irregular astigmatism. The purpose of this study was to evaluate longitudinal changes in corneal volume (CV) occurring over time in keratoconus eyes. Consecutive patients affected by keratoconus were evaluated by means of anterior segment-optical coherence tomography (AS-OCT) at two different time points: baseline (T0) and after 1 year (T1). Anterior and posterior refractive value; corneal thickness at the thinnest point (TP) and corneal volume (CV) calculated within discs of 3, 5 and 8 mm of diameter; anterior chamber depth (ACD); and anterior chamber volume (ACV) were obtained. Enrolled patients were divided into 3 groups (groups 1, 2, 3) according to the increasing disease severity and into 2 groups (groups A, B) according to the progression or stability of the disease. Overall, 116 eyes of 116 patients (76 males and 40 females, mean age 34.76 ± 13.99 years) were included. For the entire group of keratoconus patients, in comparison with T0, mean TP decreased at T1 from 458.7 ± 52.2 µm to 454.6 ± 51.6 µm (p = 0.0004); in parallel, mean value of CV calculated at 5 mm and 8 mm decreased significantly (from 10.78 ± 0.8 at T0 to 10.75 ± 0.79 at T1 (p = 0.02), and from 32.03 ± 2.01 mm3 at T0 to 31.95 ± 1.98 at T1 (p = 0.02), respectively). Conversely, there were no statistically significant differences in CV at 3 mm from T0 to T1 (p = 0.08), as well as for ACD and ACV. Regarding the course of the disease, patients belonging to group A showed statistically significant differences from T0 to T1 for TP, and for CV at 3 mm, 5 mm and 8 mm (p < 0.0001, p < 0.0001, p < 0.001 and p = 0.0058 respectively). There were no statistically significant differences for ACD (p = 0.6916) and ACV calculated at 3, 5 and 8 mm (p = 0.7709, p = 0.3765, p = 0.2475, respectively) in group A. At the same time, no statistically significant differences for ACD (p = 0.2897) and ACV calculated at 3, 5 and 8 mm (p = 0.9849, p = 0.6420, p = 0.8338, respectively) were found in group B. There were statistically significant positive correlations between changes of TP and CV at 3 mm (r = 0.6324, p < 0.0001), 5 mm (r = 0.7622, p < 0.0001) and 8 mm (r = 0.5987 p < 0.0001). In conclusion, given the strong correlation with TP, CV might be considered an additional AS-OCT parameter to be used in association with conventional parameters when detecting longitudinal changes in keratoconic eyes.
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Affiliation(s)
- Sabrina Vaccaro
- Department of Ophthalmology, University Magna Græcia of Catanzaro, 88100 Catanzaro, Italy; (S.V.); (N.P.); (G.L.); (R.G.); (V.S.)
| | - Chiara Vivarelli
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy; (C.V.); (A.C.Y.)
- Department of Ophthalmology, Ospedali Privati Forlì “Villa Igea”, 47122 Forlì, Italy
| | - Angeli Christy Yu
- Department of Translational Medicine, University of Ferrara, 44121 Ferrara, Italy; (C.V.); (A.C.Y.)
- Department of Ophthalmology, Ospedali Privati Forlì “Villa Igea”, 47122 Forlì, Italy
| | - Nicolò Pecora
- Department of Ophthalmology, University Magna Græcia of Catanzaro, 88100 Catanzaro, Italy; (S.V.); (N.P.); (G.L.); (R.G.); (V.S.)
| | - Giovanna Lionetti
- Department of Ophthalmology, University Magna Græcia of Catanzaro, 88100 Catanzaro, Italy; (S.V.); (N.P.); (G.L.); (R.G.); (V.S.)
| | - Raffaella Gioia
- Department of Ophthalmology, University Magna Græcia of Catanzaro, 88100 Catanzaro, Italy; (S.V.); (N.P.); (G.L.); (R.G.); (V.S.)
| | - Vincenzo Scorcia
- Department of Ophthalmology, University Magna Græcia of Catanzaro, 88100 Catanzaro, Italy; (S.V.); (N.P.); (G.L.); (R.G.); (V.S.)
| | - Giuseppe Giannaccare
- Eye Clinic, Department of Surgical Sciences, University of Cagliari, Via Università 40, 09124 Cagliari, Italy
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Yuhas PT, Fortman MM, Mahmoud AM, Roberts CJ. Keratoconus cone location influences ocular biomechanical parameters measured by the Ocular Response Analyzer. EYE AND VISION (LONDON, ENGLAND) 2024; 11:2. [PMID: 38167119 PMCID: PMC10763366 DOI: 10.1186/s40662-023-00371-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 12/09/2023] [Indexed: 01/05/2024]
Abstract
BACKGROUND Keratoconus is characterized by asymmetry in the biomechanical properties of the cornea, with focal weakness in the area of cone formation. We tested the hypothesis that centrally-measured biomechanical parameters differ between corneas with peripheral cones and corneas with central cones. METHODS Fifty participants with keratoconus were prospectively recruited. The mean ± standard deviation age was 38 ± 13 years. Axial and tangential corneal topography were analyzed in both eyes, if eligible. Cones in the central 3 mm of the cornea were considered central, and cones outside the central 3 mm were considered peripheral. Each eye was then measured with the Ocular Response Analyzer (ORA) tonometer. T-tests compared differences in ORA-generated waveform parameters between cohorts. RESULTS Seventy-eight eyes were analyzed. According to the axial topography maps, 37 eyes had central cones and 41 eyes had peripheral cones. According to the tangential topography maps, 53 eyes had central cones, and 25 eyes had peripheral cones. For the axial-topography algorithm, wave score (WS) was significantly higher in peripheral cones than central cones (inter-cohort difference = 1.27 ± 1.87). Peripheral cones had a significantly higher area of first peak, p1area (1047 ± 1346), area of second peak, p2area (1130 ± 1478), height of first peak, h1 (102 ± 147), and height of second peak, h2 (102 ± 127), than central cones. Corneal hysteresis (CH), width of the first peak, w1, and width of the second peak, w2, did not significantly differ between cohorts. There were similar results for the tangential-topography algorithm, with a significant difference between the cohorts for p1area (855 ± 1389), p2area (860 ± 1531), h1 (81.7 ± 151), and h2 (92.1 ± 131). CONCLUSIONS Cone location affects the biomechanical response parameters measured under central loading of the cornea. The ORA delivers its air puff to the central cornea, so the fact that h1 and h2 and that p1area and p2area were smaller in the central cone cohort than in the peripheral cone cohort suggests that corneas with central cones are softer or more compliant centrally than corneas with peripheral cones, which is consistent with the location of the pathology. This result is evidence that corneal weakening in keratoconus is focal in nature and is consistent with localized disruption of lamellar orientation.
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Affiliation(s)
- Phillip T Yuhas
- College of Optometry, The Ohio State University, Columbus, OH, USA
| | | | - Ashraf M Mahmoud
- Department of Ophthalmology and Visual Sciences, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Cynthia J Roberts
- Department of Ophthalmology and Visual Sciences, College of Medicine, The Ohio State University, Columbus, OH, USA.
- Department of Biomedical Engineering, College of Engineering, The Ohio State University, Columbus, OH, USA.
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Owusu S, Zaabaar E, Kwarteng MA, Ankamah S, Abowine JBV, Kyei S. Scheimpflug-Derived Keratometric, Pachymetric and Pachymetric Progression Indices in the Diagnosis of Keratoconus: A Systematic Review and Meta-Analysis. Clin Ophthalmol 2023; 17:3941-3964. [PMID: 38143558 PMCID: PMC10749111 DOI: 10.2147/opth.s436492] [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: 08/22/2023] [Accepted: 12/07/2023] [Indexed: 12/26/2023] Open
Abstract
Scheimpflug Pentacam Tomography is becoming crucial in the diagnosis and monitoring of keratoconus, as well as in pre- and post-corneal refractive care, but there are still some inconsistencies surrounding its evidence base diagnostic outcome. Therefore, this study aimed at employing meta-analysis to systematically evaluate the keratometric, pachymetric, and pachymetric progression indices used in the diagnosis of Keratoconus. The review protocol was registered with PROSPERO (Identifier: CRD4202310058) and followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. PubMed, MEDLINE, Web of Science, and EMBASE were used for data search, followed by a quality appraisal of the included studies using the revised tool for the quality assessment of diagnostic accuracy studies (QUADAS-2). Meta-analysis was conducted using the meta (6.5.0) and metafor (4.2.0) packages in R version 4.3.0, as well as Stata. A total of 32 studies were included in the analysis. All keratometry (K) readings (flattest meridian, K1; steepest meridian, K2, maximum, Kmax) were significantly steeper in keratoconic compared to normal eyes: [MD (95% CI)], K1 [2.67 (1.81; 3.52)], K1-back [-0.71 (-1.03; -0.39)], K1-front [4.06 (2.48; 5.63)], K2 [4.32 (2.89; 5.75)], K2-back [-1.25 (-1.68; -0.82)], K2-front [4.82 (1.88; 7.76)], Kmax [7.57 (4.80; 10.34)], and Kmean [2.80 (1.13; 4.47)]. Additionally, corneal thickness at the center, CCT [-61.19 (-73.79; -48.60)] and apex, pachy-apex [-41.86 (-72.64; -11.08)] were significantly thinner in keratoconic eyes compared to normal eyes. The pooled estimates for pachymetric progression index (PPI): PPImin [0.66 (0.43; 0.90)], PPImax [1.26 (0.87; 1.64)], PPIavg [0.90 (0.68; 1.12)], and Ambrosio relational thickness (ART): ARTmax [-242.77 (-288.86; -196.69)], and ARTavg [-251.08 (-308.76; -195.39)] revealed significantly more rapid pachymetric progression in keratoconic eyes than in normal eyes. The Pentacam Scheimpflug-derived keratometric, pachymetric, and pachymetric progression indices are good predictors in discriminating KC from normal eyes.
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Affiliation(s)
- Sandra Owusu
- Department of Optometry and Vision Science, University of Cape Coast, Cape Coast, Ghana
| | - Ebenezer Zaabaar
- Department of Optometry and Vision Science, University of Cape Coast, Cape Coast, Ghana
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong
| | - Michael Agyemang Kwarteng
- Department of Optometry, Bindura University of Science Education, Bindura, Zimbabwe
- Discipline of Optometry, University of Kwazulu-Natal, Durban, South Africa
| | - Samuel Ankamah
- University of Ghana Library System, University of Ghana, Accra, Ghana
| | | | - Samuel Kyei
- Department of Optometry and Vision Science, University of Cape Coast, Cape Coast, Ghana
- Biomedical and Clinical Research Center, University of Cape Coast, Cape Coast, Ghana
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Wan Q, Wei R, Ma K, Yin H, Deng YP, Tang J. Deep Learning-Based Automatic Diagnosis of Keratoconus with Corneal Endothelium Image. Ophthalmol Ther 2023; 12:3047-3065. [PMID: 37665500 PMCID: PMC10640564 DOI: 10.1007/s40123-023-00795-w] [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: 05/11/2023] [Accepted: 08/15/2023] [Indexed: 09/05/2023] Open
Abstract
INTRODUCTION The primary objective of this study was to develop an end-to-end model that can accurately identify corneal endothelial cells and diagnose keratoconus based on corneal endothelial images acquired from a non-contact specular microscope. METHODS This was a retrospective case-control study performed at the Refractive Surgery Center of West China Hospital. A total of 403 keratoconus eyes (221 patients) and 370 myopic eyes (185 normal controls) were consecutively recruited from January 2021 to September 2022. Specular microscopy was used to image and measure the morphometric parameters of the corneal endothelial cells. A Fully Convolutional Network model with a ResNet50 (FCN_ResNet50) was established to perform the endothelial segmentation. The images were then classified using an ensemble machine learning system consisting of four pre-trained deep learning networks: DenseNet121, ResNet50, Inception_v3, and MobileNet_v2. The performance of the models was evaluated based on different metrics, such as accuracy, intersection over union (IoU), and mean IoU. RESULTS We established a fully end-to-end deep-learning model for the segmentation of endothelial and diagnosis of keratoconus. For endothelial segmentation, the accuracy of the FCN_ResNet50 model achieved near 90% with mean IoU converging to about 80%. The ensemble machine learning system can achieve over 92% accuracy, and > 98% area under curve (AUC) values to diagnose keratoconus with endothelial cell images. In addition, we constructed a diagnostic model based on deep-learning features and developed an associated nomogram which manifested an excellent performance for diagnosis and monitoring the progression of keratoconus. CONCLUSIONS Our research developed an end-to-end model to automatically identify and assess corneal endothelial morphological changes in keratoconus eyes. Moreover, we also constructed a novel nomogram, which can provide valuable information for the diagnosis, monitoring, and management of the disease.
