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Vandevenne MM, Berendschot TT, Visser N, Dickman MM, Nuijts RM. Late-onset corneal edema after customized crosslinking for progressive keratoconus. Am J Ophthalmol Case Rep 2024; 35:102090. [PMID: 38983453 PMCID: PMC11231532 DOI: 10.1016/j.ajoc.2024.102090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 03/11/2024] [Accepted: 06/01/2024] [Indexed: 07/11/2024] Open
Abstract
Purpose We describe a patient after customized crosslinking (CXL) for progressive keratoconus who developed corneal edema with spontaneous resolution. Observations A 24-year-old male with progressive keratoconus of the left eye underwent a customized CXL procedure with a total energy of 10 J/cm2 for 16.4 minutes. Preoperative corrected distance visual acuity (CDVA) was 20/30 with a maximum keratometry (K)-value of 58.6 diopter (D) and the thinnest point measured 414 μm. The preoperative endothelial cell density (ECD) was 2414 cells/mm2. During treatment, corneal thickness was 325 μm after epithelial debridement and 375 μm after the application of 0.1 % riboflavin containing HPMC. After the treatment, antibiotic and steroid drops were prescribed for 5 days and 3 weeks, respectively. At the 1-month post-CXL visit the patient had no complaints, visual acuity and clinical examination showed no irregularities. At the 4-months post-CXL visit the patient complained of blurry vision. The CDVA was 20/100 and slit-lamp examination showed microcystic corneal edema. The corneal thickness at the thinnest point measured 440 μm. One month later the edema had resolved spontaneously and CDVA had restored to 20/25. Corneal thickness at the thinnest point measured 415 μm, the ECD was 1514 cells/mm2 and confocal microscopy showed normal structural changes in the anterior stroma after CXL, with the demarcation line located at a depth of 414 μm, just above the corneal endothelium. Conclusions and importance We report a case of corneal edema following customized CXL with endothelial cell loss that resolved spontaneously. We recommend either adhering to a minimal stromal thickness of 400 μm before administering UV-A irradiation, using a contact lens or adjusting the irradiation to prevent this complication.
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Affiliation(s)
- Magali M.S. Vandevenne
- Maastricht University Medical Centre+ University Clinic of Ophthalmology, the Netherlands, P.O. box 5800, 6202 AZ Maastricht, the Netherlands
| | - Tos T.J.M. Berendschot
- Maastricht University Medical Centre+ University Clinic of Ophthalmology, the Netherlands, P.O. box 5800, 6202 AZ Maastricht, the Netherlands
| | - Nienke Visser
- Maastricht University Medical Centre+ University Clinic of Ophthalmology, the Netherlands, P.O. box 5800, 6202 AZ Maastricht, the Netherlands
| | - Mor M. Dickman
- Maastricht University Medical Centre+ University Clinic of Ophthalmology, the Netherlands, P.O. box 5800, 6202 AZ Maastricht, the Netherlands
| | - Rudy M.M.A. Nuijts
- Maastricht University Medical Centre+ University Clinic of Ophthalmology, the Netherlands, P.O. box 5800, 6202 AZ Maastricht, the Netherlands
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Qureshi M, Watson SL, Kandel H. Pulsed corneal crosslinking in the treatment of Keratoconus: a systematic review and meta-analysis. Graefes Arch Clin Exp Ophthalmol 2024:10.1007/s00417-024-06622-7. [PMID: 39215849 DOI: 10.1007/s00417-024-06622-7] [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: 01/25/2024] [Revised: 07/29/2024] [Accepted: 08/15/2024] [Indexed: 09/04/2024] Open
Abstract