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Affiliation(s)
- Qi Wan
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Ran Wei
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Ke Ma
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Hongbo Yin
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Ying-Ping Deng
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, Sichuan, China.
| | - Jing Tang
- Department of Ophthalmology, West China Hospital, Sichuan University, Chengdu, Sichuan, China.
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Wallace HB, Vellara HR, Gokul A, McGhee CNJ, Meyer JJ. Comparison of Ectasia Detection in Early Keratoconus Using Scheimpflug-Based Corneal Tomography and Biomechanical Assessments. Cornea 2023; 42:1528-1535. [PMID: 36973879 DOI: 10.1097/ico.0000000000003273] [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: 09/10/2022] [Accepted: 01/15/2023] [Indexed: 03/29/2023]
Abstract
PURPOSE The aim of this study was to determine the detection of keratoconus using corneal biomechanical parameters only, a corneal tomographic parameter only, and a parameter that combines corneal biomechanical and tomographic indices. METHODS The discriminatory power of the Pentacam Random Forest Index (PRFI), Belin/Ambrósio Enhanced Ectasia Display (BAD-D) index, Corvis Biomechanical Index (CBI), and Tomographic and Biomechanical Index (TBI) to differentiate between normal eyes (n = 84), eyes with very asymmetric corneal ectasia (VAE-E, n = 21), and the fellow eyes without apparent ectasia based on normal tomography (VAE-NT, n = 21) was assessed. Statistical analyses were completed with R software using t -tests, Wilcoxon rank sum tests, and receiver operating characteristic (ROC) curves. The DeLong test was used to compare the area under the ROC curve (AUROC). RESULTS The TBI and PRFI had the highest AUROC when distinguishing between normal and VAE-E corneas (AUROC = 1.00, 95% CI = 1.00-1.00); however, they were not statistically superior to the CBI (AUROC = 0.97, P = 0.27) or BAD-D (AUROC = 1.00, P = 0.34). The TBI (AUROC = 0.92, 95% CI = 0.86-0.98) was superior to CBI (AUROC = 0.78, P = 0.02) and BAD-D (AUROC = 0.81, P = 0.02) when distinguishing between healthy and VAE-NT corneas. At a threshold of 0.72, the TBI had 99% sensitivity, 67% specificity, and 92% accuracy in distinguishing normal and VAE-NT corneas. CONCLUSIONS The TBI is a useful parameter for the screening of subclinical and frank keratoconus in tomographically normal eyes.
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Affiliation(s)
- Henry B Wallace
- Department of Ophthalmology, Faculty of Medical and Health Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand; and
| | - Hans R Vellara
- Department of Ophthalmology, Faculty of Medical and Health Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand; and
| | - Akilesh Gokul
- Department of Ophthalmology, Faculty of Medical and Health Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand; and
| | - Charles N J McGhee
- Department of Ophthalmology, Faculty of Medical and Health Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand; and
- Department of Ophthalmology, Auckland District Health Board, New Zealand
| | - Jay J Meyer
- Department of Ophthalmology, Faculty of Medical and Health Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand; and
- Department of Ophthalmology, Auckland District Health Board, New Zealand
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10
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Hashemi H, Asgari S, Mahmoud AM, Mehravaran S, Roberts CJ. Variability of CLMI-X parameters, zonal Kmax, and single-point Kmax in keratoconus progression. Eye (Lond) 2023; 37:3197-3202. [PMID: 36918626 PMCID: PMC10564939 DOI: 10.1038/s41433-023-02476-1] [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: 01/23/2022] [Revised: 01/31/2023] [Accepted: 02/27/2023] [Indexed: 03/16/2023] Open
Abstract
OBJECTIVES To compare the repeatability of Cone Location and Magnitude Index expanded (CLMI.X) parameters of 2 mm diameter zone of greatest corneal curvature (Cspot-Axi) and 1 mm diameter zone of thinnest pachmymetry (Spot-Pach) with the maximum single point keratometry (Kmax), 3 mm Zonal Kmax (Z-Kmax3), and thinnest single point pachymetry (TP) in keratoconus (KC). METHODS In this Comparative repeatability study, data from 36 eyes of 36 normal individuals and 72 eyes of 72 KC patients (28 eyes with ≤50.0D and 44 eyes with >50.0D Z-Kmax3) were analyzed. For each enrolled eye, imaging was done 6 times (3 consecutive acquisitions with a half hour break). For each parameter, the within-subject standard deviation (Sw) was calculated from the data of the six exams. RESULTS In the normal group, Cspot-Axi-Sw was different from Kmax-Sw (p = 0.0004). Also, Z-Kmax3-Sw was different from Kmax-Sw (p = 0.0297). The difference between Cspot-Axi-Sw and Z-Kmax3-Sw was statistically significant (p = 0.0482). In the KC group, Sw were significantly different between Cspot-Axi and Kmax (p < 0.0001), and between Z-Kmax3 and Kmax (p < 0.0001). In the Z-Kmax3 ≤ 50.0D subgroup, Sw were different between Cspot-Axi and Kmax (p = 0.0002). In the Z-Kmax3 > 50.0D subgroup, Sw were different between Cspot-Axi and Kmax (p < 0.0001), and between Z-Kmax3 and Kmax (p < 0.0001). Sw differences between Spot-Pach and TP were not significant in any of the study groups (all P > 0.05). CONCLUSIONS In the diagnosis and follow up of KC, the zonal averages of Cspot-Axi and Z-Kmax3 are more reliable than the single point Kmax. The repeatability of Spot-Pach is similar to TP and both variables should suit the purpose equally.
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Affiliation(s)
- Hassan Hashemi
- Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran.
| | - Soheila Asgari
- Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran
| | - Ashraf M Mahmoud
- Department of Ophthalmology & Visual Sciences, The Ohio State University, Wexner Medical Center, Columbus, OH, USA
| | - Shiva Mehravaran
- School of Computer, Mathematical, and Natural Sciences, Morgan State University, Baltimore, MD, USA
| | - Cynthia J Roberts
- Department of Ophthalmology & Visual Sciences, Department of Biomedical Engineering, The Ohio State University, Columbus, OH, USA
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11
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Aydemir GA, Kocabaş DO, Bilen A, Aydemir E, Bayat AH, Oren B, Kiziltoprak H. Evaluation of Retinal Layer Thicknesses in Patients with Keratoconus Using Retinal Layer Segmentation Analysis. Klin Monbl Augenheilkd 2023; 240:1199-1206. [PMID: 35320863 DOI: 10.1055/a-1743-3067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OBJECTIVE To conduct an evaluation of the effects of irregular astigmatism on the retinal nerve fiber layer (RNFL) and the retinal layers observed using spectral-domain optical coherence tomography (SD-OCT) in patients who had keratoconus (KC). MATERIALS AND METHODS A total of 255 eyes from 255 individuals, comprising 72 eyes of KC patients, 70 eyes of patients with astigmia, and 113 eyes of healthy controls were included in the analysis. RNFL scan maps (comprising global, temporal, superotemporal, inferotemporal, nasal, inferonasal, and superonasal maps) and macular thickness (MT) maps of a standard from the Early Treatment Diabetic Retinopathy Study (ETDRS) grid were assessed. The measurements were segmented automatically using Spectralis software, and included the RNFL, inner and outer plexiform layers (IPL, OPL), inner and outer nuclear layers (INL, ONL), ganglion cell layer, retinal pigment epithelium (RPE) in the central 6-mm ETDRS subfield. RESULTS The RNFL thickness in the KC group was lower when compared with the other two groups; however, statistically significant differences were noted in the global, temporal, superotemporal, and inferotemporal sectors (p < 0.05 for all). All of the central MT parameters showed significant variation among the groups, while a statistically significant decrease was noted in the KC group, except in the inferior outer sector (p = 0.741). In the segmentation analysis, the KC group had the significantly lowest IPL, ONL, RPE, and outer retinal layer (ORL) thickness among the groups (p < 0.05 for each). The astigmatic group was similar to the control group with regard to these parameters (p > 0.05 for each). CONCLUSION The eyes in the KC group appeared to have a thinner RNFL and MT when compared to those in the astigmatic and control groups. The ORLs, especially the ONL and RPE, were the most affected component of the macula in the KC group.
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Affiliation(s)
- Gozde Aksoy Aydemir
- Ophthalmology, Adiyaman Universitesi Egitim ve Arastirma Hastanesi, Adiyaman, Turkey
| | | | - Abdurrahman Bilen
- Ophthalmology, Adiyaman Universitesi Egitim ve Arastirma Hastanesi, Adiyaman, Turkey
| | - Emre Aydemir
- Ophthalmology, Adiyaman Universitesi Egitim ve Arastirma Hastanesi, Adiyaman, Turkey
| | - Alper Halil Bayat
- Ophyhalmology, Istanbul Medipol University, Birlik Mahallesi Bahçeler Caddesi No:5, Esenler/Istanbul, Turkey
| | - Burak Oren
- Ophthalmology, Adiyaman Universitesi Egitim ve Arastirma Hastanesi, Adiyaman, Turkey
| | - Hasan Kiziltoprak
- Ophthalmology, Adiyaman Universitesi Egitim ve Arastirma Hastanesi, Adiyaman, Turkey
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12
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Sideroudi H, Flockerzi E, Daas L, Jullien T, Xanthopoulou K, Hamon L, Seitz B. Baseline Characteristics of 1976 Patients With Ectatic Corneal Disorders at a Single Center From 2010 to 2021: A Cross-Sectional Study of the Homburg Keratoconus Center. Eye Contact Lens 2023; 49:392-398. [PMID: 37458424 DOI: 10.1097/icl.0000000000001014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2023] [Indexed: 08/26/2023]
Abstract
OBJECTIVES The study objective was to analyze the baseline characteristics of keratoconus (KC) patients at the Homburg Keratoconus Center from 2010 to 2021. METHODS This cross-sectional study included 3,674 eyes, with analysis of demographics, clinical findings, visual function, endothelial measurements, and topographic, tomographic, and corneal biomechanical data from the first visit. RESULTS Mean patient age was 36.3±13.8 years. The mean uncorrected distance visual acuity in log of minimal angle of resolution was 0.60 (20/80, Snellen equivalent), and the corrected mean was 0.3 (20/40). Of 1976 patients, 48.9% reported eye rubbing. Mean values (ranges) were 49.4±6.3 (36.3-78.0) D for steep keratometry, 462.4±66.0 (48.0-659.0) μm for thinnest corneal thickness, 9.7±8.7 (-0.5 to 88.8) for Belin/Ambrósio enhanced ectasia total deviation, 0.8±0.4 (0.0-1.0) for the Corvis biomechanical index, 0.9±0.2 (0.0-1.0) for the tomographic biomechanical index, 0.1±0.5 (-0.9 to 2.0) for the KC match index, 8.3±1.8 (2.2-17.7) mm Hg for corneal hysteresis, 7.1±2.2 (0.0-17.0) mm Hg for corneal resistance factor, and 2,562.9±326.3 (1,011-3,937) cells/mm2 for endothelial cell density. The average ABCDE KC stage was A2B3C1D1E2. Distance-corrected visual acuity correlated strongly with topometric, tomographic, and biomechanical data ( P <0.001). CONCLUSIONS This comprehensive description of baseline features of KC patients at a tertiary center provides a reference for further longitudinal and international multicentric studies.