PURPOSE Corneal crosslinking (CXL) procedures are the treatment of choice in halting progressive corneal ectasia and preserving visual acuity due to keratoconus. Pulsed crosslinking (P-CXL) was developed using intermittent pulsing ultraviolet (UV) light to mitigate the depletion of oxygen levels that occurs with continuous UV exposure in standard crosslinking protocols (C-CXL). This study aimed to explore the use of P-CXL in the treatment of keratoconus and determine whether the availability of oxygen in P-CXL carries superior efficacy outcomes as an alternative to C-CXL modalities. METHODS This review was undertaken in accordance with PRISMA guidelines. A search of several databases conducted with two separate reviewers resulted in 29 papers meeting inclusion criteria for the review, 14 selected for meta-analysis. Primary outcomes assessed by the included papers included maximum keratometry (Kmax), corrected and uncorrected distance visual acuity (CDVA, UDVA), and secondary outcomes included central corneal thickness (CCT), endothelial cell count and demarcation line. Statistical analyses were carried out on Review Manager 5.4 and the meta-analysis employed a random-effects model, which estimated the weighted effect size of raw means using inverse variance weights. RESULTS At 12 months P-CXL showed statistically significant reductions in Kmax (-0.75 D; p < 0.001) and improvement in CDVA (-0.10 logMAR; p < 0.001) compared to baseline. The meta-analysis of comparative studies determined that mean differences in Kmax, CDVA, UDVA, Kmean and CCT after 12 months were not statistically significant between pulsed and continuous crosslinking groups. CONCLUSIONS Overall, P-CXL is effective in improving visual acuity and keratometry outcomes in keratoconus. The meta-analysis did not show a statistically significant difference in Kmax and CDVA between P-CXL and C-CXL, indicating a non-inferiority of P-CXL. However, findings of the meta-analysis are limited by the fact that different energy levels and exposure times were used for P-CXL in comparison to C-CXL in some studies, making it unsuitable to determine whether the efficacy of CXL is improved by the use of pulsed light. KEY MESSAGES What is Known • Pulsed crosslinking (P-CXL) uses intermittent UV light to prevent oxygen depletion when using higher energy protocols, unlike continuous UV exposure in standard continuous crosslinking (C-CXL). • This should theoretically enhance the efficacy of the treatment by maintaining higher oxygen levels that are crucial to the cross-linking process. • There are no systematic reviews or meta-analyses directly comparing the efficacy or safety of P-CXL to C-CXL. What is New • Meta-analysis revealed differences in keratometry between P-CXL and C-CXL groups with equivalent fluence (7.2 J/cm2) at 12 months were not statistically significant (Kmax -0.04 dioptres; p = 0.84). • Meta-analysis revealed differences in visual acuity between P-CXL and C-CXL groups with equivalent fluence (7.2 J/cm2) at 12 months were not statistically significant (CDVA -0.01 logMAR letters; p = 0.57). • The use of intermittent pulsing in higher energy CXL protocols renders statistically similar outcomes as continuous light exposure at equivalent fluence (7.2 J/cm2).
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Affiliation(s)
- Maria Qureshi
- Faculty of Medicine and Health, The University of Sydney, Save Sight Institute, Sydney, NSW, Australia
| | - Stephanie L Watson
- Faculty of Medicine and Health, The University of Sydney, Save Sight Institute, Sydney, NSW, Australia.
- Sydney Eye Hospital, the University of Sydney, Save Sight Institute, South Block, Level 1, 8 Macquarie Street, NSW, 2000, Sydney, Australia.