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Affiliation(s)
- Haris Sideroudi
- Department of Ophthalmology, Saarland University Medical Center (UKS), Homburg/Saar, Germany
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13
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García de Oteyza G, Álvarez de Toledo J, Barraquer RI, Kling S. Localized Refractive Changes Induced by Symmetric and Progressive Asymmetric Intracorneal Ring Segments Assessed with a 3D Finite-Element Model. Bioengineering (Basel) 2023; 10:1014. [PMID: 37760115 PMCID: PMC10525444 DOI: 10.3390/bioengineering10091014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 08/21/2023] [Accepted: 08/23/2023] [Indexed: 09/29/2023] Open
Abstract
To build a representative 3D finite element model (FEM) for intracorneal ring segment (ICRS) implantation and to investigate localized optical changes induced by different ICRS geometries, a hyperelastic shell FEM was developed to compare the effect of symmetric and progressive asymmetric ICRS designs in a generic healthy and asymmetric keratoconic (KC) cornea. The resulting deformed geometry was assessed in terms of average curvature via a biconic fit, sagittal curvature (K), and optical aberrations via Zernike polynomials. The sagittal curvature map showed a locally restricted flattening interior to the ring (Kmax -11 to -25 dpt) and, in the KC cornea, an additional local steepening on the opposite half of the cornea (Kmax up to +1.9 dpt). Considering the optical aberrations present in the model of the KC cornea, the progressive ICRS corrected vertical coma (-3.42 vs. -3.13 µm); horizontal coma (-0.67 vs. 0.36 µm); and defocus (2.90 vs. 2.75 µm), oblique trefoil (-0.54 vs. -0.08 µm), and oblique secondary astigmatism (0.48 vs. -0.09 µm) aberrations stronger than the symmetric ICRS. Customized ICRS designs inspired by the underlying KC phenotype have the potential to achieve more tailored refractive corrections, particularly in asymmetric keratoconus patterns.
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Affiliation(s)
- Gonzalo García de Oteyza
- Clínica Oftalmológica García de Oteyza, 08017 Barcelona, Spain;
- Escuela de Doctorado, Universidad Autónoma de Barcelona (UAB), 08193 Barcelona, Spain
| | | | - Rafael I. Barraquer
- Centro de Oftalmología Barraquer, 08021 Barcelona, Spain
- Universitat Internacional de Catalunya (UIC), 08017 Barcelona, Spain
| | - Sabine Kling
- Institute for Biomedical Engineering, Department of Information Technology and Electrical Engineering, ETH Zurich, 8092 Zurich, Switzerland
- ARTORG Center for Biomedical Engineering Research, University of Bern, 3010 Bern, Switzerland
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14
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Sáez-Gutiérrez FL, Velázquez JS, Alió del Barrio JL, Alio JL, Cavas F. Novel Multivariable Evolutionary Algorithm-Based Method for Modal Reconstruction of the Corneal Surface from Sparse and Incomplete Point Clouds. Bioengineering (Basel) 2023; 10:989. [PMID: 37627874 PMCID: PMC10451391 DOI: 10.3390/bioengineering10080989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 08/16/2023] [Accepted: 08/17/2023] [Indexed: 08/27/2023] Open
Abstract
Three-dimensional reconstruction of the corneal surface provides a powerful tool for managing corneal diseases. This study proposes a novel method for reconstructing the corneal surface from elevation point clouds, using modal schemes capable of reproducing corneal shapes using surface polynomial functions. The multivariable polynomial fitting was performed using a non-dominated sorting multivariable genetic algorithm (NS-MVGA). Standard reconstruction methods using least-squares discrete fitting (LSQ) and sequential quadratic programming (SQP) were compared with the evolutionary algorithm-based approach. The study included 270 corneal surfaces of 135 eyes of 102 patients (ages 11-63) sorted in two groups: control (66 eyes of 33 patients) and keratoconus (KC) (69 eyes of 69 patients). Tomographic information (Sirius, Costruzione Strumenti Oftalmici, Italy) was processed using Matlab. The goodness of fit for each method was evaluated using mean squared error (MSE), measured at the same nodes where the elevation data were collected. Polynomial fitting based on NS-MVGA improves MSE values by 86% compared to LSQ-based methods in healthy patients. Moreover, this new method improves aberrated surface reconstruction by an average value of 56% if compared with LSQ-based methods in keratoconus patients. Finally, significant improvements were also found in morpho-geometric parameters, such as asphericity and corneal curvature radii.
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Affiliation(s)
- Francisco L. Sáez-Gutiérrez
- Department of Structures, Construction and Graphical Expression, Technical University of Cartagena, 30202 Cartagena, Spain; (F.L.S.-G.); (J.S.V.)
| | - Jose S. Velázquez
- Department of Structures, Construction and Graphical Expression, Technical University of Cartagena, 30202 Cartagena, Spain; (F.L.S.-G.); (J.S.V.)
| | - Jorge L. Alió del Barrio
- Division of Ophthalmology, Miguel Hernández University, 03690 Alicante, Spain; (J.L.A.d.B.); (J.L.A.)
- 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; (J.L.A.d.B.); (J.L.A.)
- Keratoconus Unit of Vissum Corporation Alicante, 03690 Alicante, Spain
- Department of Refractive Surgery, Vissum Corporation Alicante, 03690 Alicante, Spain
| | - Francisco Cavas
- Department of Structures, Construction and Graphical Expression, Technical University of Cartagena, 30202 Cartagena, Spain; (F.L.S.-G.); (J.S.V.)
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15
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Wagner FM, Sekundo W. Iatrogenic Keratectasia after Refractive Surgery - Causes, Prophylaxis, Therapy. Klin Monbl Augenheilkd 2023; 240:783-794. [PMID: 37348513 DOI: 10.1055/a-2073-8478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/24/2023]
Abstract
Iatrogenic keratectasia is induced thinning and protrusion of the cornea after laser refractive surgery. Known risk factors include an excessively thin postoperative residual stromal bed, a thicker flap, or preoperatively undetected evidence of preexisting subclinical keratoconus. The rate of post-refractive ectasia in eyes without identifiable preoperative risk factors is 20 per 100 000 eyes for photorefractive keratectomy, 90 per 100 000 eyes for laser in situ keratomileusis, and 11 per 100 000 eyes for small incision lenticule extraction. Traditional screening tools for preoperative risk include the ectasia risk score system and percentage of tissue alteration. More recent methods include corneal elastography and epithelial mapping, in addition to Artificial Intelligence methods for data analysis. Therapy includes contact lenses, cross-linking, implantation of intracorneal ring segments, penetrating or lamellar keratoplasty, and, in early studies, implantation of corneal lenticules.
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Affiliation(s)
- Felix Mathias Wagner
- Universitätsaugenklinik Mainz, Mainz, Deutschland
- Universitätsaugenklinik Marburg, Marburg, Deutschland
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16
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Momeni-Moghaddam H, Naroo SA. Keratoconus detection with a focus on new indices and techniques. Cont Lens Anterior Eye 2023; 46:101851. [PMID: 37183060 DOI: 10.1016/j.clae.2023.101851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Affiliation(s)
- Hamed Momeni-Moghaddam
- Rehabilitation Sciences Research Center, Zahedan University of Medical Sciences, Zahedan, Iran.
| | - Shehzad A Naroo
- College of Health and Life Sciences, Aston University, Birmingham, UK.
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17
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Bao F, Lopes BT, Zheng X, Ji Y, Wang J, Elsheikh A. Corneal Biomechanics Losses Caused by Refractive Surgery. Curr Eye Res 2023; 48:137-143. [PMID: 36001080 DOI: 10.1080/02713683.2022.2103569] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Recent advances, specifically in the understanding of the biomechanical properties of the cornea and its response to diseases and surgical interventions, have significantly improved the safety and surgical outcomes of corneal refractive surgery, whose popularity and demand continue to grow worldwide. However, iatrogenic keratectasia resulting from the deterioration in corneal biomechanics caused by surgical interventions, although rare, remains a global concern. On one hand, in vivo biomechanical evaluation, enabled by clinical imaging systems such as the ORA and the Corvis ST, has significantly improved the risk profiling of patients for iatrogenic keratectasia. That is despite the fact the biomechanical metrics provided by these systems are considered indicators of the cornea's overall stiffness rather than its intrinsic material properties. On the other hand, new surgical modalities including SMILE were introduced to offer superior biomechanical performance to LASIK, but this superiority could not be proven clinically, creating more myths than answers. The literature also includes sound evidence that tPRK provided the highest preservation of corneal biomechanics when compared to both LASIK and SMILE. The aim of this review is twofold; to discuss the importance of corneal biomechanical evaluation prior to refractive surgery, and to assess the current understanding of cornea's biomechanical deterioration caused by mainstream corneal refractive surgeries. The review has led to an observation that new imaging techniques, parameters and evaluation systems may be needed to reflect the true advantages of specific refractive techniques and when these advantages are significant enough to offer better protection against post-surgery complications.
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Affiliation(s)
- FangJun Bao
- Eye Hospital, Wenzhou Medical University, Wenzhou, China.,The Institute of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, China
| | - Bernardo T Lopes
- School of Engineering, University of Liverpool, Liverpool, UK.,Department of Ophthalmology, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil
| | - XiaoBo Zheng
- Eye Hospital, Wenzhou Medical University, Wenzhou, China.,The Institute of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, China
| | - YuXin Ji
- Eye Hospital, Wenzhou Medical University, Wenzhou, China
| | - JunJie Wang
- Eye Hospital, Wenzhou Medical University, Wenzhou, China.,The Institute of Ocular Biomechanics, Wenzhou Medical University, Wenzhou, China
| | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool, UK.,Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing, China.,National Institute for Health Research (NIHR) Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, London, UK
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18
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Sideroudi H, Flockerzi E, Seitz B. Differential Diagnosis of Keratoconus Based on New Technologies. Klin Monbl Augenheilkd 2023; 240:57-72. [PMID: 35940178 DOI: 10.1055/a-1920-6929] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Keratoconus (KC) must be distinguished from other corneal ectatic diseases and thinning disorders for stage-appropriate and suitable management of each condition. The most relevant corneal pathologies that may imitate the tomographic KC pattern are pellucid marginal degeneration (PMD), keratoglobus, posterior keratoconus, and Fuchs-Terrien marginal degeneration (FTMD). In moderate cases of KC, differentiation is typically possible using slit lamp examination and corneal tomography with evaluation of the location of the corneal thinning region. In early cases, however, differential diagnosis may be more challenging since the cornea may look relatively normal. In severe cases, the extended area of corneal thinning also complicates differentiation. Biomicroscopic findings cannot always give all the information needed to distinguish KC from related ectatic corneal conditions. The aim of this work is to discuss contemporary techniques and findings to assist physicians to identify the correct diagnosis. Corneal topography has been used in recent decades as the main tool for imaging in ectatic corneal diseases. Moreover, Scheimpflug cameras (corneal tomographers), which analyze both anterior and posterior corneal surfaces, curvatures, pachymetry, elevation data, higher order aberrations, Fourier analysis of keratometric data, and corneal density have become the most promising tools for diagnosis and follow-up of ectatic diseases. A noninvasive air pulse tonometer in conjunction with an ultrahigh-speed Scheimpflug camera complements tomographic findings by analyzing biomechanical corneal properties. Α confocal microscopy system, which is a novel clinical technique for the study of corneal cellular structure, could contribute effectively in the same direction. Moreover, anterior segment optical coherence tomography (AS-OCT) creates cross-sections, which can be generated into a three-dimensional structure to produce corneal epithelial thickness (ET) measurements. ET mapping is increasingly recognized as a sensitive tool for the diagnosis of ocular surface disorders. Combining information of all these systems could lead to a more effective identification and differential diagnosis of ectatic corneal disorders.
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Affiliation(s)
- Haris Sideroudi
- Department of Ophthalmology, Saarland University Medical Center and Saarland University Faculty of Medicine, Homburg/Saar, Germany
| | - Elias Flockerzi
- Department of Ophthalmology, Saarland University Medical Center and Saarland University Faculty of Medicine, Homburg/Saar, Germany
| | - Berthold Seitz
- Department of Ophthalmology, Saarland University Medical Center and Saarland University Faculty of Medicine, Homburg/Saar, Germany
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19
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Ji Y, Liu S, Hong X, Lu Y, Wu X, Li K, Li K, Liu Y. Advances in artificial intelligence applications for ocular surface diseases diagnosis. Front Cell Dev Biol 2022; 10:1107689. [PMID: 36605721 PMCID: PMC9808405 DOI: 10.3389/fcell.2022.1107689] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Accepted: 12/05/2022] [Indexed: 01/07/2023] Open
Abstract
In recent years, with the rapid development of computer technology, continual optimization of various learning algorithms and architectures, and establishment of numerous large databases, artificial intelligence (AI) has been unprecedentedly developed and applied in the field of ophthalmology. In the past, ophthalmological AI research mainly focused on posterior segment diseases, such as diabetic retinopathy, retinopathy of prematurity, age-related macular degeneration, retinal vein occlusion, and glaucoma optic neuropathy. Meanwhile, an increasing number of studies have employed AI to diagnose ocular surface diseases. In this review, we summarize the research progress of AI in the diagnosis of several ocular surface diseases, namely keratitis, keratoconus, dry eye, and pterygium. We discuss the limitations and challenges of AI in the diagnosis of ocular surface diseases, as well as prospects for the future.
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Affiliation(s)
- Yuke Ji
- The Laboratory of Artificial Intelligence and Bigdata in Ophthalmology, Affiliated Eye Hospital of Nanjing Medical University, Nanjing, China
| | - Sha Liu
- The Laboratory of Artificial Intelligence and Bigdata in Ophthalmology, Affiliated Eye Hospital of Nanjing Medical University, Nanjing, China
| | - Xiangqian Hong
- Shenzhen Eye Hospital, Jinan University, Shenzhen, China
| | - Yi Lu
- Shenzhen Eye Hospital, Jinan University, Shenzhen, China
| | - Xingyang Wu
- Shenzhen Eye Hospital, Jinan University, Shenzhen, China
| | - Kunke Li
- Shenzhen Eye Hospital, Jinan University, Shenzhen, China,*Correspondence: Yunfang Liu, ; Keran Li, ; Kunke Li,
| | - Keran Li
- The Laboratory of Artificial Intelligence and Bigdata in Ophthalmology, Affiliated Eye Hospital of Nanjing Medical University, Nanjing, China,*Correspondence: Yunfang Liu, ; Keran Li, ; Kunke Li,
| | - Yunfang Liu
- Department of Ophthalmology, First Affiliated Hospital of Huzhou University, Huzhou, China,*Correspondence: Yunfang Liu, ; Keran Li, ; Kunke Li,
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20
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Harbiyeli II, Gul Olke K, Erdem E, Yagmur M. Correction of moderate to high refractive astigmatism with extended range toric soft contact lenses in patients with different patterns of astigmatism. Ophthalmic Physiol Opt 2022; 42:807-813. [PMID: 35333414 DOI: 10.1111/opo.12980] [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: 08/20/2021] [Revised: 02/20/2022] [Accepted: 02/21/2022] [Indexed: 11/29/2022]
Abstract
PURPOSE This study aimed to evaluate the visual performance of extended range, toric soft contact lenses (TSCLs) in patients with keratoconus and moderate to high astigmatism with different astigmatic patterns. METHODS This was a retrospective, cross-sectional clinical study. Extended range TSCL users with astigmatism ≥3.0 D were included. Cases were categorised into three subgroups, namely regular, irregular (non-keratoconus) and keratoconic based on the topographic pattern of astigmatism. In addition, subjects were subdivided based on the degree of astigmatism. RESULTS Fifty five patients (82 eyes) were enrolled, of whom 28 (51%) were female. The mean age was 24.2 ± 7.5 (range: 8-41 years) years. Thirty-six eyes with regular astigmatism (43.9%), 34 eyes with irregular astigmatism (41.5%) and 12 eyes with keratoconus (14.6%) were included. The percentage improvement in visual acuity (VA) was significantly higher with contact lenses compared with spectacles in all groups (p < 0.001), with the highest improvement in subjects with keratoconus (p = 0.03). Twenty six (31.7%), 30 (36.6%) and 26 eyes (31.7%) had moderate (-3.0 to -4.24 D), moderate/high (-4.25 to -5.99 D) and high (≤-6.0 D) astigmatism, respectively. The percentage improvement in VA with contact lenses was statistically significantly higher than for spectacle wear in all groups (p < 0.001). CONCLUSIONS This study demonstrated that satisfactory visual outcomes can be obtained with extended range TSCLs in patients having moderate to high astigmatism with different astigmatic patterns.
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Affiliation(s)
| | - Kubra Gul Olke
- Department of Ophthalmology, Seyhan State Hospital, Adana, Turkey
| | - Elif Erdem
- Department of Ophthalmology, Faculty of Medicine, Cukurova University, Adana, Turkey
| | - Meltem Yagmur
- Department of Ophthalmology, Faculty of Medicine, Cukurova University, Adana, Turkey
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21
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Braga Vieira S, Rivadeneira-Bueno D, Ortiz-Toquero S, Martin R. Optometric practices and attitudes in keratoconus patient management in Latin America. Clin Exp Optom 2022; 106:386-394. [PMID: 35298892 DOI: 10.1080/08164622.2022.2048997] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
CLINICAL RELEVANCE To explore optometric practices and attitudes in the management of keratoconus patients in LatinAmerica and how they are influenced by eye-care technology will help to minimise disease progression and their impact on patients' quality of life in Latin America. BACKGROUND Keratoconus is a progressive, bilateral and asymmetric corneal disorder that requires a multidisciplinary approach, the use of different eye assessment technology, and different management approaches; mainly contact lenses and surgery. METHODS Self-reported answers to an online survey (adapted to primary eye care) distributed via a newsletter emailed by various professional organisations across 15 Latin American countries were assessed and compared with those previously reported in three European countries. RESULTS Answers from 977 eye care practitioners (60%) with >10 years of experience (396 in Latin America and 581 in Europe) were assessed. A total of 65.9% of Latin American responders prescribed rigid corneal lenses (RCL), although more than half of the respondents (54.0%) would fit more RCL if they underwent further training in RCL fitting. A majority of Latin American practitioners (74.0%) considered that RCL fitting is more difficult in keratoconus, requiring more diagnostic lenses (4.6 ± 2.7; median 4; range 1-10) than are necessary for healthy eyes. Low availability of corneal topography was reported in Latin America (23%), although practitioners with topographers are more likely to prescribe RCL (92.3%) and detect more new patients with keratoconus per year (83.5%). A minority of respondents referred keratoconus patients to another optometrist (25.8%) or (40.4%) participated in comanagement with ophthalmologists. CONCLUSION This study provides initial evidence regarding keratoconus management in Latin America and suggests that actions are necessary to improve RCL training, facilitate eye-care technology accessibility and encourage comanagement between eye care practitioners to minimise disease progression and their impact on patients' quality of life in Latin America.
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Affiliation(s)
- Sabrina Braga Vieira
- Optometry Research Group, IOBA Eye Institute. School of Optometry, University of Valladolid, Valladolid, Spain.,Department Optometry, University of Contestado (UnC), Canoinhas (Brazil)
| | - Doris Rivadeneira-Bueno
- Department of Physic (Optics and Contact Lenses), Universidad Nacional del Sur, Bahía Blanca, Argentina
| | - Sara Ortiz-Toquero
- Optometry Research Group, IOBA Eye Institute. School of Optometry, University of Valladolid, Valladolid, Spain
| | - Raul Martin
- Optometry Research Group, IOBA Eye Institute. School of Optometry, University of Valladolid, Valladolid, Spain
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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: 7] [Impact Index Per Article: 3.5] [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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Abdolalizadeh P, Ghiasian L, Hadavandkhani A, Eshaghi A, Hadi Y, Nadjafi-Semnani F. Comparing pentacam HR screening indices in different normal corneal thicknesses among refractive surgery candidates. J Curr Ophthalmol 2022; 34:200-207. [PMID: 36147272 PMCID: PMC9487003 DOI: 10.4103/joco.joco_249_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 10/30/2021] [Accepted: 10/31/2021] [Indexed: 11/10/2022] Open
Abstract
Purpose: To compare Pentacam indices in normal eyes with different corneal thicknesses. Methods: It is a retrospective observational study. Ninety-six normal eyes of 96 patients who were referred for refractive surgery in a tertiary university-based hospital from October 2015 to April 2019 were recruited consecutively. Corneal keratometry as well as Pentacam's software Belin-Ambrósio Enhanced Ectasia Display (BAD) parameters including pachymetry progression indices (PPIs), maximum Ambrosio's relational thickness (ART-max), corneal elevations, normalized deviations, BAD total deviation value (BAD-D), and anterior surface indices were measured by Pentacam HR (Type 70900). The included were classified as thin (26 eyes), average (45 eyes), and thick (25 eyes) corneas with the thinnest point thickness of ≤496 μm, 497–595 μm, and ≥596 μm, respectively. The specificities of all parameters were calculated based on routine cut-off values. Results: The refraction, keratometry, and elevations were not different (P > 0.05). All PPIs (minimum, average, and maximum) of thick corneas were significantly lower than average and thin corneas (P < 0.001). ART-max increased by thickening of the cornea (P < 0.001). BAD-D score and normalized indices of pachymetric parameters decreased with the increase of thickness (P < 0.001), while specificities of all indices increased with corneal thickening. More than 96% of thick corneas were classified as normal PPI-max (24/25), ART-max (25/25), and BAD-D (25/25), while nearly <54% of thin corneas (14/26 for PPI-max, 9/26 for ART-max, and 12/26 for BAD-D) were normal. Conclusions: The pachymetry-related indices and BAD-D were different among normal corneas with various thicknesses. The specificities of PPIs, ART-max, and BAD-D of thin corneas were lower than in thick corneas.
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Hashemi H, Heirani M, Ambrósio R, Hafezi F, Naroo SA, Khorrami-Nejad M. The link between Keratoconus and posterior segment parameters: An updated, comprehensive review. Ocul Surf 2021; 23:116-122. [PMID: 34890805 DOI: 10.1016/j.jtos.2021.12.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 11/26/2021] [Accepted: 12/06/2021] [Indexed: 02/07/2023]
Abstract
Keratoconus (KCN) has been typically known as a disorder with effects limited to the cornea. Because of this viewpoint, less attention has been devoted to its effects on the posterior segment structures. We aimed to provide a comprehensive review of the literature to understand the potential link between KCN and posterior segment structures and their functions. It is clear from the extensive evidence in the literature that KCN can be associated with morphological and functional changes in different parts of the posterior segment. It is worth noting that anatomical changes have been not only noted in several layers of the retina but also in the optic nerve head and the choroid. Several mechanisms have been proposed to explain this observation, including incidents induced by oxidative stress in keratoconic corneas and retinal adaptions to the distorted image that lands on the retina. Consequently, when KCN has been diagnosed, it seems practical to consider assessing the retinal and choroidal profile using optical coherence tomography and potentially functional abnormalities through electrophysiology procedures.