| | - Himal Kandel
- Faculty of Medicine and Health, The University of Sydney, Save Sight Institute, Sydney, NSW, Australia
- Sydney Eye Hospital, the University of Sydney, Save Sight Institute, South Block, Level 1, 8 Macquarie Street, NSW, 2000, Sydney, Australia
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Sánchez-Tena MÁ, Pérez CM, Villa-Collar C, Alvarez-Peregrina C. A bibliometric and citation network analysis of crosslinking. Eur J Ophthalmol 2024:11206721241272177. [PMID: 39140888 DOI: 10.1177/11206721241272177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/15/2024]
Abstract
Purpose: Research on crosslinking has focused mainly on trying to slow the progression of keratoconus. The objective of this bibliometric analysis is to determine the relationships between the different publications and authors. As well as to identify the different areas of research on crosslinking. Methods: Web of Science (WOS) was the database for the search of publications for the period 1972 to December 2023, using the terms: crosslinking, cross-linking, ocular, vision, visual, cornea, ectasia AND Keratoconus. The analysis of the publication was performed using the CitNetExplorer, VOSviewer and CiteSpace software. Results: 7161 publications and 59415 citation networks were found. The year with the most publications is 2021, a total of 571 (7.97%) publications and 135 citation networks. The most cited publication was "Riboflavin/ultraviolet-a-induced collagen crosslinking for the treatment of keratoconus" published by Wollensak et al. in 2003, with a citation index of 1780. Using the Clustering function, five groups were found that cover the main research areas in this field: keratoconus, corneal transplantation, cataracts, corneal inflammation and axial growth. Conclusion: The treatment of keratoconus continues to be the topic of interest in this area of research. However, in recent years there has been an increase in research on how crosslinking helps to slow down axial growth.
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Affiliation(s)
- Miguel Ángel Sánchez-Tena
- Optometría y Vision, Complutense University of Madrid Faculty of Optics and Optometry, Madrid, Comunidad de Madrid, Spain
| | | | - Cesar Villa-Collar
- Faculty of Biomedical and Health Sciences, Universidad Europea de Madrid SLU, Madrid, Spain
| | - Cristina Alvarez-Peregrina
- Optometry and Vision, Complutense University of Madrid Faculty of Optics and Optometry, Madrid, Madrid, Spain
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Yang M, Chen T, Chen X, Pan H, Zhao G, Chen Z, Zhao N, Ye Q, Chen M, Zhang S, Gao R, Meek KM, Hayes S, Ma X, Li X, Wu Y, Zhang Y, Kong N, Tao W, Zhou X, Huang J. Development of graphitic carbon nitride quantum dots-based oxygen self-sufficient platforms for enhanced corneal crosslinking. Nat Commun 2024; 15:5508. [PMID: 38951161 PMCID: PMC11217369 DOI: 10.1038/s41467-024-49645-8] [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: 10/01/2023] [Accepted: 06/13/2024] [Indexed: 07/03/2024] Open
Abstract
Keratoconus, a disorder characterized by corneal thinning and weakening, results in vision loss. Corneal crosslinking (CXL) can halt the progression of keratoconus. The development of accelerated corneal crosslinking (A-CXL) protocols to shorten the treatment time has been hampered by the rapid depletion of stromal oxygen when higher UVA intensities are used, resulting in a reduced cross-linking effect. It is therefore imperative to develop better methods to increase the oxygen concentration within the corneal stroma during the A-CXL process. Photocatalytic oxygen-generating nanomaterials are promising candidates to solve the hypoxia problem during A-CXL. Biocompatible graphitic carbon nitride (g-C3N4) quantum dots (QDs)-based oxygen self-sufficient platforms including g-C3N4 QDs and riboflavin/g-C3N4 QDs composites (RF@g-C3N4 QDs) have been developed in this study. Both display excellent photocatalytic oxygen generation ability, high reactive oxygen species (ROS) yield, and excellent biosafety. More importantly, the A-CXL effect of the g-C3N4 QDs or RF@g-C3N4 QDs composite on male New Zealand white rabbits is better than that of the riboflavin 5'-phosphate sodium (RF) A-CXL protocol under the same conditions, indicating excellent strengthening of the cornea after A-CXL treatments. These lead us to suggest the potential application of g-C3N4 QDs in A-CXL for corneal ectasias and other corneal diseases.
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Affiliation(s)
- Mei Yang
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, NHC Key Laboratory of Myopia and Related Eye Diseases; Key Laboratory of Myopia and Related Eye Diseases, Chinese Academy of Medical Sciences; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200030, China.