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Affiliation(s)
- Hassan Hashemi
- Noor Ophthalmology Research Center, Noor Eye Hospital, Tehran, Iran
| | - Mohsen Heirani
- Translational Ophthalmology Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran.
| | - Renato Ambrósio
- Department of Ophthalmology, Federal University of the State of Rio de Janeiro, Brazil
| | - Farhad Hafezi
- ELZA Institute, Dietikon, Zurich, Switzerland; Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Shehzad A Naroo
- College of Health and Life Sciences, Aston University, Birmingham, B4 7ET, UK
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Khorrami-Nejad M, Heirani M. Letter to the Editor Re: "The Relationship Between Keratoconus Stage and the Thickness of the Retinal Layers". Turk J Ophthalmol 2021; 51:334-335. [PMID: 34702890 PMCID: PMC8558690 DOI: 10.4274/tjo.galenos.2021.58259] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Affiliation(s)
- Masoud Khorrami-Nejad
- Translational Ophthalmology Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohsen Heirani
- Translational Ophthalmology Research Center, Farabi Eye Hospital, Tehran University of Medical Sciences, Tehran, Iran
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26
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Kammoun H, Piñero DP, Álvarez de Toledo J, Barraquer RI, García de Oteyza G. Clinical Outcomes of Femtosecond Laser-Assisted Implantation of Asymmetric ICRS in Keratoconus With No Coincidence of Topographic and Comatic Axes. J Refract Surg 2021; 37:693-699. [PMID: 34661475 DOI: 10.3928/1081597x-20210712-04] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To analyze the clinical outcomes obtained with asymmetric intracorneal corneal ring segments (ICRS) of variable thickness and width in patients with keratoconus, identifying predictive parameters of the final visual outcome. METHODS This prospective, longitudinal, non-comparative clinical trial enrolled 35 eyes of 27 patients with keratoconus with a significant difference among corneal topographic and comatic axes. All eyes underwent implantation of AJL-pro+ ICRS (AJL Ophthalmic). Visual, refractive, corneal topographic and aberrometric, and pachymetric changes were evaluated during a 3-month follow-up. RESULTS Significant changes were detected at 3 months after surgery in manifest sphere and cylinder, spherical equivalent, overall blur strength, and corrected distance visual acuity (CDVA) (P < .001). No losses of two or more lines of CDVA were observed, whereas 94.3% (33) of eyes gained one or more lines of CDVA. Keratometric readings and the magnitude of anterior corneal astigmatism were significantly reduced with surgery (P < .001), as well as the levels of corneal coma (P < .001) and spherical aberration (P = .007). Likewise, a significant change toward less prolateness was observed (P < .001). Significant correlations were found among the change in CDVA and preoperative CDVA (r = -0.532, P = .001), and between the change in primary coma root mean square and the preoperative level of spherical aberration (r = -0.542, P = .001) and coma root mean square (r = -0.719, P < .001). CONCLUSIONS The implantation of the ICRS evaluated in keratoconus with no coincidence between topographic and comatic axes regularizes the corneal shape and reduces the level of higher order aberrations, inducing a significant visual improvement. [J Refract Surg. 2021;37(10):693-699.].
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Cao K, Verspoor K, Chan E, Daniell M, Sahebjada S, Baird PN. Machine learning with a reduced dimensionality representation of comprehensive Pentacam tomography parameters to identify subclinical keratoconus. Comput Biol Med 2021; 138:104884. [PMID: 34607273 DOI: 10.1016/j.compbiomed.2021.104884] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 09/15/2021] [Accepted: 09/19/2021] [Indexed: 12/26/2022]
Abstract
PURPOSE To investigate the performance of a machine learning model based on a reduced dimensionality parameter space derived from complete Pentacam parameters to identify subclinical keratoconus (KC). METHODS All 1692 available parameters were obtained from the Pentacam imaging machine on 145 subclinical KC and 122 control eyes. We applied a principal component analysis (PCA) to the complete Pentacam dataset to reduce its parameter dimensionality. Subsequently, we investigated machine learning performance of the random forest algorithm with increasing numbers of components to identify their optimal number for detecting subclinical KC from control eyes. RESULTS The dimensionality of the complete set of 1692 Pentacam parameters was reduced to 267 principal components using PCA. Subsequent selection of 15 of these principal components explained over 85% of the variance of the original Pentacam-derived parameters and input to train a random forest machine learning model to achieve the best accuracy of 98% in detecting subclinical KC eyes. The model established also reached a high sensitivity of 97% in identification of subclinical KC and a specificity of 98% in recognizing control eyes. CONCLUSIONS A random forest-based model trained using a modest number of components derived from a reduced dimensionality representation of complete Pentacam system parameters allowed for high accuracy of subclinical KC identification.
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Affiliation(s)
- Ke Cao
- Centre for Eye Research Australia, Melbourne, Victoria, Australia; Department of Surgery, Ophthalmology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Karin Verspoor
- School of Computing Technologies, RMIT University, Melbourne, Australia; School of Computing and Information Systems, The University of Melbourne, Melbourne, Australia
| | - Elsie Chan
- Centre for Eye Research Australia, Melbourne, Victoria, Australia; Department of Surgery, Ophthalmology, The University of Melbourne, Melbourne, Victoria, Australia; Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - Mark Daniell
- Centre for Eye Research Australia, Melbourne, Victoria, Australia; Department of Surgery, Ophthalmology, The University of Melbourne, Melbourne, Victoria, Australia; Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia
| | - Srujana Sahebjada
- Centre for Eye Research Australia, Melbourne, Victoria, Australia; Department of Surgery, Ophthalmology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Paul N Baird
- Department of Surgery, Ophthalmology, The University of Melbourne, Melbourne, Victoria, Australia.
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28
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Fernández J, Peris-Martínez C, Pérez-Rueda A, Hamida Abdelkader SM, Roig-Revert MJ, Piñero DP. Evaluation of a new nomogram for Ferrara ring segment implantation in keratoconus. Int J Ophthalmol 2021; 14:1371-1383. [PMID: 34540613 DOI: 10.18240/ijo.2021.09.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Accepted: 02/25/2021] [Indexed: 11/23/2022] Open
Abstract
AIM To evaluate the short-term clinical outcomes of Ferrara rings in keratoconus using an optimized nomogram developed after several years of research and retrospective analysis of clinical data. METHODS This prospective longitudinal non-comparative clinical trial evaluated 88 eyes of 88 patients (age 18-62y) with keratoconus diagnosis from two Spanish centers. Ferrara ring segment (AJL Ophthalmic) implantation was performed in all cases, using the mechanical procedure in 25 eyes (28.4%) and a femtosecond laser-assisted procedure in 63 eyes (71.6%). The ring segments implanted in each case were selected using a new optimized nomogram that considered variables such as anterior corneal asphericity and astigmatism or the discrepancy among astigmatism and coma orientations. Visual, refractive, corneal topographic, aberrometric, and pachymetric changes after surgery were evaluated during a 3-month follow-up. RESULTS The implants induced a significant refractive change as well as an improvement in uncorrected (UDVA) and corrected distance visual acuity (CDVA; P<0.001). Postoperative CDVA of 0.10 logMAR or better was achieved in 28.4% and 46.5% of eyes, respectively. Two eyes (2.3%) lost two or more lines of CDVA whereas a total of 53.5% of eyes gained lines of CDVA. A significant central anterior and posterior corneal flattening was induced (P≤0.003), with a significant reduction of anterior (P<0.001) and posterior corneal astigmatisms (P=0.048), and a change in anterior asphericity (P<0.001). Total primary coma (6 mm pupil) change was also statistically significant (preoperative 3.66±3.04 µm vs postoperative 2.33±2.26 µm, P<0.001). No significant differences were found in the effect of ring segments between cases implanted using the mechanical and femtosecond techniques (P≥0.101). CONCLUSION The implantation of Ferrara rings based on the nomogram evaluated is safe and effective for promoting a visual rehabilitation in keratoconus, with a relevant control of primary coma aberration.
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Affiliation(s)
- Joaquín Fernández
- Department of Ophthalmology (Qvision), Vithas Virgen del Mar Hospital, Almería 04120, Spain.,Department of Ophthalmology, Torrecárdenas Hospital Complex, Almería 04009, Spain
| | - Cristina Peris-Martínez
- Cornea and External Diseases Unit, FISABIO-Oftalmología Médica (FOM), Valencia 46015, Spain.,Aviño Peris Eye Clinic, Valencia 46001, Spain.,Department of Surgery, Ophthalmology, University of Valencia, Valencia 46010, Spain
| | - Antonio Pérez-Rueda
- Department of Ophthalmology, Torrecárdenas Hospital Complex, Almería 04009, Spain
| | | | - María José Roig-Revert
- Cornea and External Diseases Unit, FISABIO-Oftalmología Médica (FOM), Valencia 46015, Spain.,Department of Surgery, Ophthalmology, University of Valencia, Valencia 46010, Spain
| | - David P Piñero
- Department of Optics, Pharmacology, and Anatomy, University of Alicante, Alicante 03690, Spain
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Effect of upper eyelid blepharoplasty on corneal biomechanical, topographic and tomographic parameters 4 weeks after surgery. Int Ophthalmol 2021; 42:113-121. [PMID: 34478004 PMCID: PMC8803703 DOI: 10.1007/s10792-021-02006-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 08/07/2021] [Indexed: 11/11/2022]
Abstract
Purpose To investigate the effect of “skin-only” upper eyelid blepharoplasty on corneal biomechanics and central as well as peripheral topographic/tomographic parameters before and 4 weeks after surgery. Methods In a prospective study, the corneal hysteresis (CH) and corneal resistance factor (CRF) were evaluated before and after blepharoplasty. Corneal topographic (maximum simulated keratometry value, inferior-superior value, index of surface variance, index of vertical asymmetry, index of height asymmetry, index of height decentration) and tomographic parameters (corneal thickness, corneal astigmatism and mean 5-mm- and 7-mm-zone keratometry value) were measured by the Pentacam HR. Statistical analysis was performed using a linear mixed model considering correlated data of both eyes. Results This study included 42 eyes of 35 patients (mean age: 64.5 years, range 52–82 years). Four weeks after surgery CH and CRF increased (9.4 ± 2.3 to 10.2 ± 2.2 mmHg and 9.7 ± 2.1 to 10.5 ± 2.2 mmHg) but did not reach statistical significance (P = 0.100 and P = 0.072). A significant increase in central maximum simulated keratometry value (Kmax) from 45.0 ± 2.3 to 45.4 ± 2.2 diopters (D) was observed (P = 0.004). Inferior-superior value (I-S) and index of surface variance (ISV) showed significant changes from 0.32 ± 0.98 to 0.10 ± 0.98 D (P = 0.02) and from 19.98 ± 9.84 to 22.93 ± 11.23 (P = 0.009), respectively. These alterations did not affect the subjective spherical equivalent (-0.09 ± 4.71 to -0.04 ± 4.51 D; P = 0.437) and the best-corrected distance visual acuity of patients (0.11 ± 0.14 to 0.15 ± 0.15 logMAR; P = 0.142). Age, gender and corneal thickness were not correlated with pre and postoperative differences of CH, CRF, corneal compensated IOP, Kmax, corneal astigmatism or I-S. Conclusion The trend of increasing CH and CRF values might indicate a rise of corneal damping capacity. Despite statistically significant differences of Kmax, I-S and ISV, all other tomographical and topographical parameters did not change 4 weeks after surgery. The corneal steepening with a mean change of 0.4 diopters and the decrease of I-S with a mean of 0.22 diopters do not seem to have a clinically relevant effect for blepharoplasty patients in daily practice.
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Clinical evaluation of the effectiveness of asymmetric intracorneal ring with variable thickness and width for the management of keratoconus. J Cataract Refract Surg 2021; 47:722-730. [PMID: 33278234 DOI: 10.1097/j.jcrs.0000000000000525] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 11/07/2020] [Indexed: 11/25/2022]
Abstract
PURPOSE To evaluate the short-term clinical outcomes obtained with a new model of asymmetric intracorneal ring segments (ICRS) with variable thickness and base width in keratoconus. SETTING Four ophthalmologic centers in Spain. DESIGN Prospective multicenter longitudinal noncomparative clinical trial. METHODS Thirty-one keratoconus eyes of 25 patients (aged 15 to 50 years) that underwent implantation of ICRS of variable thickness and base (AJL-pro+) in 4 Spanish centers were enrolled. Visual, refractive, topographic, aberrometric, and pachymetric changes were evaluated during a 3-month follow-up. Complications were also recorded. RESULTS Statistically significant changes after surgery were observed in uncorrected distance visual acuity (P = .002) and corrected distance visual acuity (CDVA) (P = .005), as well as in spherical equivalent (P = .006). At 3 months postoperatively, no loss of 2 or more lines of CDVA was observed, whereas 48.4% (15) of eyes gained ≥1 line. Statistically significant changes were observed in the steepest and mean keratometric values (P ≤ .047) and in the magnitude of astigmatism (P < .001) of both anterior and posterior corneal surfaces. Likewise, a change to a less prolate shape of the anterior surface was found (P = .011). Primary coma was also reduced significantly at 1 month postoperatively (P = .001, mean reduction 40.1%). No serious implant-related complications occurred during the follow-up. CONCLUSIONS The implantation of intrastromal asymmetric ring segments of variable thickness and base width in keratoconus corneas induces a significant anterior corneal flattening, leading to refractive changes, a significant reduction of its prolate shape and irregularity, and improvement in patient CDVA.
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Gim Y, Jun RM, Han KE. Agreement between Scheimpflug Camera and the Swept-source Optical Coherence Tomography Measurements in Keratometry and Higher-order Aberrations. KOREAN JOURNAL OF OPHTHALMOLOGY 2021; 35:337-348. [PMID: 34237207 PMCID: PMC8521334 DOI: 10.3341/kjo.2021.0076] [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: 05/14/2021] [Accepted: 06/30/2021] [Indexed: 11/23/2022] Open
Abstract
PURPOSE To evaluate the compatibility of corneal curvature and astigmatism, and higher-order aberrations (HOAs) measured by the Scheimpflug camera Pentacam HR and the swept-source optical coherence tomography ANTERION. METHODS This prospective study included normal subjects with no ophthalmic history. Steep keratometry (K), flat K, astigmatism and its axis of the anterior and posterior surfaces, total corneal power, and HOAs using the two instruments were compared. To compare the mean values of the measurements, a paired t-test was used. Bland-Altman analysis was applied to assess the agreement between the two devices. RESULTS Fifty-three eyes of 53 subjects were evaluated. There were statistically significant differences for steep K, astigmatism, and vector J0, J45 in the anterior surface and total corneal power between the two devices (p < 0.05). There were also significant differences in the most of the keratometric values of the posterior corneal surface (p < 0.05) except J0 (p = 0.410). Both devices showed strong positive correlations in steep K, flat K, astigmatism (r > 0.81, p < 0.001) with wide ranges of a 95% limit of agreement. Vectoral components were significantly correlated (r > 0.78, p < 0.001) with narrow 95% limit of agreement, except J45 of the posterior surface (r = 0.39, p = 0.004). In the corneal HOAs, there were statistically significant differences in the vertical coma, horizontal trefoil, spherical aberration, and root mean square of each fifth- and sixth-order Zernike coefficient (p = 0.043, p = 0.041, p < 0.001, p < 0.001, and p < 0.001, respectively). Other HOAs showed moderate to strong positive correlations (r > 0.37, p < 0.05). Most HOAs, except for the horizontal trefoil, showed clinically acceptable agreements. The total root mean square of HOAs was not significantly different between the two devices (p = 0.122). CONCLUSIONS Most of the keratometric values cannot be used interchangeably. However, the vectoral component of astigmatism showed clinically good agreement. Several HOAs have statistically significant differences; however, almost all HOAs showed acceptable agreements, except for the horizontal trefoil.
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Affiliation(s)
- Yujin Gim
- Institute of Ophthalmology and Optometry, Department of Ophthalmology, Ewha Womans University Mokdong Hospital, Ewha Womans University College of Medicine, Seoul, Korea
| | - Roo Min Jun
- Institute of Ophthalmology and Optometry, Department of Ophthalmology, Ewha Womans University Seoul Hospital, Ewha Womans University College of Medicine, Seoul, Korea
| | - Kyung Eun Han
- Institute of Ophthalmology and Optometry, Department of Ophthalmology, Ewha Womans University Mokdong Hospital, Ewha Womans University College of Medicine, Seoul, Korea
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Abdelmotaal H, Abdou AA, Omar AF, El-Sebaity DM, Abdelazeem K. Pix2pix Conditional Generative Adversarial Networks for Scheimpflug Camera Color-Coded Corneal Tomography Image Generation. Transl Vis Sci Technol 2021; 10:21. [PMID: 34132759 PMCID: PMC8242686 DOI: 10.1167/tvst.10.7.21] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Purpose To assess the ability of pix2pix conditional generative adversarial network (pix2pix cGAN) to create plausible synthesized Scheimpflug camera color-coded corneal tomography images based upon a modest-sized original dataset to be used for image augmentation during training a deep convolutional neural network (DCNN) for classification of keratoconus and normal corneal images. Methods Original images of 1778 eyes of 923 nonconsecutive patients with or without keratoconus were retrospectively analyzed. Images were labeled and preprocessed for use in training the proposed pix2pix cGAN. The best quality synthesized images were selected based on the Fréchet inception distance score, and their quality was studied by calculating the mean square error, structural similarity index, and the peak signal-to-noise ratio. We used original, traditionally augmented original and synthesized images to train a DCNN for image classification and compared classification performance metrics. Results The pix2pix cGAN synthesized images showed plausible subjectively and objectively assessed quality. Training the DCNN with a combination of real and synthesized images allowed better classification performance compared with training using original images only or with traditional augmentation. Conclusions Using the pix2pix cGAN to synthesize corneal tomography images can overcome issues related to small datasets and class imbalance when training computer-aided diagnostic models. Translational Relevance Pix2pix cGAN can provide an unlimited supply of plausible synthetic Scheimpflug camera color-coded corneal tomography images at levels useful for experimental and clinical applications.
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Affiliation(s)
- Hazem Abdelmotaal
- Department of Ophthalmology, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Ahmed A Abdou
- Department of Ophthalmology, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Ahmed F Omar
- Department of Ophthalmology, Faculty of Medicine, Assiut University, Assiut, Egypt
| | | | - Khaled Abdelazeem
- Department of Ophthalmology, Faculty of Medicine, Assiut University, Assiut, Egypt
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Özsaygılı C, Yıldırım Y. The Relationship Between Keratoconus Stage and the Thickness of the Retinal Layers. Turk J Ophthalmol 2021; 51:75-82. [PMID: 33951894 PMCID: PMC8109033 DOI: 10.4274/tjo.galenos.2020.84748] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Objectives To examine the relationship between keratoconus (KC) stage and the thickness of the retinal layers. Materials and Methods Retinal layer thicknesses were compared between 85 eyes of 85 KC patients and 40 eyes of 40 controls similar in age, sex, and axial length. KC patients were staged as stage 1, 2, or 3 according to the Amsler-Krumeich staging system, and segmentation of the retinal layers was performed with spectral domain optical coherence tomography automatic segmentation program. The thickness of the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), and retinal pigment epithelium (RPE) in the central 1 mm Early Treatment Diabetic Retinopathy Study subfield was analyzed. Results There was no significant difference between the control and KC groups in the segmentation of the RNFL, GCL, IPL, or OPL (p=0.306; p=0.661; p=0.893, p=0.664, respectively). The INL differed significantly between control and stage 2 KC, control and stage 3 KC, stage 1 and 2 KC, and stage 2 and 3 KC, increasing in thickness with higher stage (p=0.004; p=0.005: p=0.001; p=0.002, respectively). The RPE also differed significantly between control and stage 2 KC, control and stage 3 KC, stage 1 and 2 KC, and stage 2 and 3 KC, showing decreased thickness with higher stage (p=0.03; p=0.001; p=0.001; p<0.001, respectively). The ONL also thinned as stage increased, but the results were not statistically significant (p=0.051). Conclusion More advanced KC stage was associated with increased thickness of the INL layer, where the neuroglial cell bodies are located, and decreased thickness in the outer retinal layers, especially the RPE.
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Affiliation(s)
- Cemal Özsaygılı
- Kayseri City Hospital, Clinic of Ophthalmology, Kayseri, Turkey
| | - Yener Yıldırım
- Kayseri City Hospital, Clinic of Ophthalmology, Kayseri, Turkey
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Moscovici BK, Rodrigues PF, Rodrigues RAM, Rios LC, Simoncelli R, Freitas MMS, Torquetti L. Evaluation of keratoconus progression and visual improvement after intrastromal corneal ring segments implantation: A retrospective study. Eur J Ophthalmol 2021; 31:3483-3489. [PMID: 33719637 DOI: 10.1177/11206721211000646] [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: 02/06/2023]
Abstract
OBJECTIVE To investigate the role of ICRS in halting keratoconus progression in a large sample of patients. METHODS A retrospective, non-comparative, interventional study based on the review of medical records of patients diagnosed with keratoconus who underwent Ferrara corneal ring segment implantation. A retrospective chart analysis study of 123 operated eyes with follow-up ranging from 3 to 16 years (mean 5.3 ± 3.6 years) was performed. This study was carried out at Ocular Surgery Unit, São Paulo, Brazil. All topographic data were obtained from Pentacam (Oculus, Arlington, USA). The same surgeon performed all surgeries, and the Ferrara ICRS nomogram was used for ICRS selection in all cases. RESULTS Corrected distance visual acuity, keratometry, and topographic astigmatism improved in most cases, with statistical significance. In 42 eyes (53.8%), there was an increase in K1 or K2, and in 36 (46.2%), there was a reduction or maintenance in K1. Considering a difference higher than 1 D, between 3-month post-surgery and final visit (group 3), 32 eyes (41%) showed an increase, and 46 eyes (59%) ended equal or below this value. CONCLUSION The implantation of ICRS showed improvement in visual and keratometric indexes. The majority of patients did not increase more than one diopter in keratometric values after ICRS implantation. ICRS may be effective for slowing disease progression, especially in older patients.
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Ortiz-Toquero S, Rodriguez G, Martin R. Clinical guidelines for the management of keratoconus patients with gas permeable contact lenses based on expert consensus and available evidence. Curr Opin Ophthalmol 2021; 32:S1-S11. [PMID: 33332882 DOI: 10.1097/icu.0000000000000728] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW Fitting rigid gas permeable contact lenses (RGP CLs) in keratoconic patients is the most common visual rehabilitation option to improve patients' quality of life, but require long patient and practitioner chair time. The purpose of this review is to provide evidence-based clinical practice guidelines (CPG) in the management of patients with keratoconus with RGP CLs. RECENT FINDINGS An extensive literature review from 1990 to 2017 identified 354 potentially relevant publications. Fifty-two articles were reviewed and included in the CPG. An international expert panel of eight contact lens practitioners, with vast experience in keratoconus management reviewed and appraised the CPG following the Appraisal of Guidelines for Research and Evaluation II consortium requirements. The developed CPG clearly outlines a strategy for the successful fitting of RGP CLs in patients with keratoconus. This includes how to calculate parameters of the first diagnostic lens, criteria for assessing good fit and a standardized schedule of wear time and follow-up appointments. SUMMARY The current evidence and consensus-based CPG helps guide clinicians in a successful strategy for fitting RGP CLs in patients with keratoconus.