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China.
| | - Tingting Chen
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Xin Chen
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, NHC Key Laboratory of Myopia and Related Eye Diseases; Key Laboratory of Myopia and Related Eye Diseases, Chinese Academy of Medical Sciences; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200030, China
| | - Hongxian Pan
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, NHC Key Laboratory of Myopia and Related Eye Diseases; Key Laboratory of Myopia and Related Eye Diseases, Chinese Academy of Medical Sciences; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200030, China
| | - Guoli Zhao
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, NHC Key Laboratory of Myopia and Related Eye Diseases; Key Laboratory of Myopia and Related Eye Diseases, Chinese Academy of Medical Sciences; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200030, China
| | - Zhongxing Chen
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, NHC Key Laboratory of Myopia and Related Eye Diseases; Key Laboratory of Myopia and Related Eye Diseases, Chinese Academy of Medical Sciences; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200030, China
| | - Nan Zhao
- School of Chemical Engineering, Northeast Electric Power University, Jilin, 132000, China
| | - Qianfang Ye
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Ming Chen
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, NHC Key Laboratory of Myopia and Related Eye Diseases; Key Laboratory of Myopia and Related Eye Diseases, Chinese Academy of Medical Sciences; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200030, China
| | - Shenrong Zhang
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Rongrong Gao
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Keith M Meek
- School of Optometry and Vision Sciences, Cardiff University; Cardiff Institute for Tissue Engineering and Repair School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff, CF10 3NB, UK
| | - Sally Hayes
- School of Optometry and Vision Sciences, Cardiff University; Cardiff Institute for Tissue Engineering and Repair School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Redwood Building, King Edward VII Avenue, Cardiff, CF10 3NB, UK
| | - Xiaowei Ma
- School of Environmental Science and Engineering, Nanjing University of Information Science and Technology, Nanjing, 210044, China
| | - Xin Li
- School of Ophthalmology and Optometry and Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, 325027, China
| | - Yue Wu
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, NHC Key Laboratory of Myopia and Related Eye Diseases; Key Laboratory of Myopia and Related Eye Diseases, Chinese Academy of Medical Sciences; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200030, China
| | - Yiming Zhang
- Center for Nanomedicine and Department of Anesthesiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Na Kong
- Center for Nanomedicine and Department of Anesthesiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Wei Tao
- Center for Nanomedicine and Department of Anesthesiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Xingtao Zhou
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, NHC Key Laboratory of Myopia and Related Eye Diseases; Key Laboratory of Myopia and Related Eye Diseases, Chinese Academy of Medical Sciences; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200030, China.
| | - Jinhai Huang
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, NHC Key Laboratory of Myopia and Related Eye Diseases; Key Laboratory of Myopia and Related Eye Diseases, Chinese Academy of Medical Sciences; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200030, China.
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5
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Li JPO, Maile HP, Bunce C, Kandakji L, Leucci MT, Allan BD, Tuft SJ, Pontikos N, Gore DM. A comparison of keratoconus progression following collagen cross-linkage using standard or personalised keratometry thresholds. Eye (Lond) 2024; 38:1681-1686. [PMID: 38409307 PMCID: PMC11156642 DOI: 10.1038/s41433-024-02994-6] [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: 08/07/2023] [Revised: 02/04/2024] [Accepted: 02/13/2024] [Indexed: 02/28/2024] Open
Abstract
OBJECTIVE To define how estimates of keratoconus progression following collagen cross-linking (CXL) vary according to the parameter selected to measure corneal shape. MATERIALS AND METHODS We estimated progression following CXL in 1677 eyes. We compared standard definitions of keratoconus progression based on published thresholds for Kmax, front K2, or back K2, or progression of any two of these three parameters, with the option of an increased threshold for Kmax values ≥ 55D. As corneal thickness reduces unpredictably after CXL, it was excluded from the principal analysis. We then repeated the analysis using novel adaptive estimates of progression for Kmax, front K2, or back K2, developed separately using 6463 paired readings from keratoconus eyes, with a variation of the Bland-Altman method to determine the 95% regression-based limits of agreement (LoA). We created Kaplan-Meier survival plots for both standard and adaptive thresholds. The primary outcome was progression five years after a baseline visit 9-15 months following CXL. RESULTS Progression rates were 8% with a standard (≥ 1.5D) threshold for K2 or 6% with the static multi-parameter definition. With a ≥ 1D threshold for Kmax, the progression was significantly higher at 29%. With adaptive Kmax or K2, the progression rates were similar (20%) but less than with the adaptive multi-parameter method (22%). CONCLUSIONS Estimates of keratoconus progression following CXL vary widely according to the reference criteria. Using adaptive thresholds (LoA) to define the repeatability of keratometry gives estimates for progression that are markedly higher than with the standard multi-parameter method.
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Affiliation(s)
- Ji-Peng Olivia Li
- Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London, EC1V 2PD, UK
| | - Howard P Maile
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
| | - Catey Bunce
- Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London, EC1V 2PD, UK
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
- National Institute for Health and Care Research (NIHR) BRC at the Royal Marsden NHS Foundation Trust and the Institute of Cancer Research, London, UK
| | - Lynn Kandakji
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
| | - Marcello T Leucci
- Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London, EC1V 2PD, UK
| | - Bruce D Allan
- Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London, EC1V 2PD, UK
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
| | - Stephen J Tuft
- Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London, EC1V 2PD, UK.
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK.
| | - Nikolas Pontikos
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
| | - Daniel M Gore
- Moorfields Eye Hospital NHS Foundation Trust, 162 City Road, London, EC1V 2PD, UK
- UCL Institute of Ophthalmology, 11-43 Bath Street, London, EC1V 9EL, UK
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Hagem AM, Thorsrud A, Sæthre M, Sandvik G, Kristianslund O, Drolsum L. Dramatic Reduction in Corneal Transplants for Keratoconus 15 Years After the Introduction of Corneal Collagen Crosslinking. Cornea 2024; 43:437-442. [PMID: 37851565 DOI: 10.1097/ico.0000000000003401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 08/28/2023] [Indexed: 10/20/2023]
Abstract
PURPOSE The aim of this study was to investigate the effect of the implementation of corneal collagen crosslinking (CXL) on the frequency of corneal transplants among patients with keratoconus (KC) in the same region. METHODS Before the introduction of CXL in 2007, 55 primary corneal transplants had been conducted in patients with KC (2005 and 2006) at the Department of Ophthalmology, Oslo University Hospital, Norway. We collected data from our corneal transplant registry for 2021 and 2022. The primary outcome was the number of corneal transplants performed in patients with KC. Age, sex, visual acuity (logarithm of the minimal angle of resolution), KC stage according to the Amsler-Krumeich classification system, and steepest keratometry reading (maximum keratometry, Pentacam, HR) were recorded. Furthermore, we registered the annual number of CXL treatments conducted from 2007 to 2022. RESULTS A total of 352 corneal transplants were performed in 2021 and 2022. Among them, 11 (3.1%) were transplants for patients with KC. All included patients were male; further, 90.1% and 9.1% of the patients were graded stages 4 and 3, respectively. The mean maximum keratometry was 79.0 diopter (range 61.0-109). The mean best-corrected visual acuity (logarithm of the minimal angle of resolution) was 1.3 (range 0.2-3.0). In 2021 to 2022, 431 CXL treatments were performed. CONCLUSIONS There was a significant decrease in the number of corneal transplants performed in patients with KC 15 years after the introduction of CXL. This indicates that the availability of CXL treatment over many years may considerably reduce the need for keratoplasties in this group of patients.