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Affiliation(s)
- Sara Ortiz-Toquero
- School of Optometry, Department of Physic TAO, University of Valladolid, Valladolid
- Instituto Universitario de Oftalmobiología Aplicada (IOBA Eye Institute), University of Valladolid, Valladolid
- Optometry Research Group, IOBA Eye Institute, University of Valladolid, Valladolid
- Department of Ophthalmology, Hospital Universitario Ramón y Cajal, Madrid, Spain
| | - Guadalupe Rodriguez
- School of Optometry, Department of Physic TAO, University of Valladolid, Valladolid
- Instituto Universitario de Oftalmobiología Aplicada (IOBA Eye Institute), University of Valladolid, Valladolid
- Optometry Research Group, IOBA Eye Institute, University of Valladolid, Valladolid
| | - Raul Martin
- School of Optometry, Department of Physic TAO, University of Valladolid, Valladolid
- Instituto Universitario de Oftalmobiología Aplicada (IOBA Eye Institute), University of Valladolid, Valladolid
- Optometry Research Group, IOBA Eye Institute, University of Valladolid, Valladolid
- Faculty of Health and Human Sciences, Plymouth University, Plymouth, UK
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Larco P, Larco P, Torres D, Piñero DP. Intracorneal Ring Segment Implantation for the Management of Keratoconus in Children. Vision (Basel) 2020; 5:1. [PMID: 33374847 PMCID: PMC7838879 DOI: 10.3390/vision5010001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 12/10/2020] [Accepted: 12/22/2020] [Indexed: 11/17/2022] Open
Abstract
The short-term safety and efficacy of intracorneal ring segment (ICRS) implantation in keratoconus eyes of children are investigated in this study. A retrospective interventional case series study including a total of 33 keratoconus eyes (age 8 to 17 years) that had undergone ICRS (Keraring segments, Mediphacos) implantation was conducted. Information about visual, refractive, pachymetric, corneal topographic and aberrometric, and corneal endothelial changes during a 3-month follow-up were extracted and analysed. A significant improvement was observed in logMAR corrected distance visual acuity (p = 0.005), combined with a statistically significant reduction in keratometric readings (p < 0.001). A reduction in the magnitude of corneal astigmatism of ≥1 D was observed in 52.8% of eyes. No significant changes were observed in corneal endothelial density (p = 0.317). Significant changes were found in the anterior vertical coma component (p = 0.002) as well as in the spherical aberration of the posterior corneal surface (p = 0.004). Only two relevant complications were described: one corneal microperforation with penetration of the ring segment into the anterior chamber (1 eye, 2.8%), and a case of ring extrusion (1 eye, 2.8%). ICRS implantation in children keratoconus eyes allows a reduction of corneal astigmatism, irregularity, and aberrations, leading to a significant visual improvement.
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Affiliation(s)
- Pablo Larco
- Clínica Larco Visión, Quito 170135, Ecuador; (P.L.); (P.L.J.); (D.T.)
| | - Pablo Larco
- Clínica Larco Visión, Quito 170135, Ecuador; (P.L.); (P.L.J.); (D.T.)
| | - Daniel Torres
- Clínica Larco Visión, Quito 170135, Ecuador; (P.L.); (P.L.J.); (D.T.)
| | - David P. Piñero
- Department of Optics, Pharmacology and Anatomy, University of Alicante, 03690 Alicante, Spain
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Abdelmotaal H, Mostafa MM, Mostafa ANR, Mohamed AA, Abdelazeem K. Classification of Color-Coded Scheimpflug Camera Corneal Tomography Images Using Deep Learning. Transl Vis Sci Technol 2020; 9:30. [PMID: 33384884 PMCID: PMC7757611 DOI: 10.1167/tvst.9.13.30] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 11/05/2020] [Indexed: 12/26/2022] Open
Abstract
Purpose To assess the use of deep learning for high-performance image classification of color-coded corneal maps obtained using a Scheimpflug camera. Methods We used a domain-specific convolutional neural network (CNN) to implement deep learning. CNN performance was assessed using standard metrics and detailed error analyses, including network activation maps. Results The CNN classified four map-selectable display images with average accuracies of 0.983 and 0.958 for the training and test sets, respectively. Network activation maps revealed that the model was heavily influenced by clinically relevant spatial regions. Conclusions Deep learning using color-coded Scheimpflug images achieved high diagnostic performance with regard to discriminating keratoconus, subclinical keratoconus, and normal corneal images at levels that may be useful in clinical practice when screening refractive surgery candidates. Translational Relevance Deep learning can assist human graders in keratoconus detection in Scheimpflug camera color-coded corneal tomography maps.
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Affiliation(s)
- Hazem Abdelmotaal
- Department of Ophthalmology, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Magdi M Mostafa
- Department of Ophthalmology, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Ali N R Mostafa
- Department of Ophthalmology, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Abdelsalam A Mohamed
- Department of Ophthalmology, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Khaled Abdelazeem
- Department of Ophthalmology, Faculty of Medicine, Assiut University, Assiut, Egypt
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Armstrong BK, Smith SD, Romac Coc I, Agarwal P, Mustapha N, Navon S. Screening for Keratoconus in a High-Risk Adolescent Population. Ophthalmic Epidemiol 2020; 28:191-197. [PMID: 32822269 DOI: 10.1080/09286586.2020.1804593] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE To estimate the prevalence of keratoconus (KC) in a majority-Emirati adolescent population and to demonstrate the feasibility of screening using a dual Scheimpflug and Placido imaging device. METHODS Adolescent subjects from two secondary schools in Abu Dhabi, UAE underwent corneal imaging with the Galilei tomographer (Ziemer Ophthalmic Systems AG, Port, Switzerland). The prevalence of KC and KC suspects was determined using a combination of both subjective and objective criteria. Objective criteria included these KC indices: percent probability of keratoconus, inferior-superior index, asphericity asymmetry index, maximum keratometry and thinnest pachymetry. Subjective pattern analysis was performed by four experienced cornea specialists. Subjects were classified by each cornea specialist into three groups: normal, KC and KC suspect. The final classification was made by group reconciliation of cases where disagreement was present. Inter-observer agreement was assessed with the kappa statistic. RESULTS A total of 839 eyes of 420 students between 10 and 19 years of age underwent corneal tomography. After the exclusion of 251 eyes due to insufficient scan quality based on internal instrument-derived standards, 588 eyes of 339 subjects were included in the analysis. The prevalence of KC and KC suspect was estimated to be 2.7% (95% CI [1.2%, 5.0%]) and 19.8% (95% CI [15.7%, 24.4%]), respectively. There was a strong inter-observer agreement between examiners' classification of the subjects' KC status (kappa = 0.84). CONCLUSION KC is highly prevalent in Emirati adolescents. Screening secondary school students for keratoconus appears to be feasible and may be indicated in this population to improve early detection and intervention.
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Affiliation(s)
- Brian K Armstrong
- Eye Institute, Cleveland Clinic Abu Dhabi, Abu Dhabi, UAE.,Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Scott D Smith
- Eye Institute, Cleveland Clinic Abu Dhabi, Abu Dhabi, UAE.,Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Ivana Romac Coc
- Eye Institute, Cleveland Clinic Abu Dhabi, Abu Dhabi, UAE.,Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Prateek Agarwal
- Eye Institute, Cleveland Clinic Abu Dhabi, Abu Dhabi, UAE.,Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Najah Mustapha
- School Health Department, Abu Dhabi Health Services Company (SEHA), Abu Dhabi, UAE
| | - Samuel Navon
- Eye Institute, Cleveland Clinic Abu Dhabi, Abu Dhabi, UAE.,Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, USA
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Alvarez ER, Montesinos GM, Torres Piedra DM, Palacios NT, Téllez OF. Corneal Indices Determined with Pentacam in Possible Candidates for Corneal Refractive Surgery. Open Ophthalmol J 2020. [DOI: 10.2174/1874364102014010039] [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
Objective:
To describe the level of correlation of clinical refractive variables with corneal indices in Pentacam Scheimpflug tomography, demonstrate the usefulness of the study of corneal indices in the diagnosis of keratoconus (KC), and identify the corneal indexes with the greatest influence on the diagnosis of KC.
Methods:
A descriptive, retrospective, and cross-sectional study was conducted in 69 patients (138 eyes) with refractive disorders, possible candidates for corneal refractive surgery, at the Exilaser Ophthalmological Center, Cuenca, Ecuador, from March to August 2019. Corneal indices were studied using Pentacam. Statistical correlation methods, Levene’s test, Fisher’s exact test, Cramérs’ V coefficient, and multiple correspondence analyses were used.
Results:
The variables refractive cylinder and central keratometry had a direct correlation with the corneal indices (p<0.001). An inverse correlation was obtained between central pachymetry and corneal indices (p<0.001). A high level of dependence on central KC index (CKI) (Cramér V = 0.785) and KC index (KI) (Cramér V = 0.775) was obtained with the diagnosis of KC.
Conclusion:
Pentacam is a valuable tool in the analysis of corneal indices for the diagnosis of KC, given its high level of correlation with clinical refractive variables. The selection of candidates for refractive surgery, even when there is no diagnosis of KC, is strengthened with the analysis of the corneal indices. The indices with the most intense level of dependence with the diagnosis of KC are, in order, the following indices: CKI, KI, vertical asymmetry, minimum radius, and variation of the surface.
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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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Fard AM, Patel SP, Sorkhabi RD, Salekzamani S, Pezzino E, Nader ND. Posterior pole retinal thickness distribution pattern in keratoconus. Int Ophthalmol 2020; 40:2807-2816. [PMID: 32556673 DOI: 10.1007/s10792-020-01464-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Accepted: 06/02/2020] [Indexed: 10/24/2022]
Abstract
PURPOSE To evaluate the pattern of retinal thickness distribution in patients with keratoconus (KCN) and its correlation with disease severity. METHODS For this cross-sectional cohort study, the study subjects with documented keratoconus and normal eyes were prospectively enrolled. All subjects had anterior segment (Pentacam HR) and posterior segment (Spectralis) imaging. Posterior segment imaging by optical coherence tomography included the posterior pole asymmetry analysis map. Data were analyzed with multiple linear regression models and correlation tests to examine the mean and variance of the measured thickness of the retina and its distribution relative to the presence and severity of KCN. RESULTS A total of 24 subjects with keratoconus (48 eyes) and 14 normal subjects (28 eyes) enrolled in this study. The posterior pole retinal thickness, both superior and inferior hemifields, as well as the overall retinal thickness in KCN patients was greater than the control group. There was a direct correlation between the overall retinal thickness of the posterior pole and the severity of KCN (R2 = 0.422, P < 0.001). However, the variability of the retinal thickness showed no difference between KCN-afflicted and healthy eyes. CONCLUSION Although KCN is a disease of the anterior segment of the eye, we found an orderly increase in posterior pole retinal thickness that is correlated with the severity of disease in KCN eyes compared to control. These findings suggest that the retina may maintain some degree of plasticity to respond to the degraded optical system of the eye.
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Affiliation(s)
- Ali Mahdavi Fard
- Department of Ophthalmology, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY, USA
| | - Sangita P Patel
- Department of Ophthalmology, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY, USA.,Research and Ophthalmology Services, Veterans Administration of Western New York Healthcare System, Buffalo, NY, USA
| | - Raana Daei Sorkhabi
- Department of Ophthalmology, Tabriz university of Medical Sciences, Tabriz, Iran
| | - Sara Salekzamani
- Department of Ophthalmology, Tabriz university of Medical Sciences, Tabriz, Iran
| | - Elena Pezzino
- Department of Anesthesiology, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, UB-Gateway Bldg Suite 550, 77 Goodell Street, Buffalo, NY, 14203, USA
| | - Nader D Nader
- Department of Anesthesiology, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, UB-Gateway Bldg Suite 550, 77 Goodell Street, Buffalo, NY, 14203, USA.