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Affiliation(s)
- Anne Marie Hagem
- Department of Ophthalmology, Oslo University Hospital, Oslo, Norway; and
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Andreas Thorsrud
- Department of Ophthalmology, Oslo University Hospital, Oslo, Norway; and
| | - Marit Sæthre
- Department of Ophthalmology, Oslo University Hospital, Oslo, Norway; and
| | - Gunhild Sandvik
- Department of Ophthalmology, Oslo University Hospital, Oslo, Norway; and
| | - Olav Kristianslund
- Department of Ophthalmology, Oslo University Hospital, Oslo, Norway; and
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Liv Drolsum
- Department of Ophthalmology, Oslo University Hospital, Oslo, Norway; and
- Institute of Clinical Medicine, University of Oslo, Oslo, Norway
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7
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Price LD, Larkin DFP. Diagnosis and management of keratoconus in the paediatric age group: a review of current evidence. Eye (Lond) 2023; 37:3718-3724. [PMID: 37280353 PMCID: PMC10698037 DOI: 10.1038/s41433-023-02600-1] [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: 10/18/2022] [Revised: 04/12/2023] [Accepted: 05/19/2023] [Indexed: 06/08/2023] Open
Abstract
The diagnosis and management of keratoconus in the paediatric age group presents additional challenges to those encountered in adults. The most significant of these, encountered in some young patients, are delayed presentation of unilateral disease, more advanced disease at diagnosis, difficulty in obtaining reliable corneal imaging, faster rates of disease progression and challenges in contact lens management. The stabilisation effect of corneal cross-linking (CXL), more extensively studied in adults with randomised trials and long-term follow-up, has been much less rigorously examined in children and adolescents. The high heterogeneity of published studies in younger patients, particularly in the choice of tomography parameters designated as primary outcome measures and the definitions of progression, indicates that improved standardisation for future studies on CXL will be necessary. There is no evidence that corneal transplant outcomes in young patients are poorer than those in adults. This review provides a current perspective on the optimal diagnosis and treatment of keratoconus in children and adolescents.
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Affiliation(s)
- Liam D Price
- Moorfields Eye Hospital, London, United Kingdom.
| | - Daniel F P Larkin
- NIHR Moorfields Biomedical Research Centre, Moorfields Eye Hospital, London, United Kingdom
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8
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Hayes S, Jaycock P, Rees N, Figueiredo FC, O'Brart DPS, Meek KM. National survey of corneal cross-linking (CXL) practice patterns in the United Kingdom during 2019. Eye (Lond) 2023; 37:2511-2517. [PMID: 36539601 PMCID: PMC9767393 DOI: 10.1038/s41433-022-02365-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 12/06/2022] [Accepted: 12/06/2022] [Indexed: 12/24/2022] Open
Abstract
OBJECTIVE To provide an insight into trends in corneal cross-linking (CXL) practice in the UK, including criteria for progression of corneal ectasia, identification of patients for CXL, the CXL procedure itself and post-operative management. METHODS All ophthalmologist members of the UK Cross-linking (UK-CXL) Consortium were invited to complete an online survey about CXL practice for the year 2019. The data collected was anonymised by site and analysed with descriptive statistics. RESULTS Responses were received from 16 individual CXL centres (16/38; 42% response rate) and the data represented ~2,000 CXL procedures performed in the UK in 2019. The commonest indication for CXL was progressive keratoconus. Between centres, there were variations in diagnostic evaluation, patient selection for CXL, the CXL procedure and the pre- and post-operative monitoring of patients. CONCLUSION Consistent with the wide number of CXL treatment techniques described in the published literature world-wide, variations in the monitoring of corneal ectasia, indications for CXL, CXL practice and post-CXL follow-up were found to exist between UK-based CXL centres.