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Cao K, Verspoor K, Sahebjada S, Baird PN. Evaluating the Performance of Various Machine Learning Algorithms to Detect Subclinical Keratoconus. Transl Vis Sci Technol 2020; 9:24. [PMID: 32818085 PMCID: PMC7396174 DOI: 10.1167/tvst.9.2.24] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Accepted: 02/05/2020] [Indexed: 12/26/2022] Open
Abstract
Purpose Keratoconus (KC) represents one of the leading causes of corneal transplantation worldwide. Detecting subclinical KC would lead to better management to avoid the need for corneal grafts, but the condition is clinically challenging to diagnose. We wished to compare eight commonly used machine learning algorithms using a range of parameter combinations by applying them to our KC dataset and build models to better differentiate subclinical KC from non-KC eyes. Methods Oculus Pentacam was used to obtain corneal parameters on 49 subclinical KC and 39 control eyes, along with clinical and demographic parameters. Eight machine learning methods were applied to build models to differentiate subclinical KC from control eyes. Dominant algorithms were trained with all combinations of the considered parameters to select important parameter combinations. The performance of each model was evaluated and compared. Results Using a total of eleven parameters, random forest, support vector machine and k-nearest neighbors had better performance in detecting subclinical KC. The highest area under the curve of 0.97 for detecting subclinical KC was achieved using five parameters by the random forest method. The highest sensitivity (0.94) and specificity (0.90) were obtained by the support vector machine and the k-nearest neighbor model, respectively. Conclusions This study showed machine learning algorithms can be applied to identify subclinical KC using a minimal parameter set that are routinely collected during clinical eye examination. Translational Relevance Machine learning algorithms can be built using routinely collected clinical parameters that will assist in the objective detection of subclinical KC.
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Affiliation(s)
- Ke Cao
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.,Department of Surgery, Ophthalmology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Karin Verspoor
- Department of Computing and Information Systems, The University of Melbourne, Melbourne, Victoria, Australia
| | - Srujana Sahebjada
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia.,Department of Surgery, Ophthalmology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Paul N Baird
- Department of Surgery, Ophthalmology, The University of Melbourne, Melbourne, Victoria, Australia
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Classification of Keratoconus Based on Anterior Corneal High-order Aberrations: A Cross-validation Study. Optom Vis Sci 2020; 97:169-177. [PMID: 32168239 DOI: 10.1097/opx.0000000000001489] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
SIGNIFICANCE Placido disc-based videokeratography is one of the most extensively used methods for corneal topographic assessments in keratoconus. Anterior corneal wavefront analysis has been demonstrated to be an effective tool to manage keratoconus eyes. However, currently, there is no clinically adequate classification system for keratoconus. PURPOSE The aim of this study was to analyze the usefulness of anterior corneal high-order aberrations in keratoconus classification provided by Placido disc-based videokeratography conducting a cross-validation analysis. METHODS Corneal topography of 70 normal and 77 keratoconic eyes (divided according to the Amsler-Krumeich classification [n = 21, stage 1; n = 30, stage 2; and n = 26, stage 3]) was assessed using Placido disc-based videokeratography (Oculus Keratograph [Oculus Optikgeräte GmbH, Wetzlar, Germany]). Receiver operating characteristic curve analysis was used to compare the mean values of coma, trefoil, tetrafoil, secondary astigmatism, spherical aberration, and coma-like, third-, and fourth-order root mean square (RMS) to calculate cutoff values, sensitivity, and specificity to discriminate between normal and stage 1 keratoconus eyes and between each keratoconus stage after cross-validation analysis. RESULTS All wavefront aberrations were significantly different between the normal and keratoconus groups (P ≤ .01). The coma and third-order RMS values (cutoff values, 0.367 and 0.359 μm, respectively) provide better sensitivity (99 and 100%, respectively) and specificity (100%) to discriminate keratoconus (stage 1) from healthy eyes compared with trefoil, tetrafoil, secondary astigmatism, spherical aberration, and coma-like and fourth-order RMS values (sensitivity >84% and specificity >57%). The coma and third-order RMS values showed the highest specificity (100%) and great sensitivity (90 and 87%, respectively) to differentiate between stages 1 and 2 and good sensitivity (97 and 100%) and specificity (81 and 88%) to differentiate between stages 2 and 3. CONCLUSIONS Anterior corneal high-order aberrations, specifically coma and third-order RMS, could be useful in keratoconus diagnosis and topographical classification. These new cutoff values could improve different stages of keratoconus eyes discrimination.
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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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Bardan AS, Kubrak-Kisza M, Kisza KJ, Nanavaty MA. Impact of classifying keratoconus location based on keratometry or pachymetry on progression parameters. Clin Exp Optom 2019; 103:312-319. [PMID: 31184397 DOI: 10.1111/cxo.12927] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 03/25/2019] [Accepted: 04/24/2019] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND This study sought to assess the impact of classifying keratoconus location based on thinnest pachymetry or maximum keratometry (Kmax) on progression parameters after corneal crosslinking (CXL). METHODS In this observational study, patients were followed up at one, three, six and 12 months after CXL. All patients underwent visual acuity, Scheimpflug tomography and slitlamp assessment at all follow-ups. Keratoconus was classified as central, paracentral and peripheral based on X and Y co-ordinates of either thinnest pachymetry (Group 1) or Kmax (Group 2). Progression parameters Kmax, ABCD grading, anterior, posterior and total wavefront (WF) aberrations were compared between the groups. RESULTS Fifty-two eyes (43 patients) were classified into Groups 1 and 2: there were 82.8 per cent, 13.4 per cent, 3.8 per cent and 42.3 per cent, 38.4 per cent, 19.2 per cent central, paracentral and peripheral cones respectively. Central cones: Group 1: 'C' decreased after three months, Kmax, 'A', anterior and total WF decreased after six months. Group 2: Kmax, anterior and total WF decreased after three months, 'A' decreased at 12 months, whereas 'C' increased from three months. Paracentral cones: Group 1: no significant changes. Group 2: Kmax and 'A' decreased after six months, 'C' increased after three months. Peripheral cones: Group 1: no significant changes. Group 2: 'C' increased only at one month. CONCLUSION Thinnest pachymetry and Kmax should not be used interchangeably when categorising keratoconus. Although keratoconus may have thin cornea centrally, the Kmax may not be central. For the majority of parameters considered for monitoring progression, changes were noticed earlier when the keratoconus was classified based on Kmax.
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Affiliation(s)
- Ahmed S Bardan
- Sussex Eye Hospital, Brighton & Sussex University Hospitals NHS Trust, Brighton, UK.,Brighton & Sussex Medical School, University of Sussex, Brighton, UK.,Faculty of Medicine, Alexandria University, Alexandria, Egypt
| | | | - Krystian J Kisza
- Sussex Eye Hospital, Brighton & Sussex University Hospitals NHS Trust, Brighton, UK
| | - Mayank A Nanavaty
- Sussex Eye Hospital, Brighton & Sussex University Hospitals NHS Trust, Brighton, UK.,Brighton & Sussex Medical School, University of Sussex, Brighton, UK
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Issarti I, Consejo A, Jiménez-García M, Hershko S, Koppen C, Rozema JJ. Computer aided diagnosis for suspect keratoconus detection. Comput Biol Med 2019; 109:33-42. [DOI: 10.1016/j.compbiomed.2019.04.024] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 04/11/2019] [Accepted: 04/20/2019] [Indexed: 01/03/2023]
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Peris-Martínez C, Dualde-Beltrán C, Fernández-López E, Roig-Revert MJ, Hernández-Díaz M, Piñero DP. Effect of the variability in implantation depth of intracorneal ring segments using the femtosecond laser technology in corneal ectasia. Eur J Ophthalmol 2019; 30:668-675. [DOI: 10.1177/1120672119852026] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Purpose: To analyze the impact of the depth of implantation of intracorneal ring segments on morphological, biomechanical, and clinical outcomes in ectatic corneas. Methods: This prospective longitudinal study enrolled 40 eyes of 29 patients (age 20–51 years) with corneal ectasia that underwent intracorneal ring segments implantation (KeraRing, Mediphacos). Changes in visual acuity, refraction, corneal tomography, and corneal biomechanics (Ocular Response Analyzer, Reichert) were evaluated during a 6 month follow-up. Likewise, changes in ring segment implantation depth measured by optical coherence tomography (Visante OCT, Carl Zeiss Meditec) were also evaluated. Results: Mean relative depth of implantation was 71.6 ± 5.8%, 71.5 ± 6.5%, and 71.9 ± 6.3% at 1, 3, and 6 months after surgery, respectively (p = 0.827). The difference between the real relative depth of implantation and the theoretical attempted value of 70% was not statistically significant (p = 0.072). Differences in spherical equivalent during the follow-up changed significantly depending on the level of relative depth of implantation (p = 0.036), with an increase of 0.114 D per each 1% increase in relative depth of implantation. Likewise, a decrease of –0.194 D in the steepest keratometric reading was found per each decrease of 1% in relative depth of implantation (p = 0.026). Changes in corneal thickness (p = 0.092) and biomechanics (p = 0.080) were not related to relative depth of implantation. Conclusion: The effect on visual acuity and refraction of intracorneal ring segments when implanted in corneal ectasia is less clinically relevant when the implantation is done at a very deep plane. The variability of the depth of intracorneal ring segments implantation when using femtosecond laser technology is minimal and with no clinically significant effect on clinical outcomes.
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Affiliation(s)
- Cristina Peris-Martínez
- Cornea and External Diseases Unit, FISABIO-Oftalmología Médica (FOM), Valencia, Spain
- Clínica Oftalmológica Aviñó&Peris, Valencia, Spain
| | | | - Ester Fernández-López
- Cornea and External Diseases Unit, FISABIO-Oftalmología Médica (FOM), Valencia, Spain
| | | | - Mikhail Hernández-Díaz
- Cornea and External Diseases Unit, FISABIO-Oftalmología Médica (FOM), Valencia, Spain
- Clínica Oftalmológica Aviñó&Peris, Valencia, Spain
| | - David P Piñero
- Department of Optics, Pharmacology and Anatomy, University of Alicante, Alicante, Spain
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Whether Keratectasia Area Shown in Corneal Topography Is Appropriate for Evaluating the Effect of Corneal Cross-Linking for Keratoconus: A 12-Month Follow-Up Study. BIOMED RESEARCH INTERNATIONAL 2019; 2019:1762537. [PMID: 31073520 PMCID: PMC6470445 DOI: 10.1155/2019/1762537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 02/03/2019] [Accepted: 03/20/2019] [Indexed: 11/24/2022]
Abstract
Purpose To analyze the keratectasia area (KEA) shown in corneal topography before and after corneal cross-linking (CXL) in patients with progressive keratoconus (KC) and figure out whether KEA is appropriate for evaluating the effect of CXL. Methods A retrospective analysis was conducted in 34 eyes from 24 progressive KC patients who have underwent CXL from 2015 to 2017. Area with K-value more than 47D shown in the corneal topography was marked and identified as KEA. Keratometry (K1, K2, and Kmax), KEA, thinnest corneal thickness (TCT), and endothelial cell density (ECD) were evaluated preoperatively or at months 3, 6, and 12 postoperatively. The changes of KEA before and after operation were evaluated. The relation of KEA and other parameters, including Kmax and TCT, was analyzed. Results Linear regression model revealed the KEA, Kmax, K1, and K2 decreased after CXL in model y = 0.9622 -0.02408 x (P<0.05), y = 0.9982 -0.003469 x(P<0.05), y = 0.9977 + -0.001347 x(P<0.05), y = 0.9992 + -0.001779 x(P<0.05) (y represents KEA, Kmax, K1, or K2; x represents time (month)). The KEA is significantly decreased in early stage (before month 3) (P<0.05); however, the Kmax, K1, and K2 have no significant decrease in early stage (P= 0.09, 0.19, 0.32). Conclusions The KEA is more sensitive than K-value in describing the morphological changes of cornea after CXL, especially in early stage after treatment.
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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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Garcia-Ferrer FJ, Akpek EK, Amescua G, Farid M, Lin A, Rhee MK, Varu DM, Musch DC, Mah FS, Dunn SP. Corneal Ectasia Preferred Practice Pattern®. Ophthalmology 2019; 126:P170-P215. [DOI: 10.1016/j.ophtha.2018.10.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 10/09/2018] [Indexed: 02/07/2023] Open
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