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Affiliation(s)
- Sally Hayes
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK.
| | - Philip Jaycock
- Nuffield Health Bristol Hospital, 3 Clifton Hill, Clifton, Bristol, BS8 1BN, UK
| | - Nicholas Rees
- Bristol Medical School, University of Bristol, 5 Tyndall Avenue, Bristol, BS8 1UD, UK
| | - Francisco C Figueiredo
- Department of Ophthalmology, Royal Victoria Infirmary, Newcastle upon Tyne Hospitals NHS Foundation Trust, Queen Victoria Road, Newcastle upon Tyne, NE1 4LP, UK
- Bioscience Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - David P S O'Brart
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
- Keratoconus Research Institute, Department of Ophthalmology, St Thomas Hospital, London, SE1 7EH, UK
| | - Keith M Meek
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ, UK
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9
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Abdel-Radi M, Abdelmohsen N, Abdelmotaal H, Abd El-Moneim MT. The effect of accelerated pulsed high-fluence corneal cross-linking on corneal endothelium; a prospective specular microscopy study. BMC Ophthalmol 2023; 23:163. [PMID: 37072730 PMCID: PMC10114460 DOI: 10.1186/s12886-023-02912-6] [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: 12/24/2022] [Accepted: 04/07/2023] [Indexed: 04/20/2023] Open
Abstract
BACKGROUND Corneal collagen cross-linking (CXL) is a procedure utilized for halting keratoconus progression with different approved protocols. The current study aimed to assess the corneal endothelial changes following the relatively new accelerated pulsed high-fluence protocol of epithelium-off corneal cross-linking for the treatment of mild to moderate keratoconus. METHODS This prospective case series study enrolled 45 eyes of 27 patients with mild to moderate progressive keratoconus who underwent accelerated pulsed high-fluence CXL (pl-ACXL, 30 mW/ cm2 UVA at 365 nm wavelength, 8 min pulsed mode 1 s on / 1 s off with a total energy of 7.2 J/ cm2). The main outcome measures were corneal endothelial changes assessed by specular microscopy at 3 and 6 months postoperatively including endothelial cell density (ECD), coefficient of variation, percentage of hexagonal cells, average, minimum and maximum endothelial cell sizes. Demarcation line depth was assessed 1 month following surgery. RESULTS The mean age of the studied sample was 24.89 ± 7.21. The mean preoperative ECD (2944.6 ± 247.41 cell/mm2) showed non-significant reduction at 3 and 6 months postoperatively (2931.03 ± 253.82 and 2924.7 ± 224.88 cell/mm2, respectively, P-value = 0.361). There were no significant changes in the mean coefficient of variation, percentage of hexagonal cells, average, minimum and maximum endothelial cell sizes at 3 and 6 months following pl-ACXL (P-value > 0.05). The mean demarcation line depth 1 month after pl-ACXL was 214 ± 17.43 μm. CONCLUSIONS Corneal endothelial changes following accelerated pulsed high-fluence CXL were minimal with stability of endothelial cell count and non-significant morphological changes. TRIAL REGISTRATION Clinicaltrials.gov: NCT04160338 (13/11/2019).
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Affiliation(s)
- Mahmoud Abdel-Radi
- Department of Ophthalmology, Assiut University, Assiut University Hospital 6th floor, Assiut, 71516, Egypt.
| | - Naglaa Abdelmohsen
- Department of Ophthalmology, Assiut University, Assiut University Hospital 6th floor, Assiut, 71516, Egypt
| | - Hazem Abdelmotaal
- Department of Ophthalmology, Assiut University, Assiut University Hospital 6th floor, Assiut, 71516, Egypt
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10
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Efficacy and Safety of Standard Corneal Cross-Linking Procedures Performed With Short Versus Standard Riboflavin Induction: A Save Sight Keratoconus Registry Study. Cornea 2023; 42:326-331. [PMID: 35588392 DOI: 10.1097/ico.0000000000003058] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 03/21/2022] [Indexed: 11/26/2022]
Abstract
PURPOSE The objective of this study was to compare the effectiveness and safety of short versus standard riboflavin induction times in cross-linking (CXL) for keratoconus. METHODS A retrospective comparative study was conducted with data from the Save Sight Keratoconus Registry. Inclusion criteria were epithelium-off technique, standard UVA CXL protocol (3 mW/cm 2 for 30 minutes), riboflavin induction for 15 minutes (short) or 30 minutes (standard), and 1 year of follow-up data after CXL. Outcome measures included changes in best-corrected visual acuity (BCVA), keratometry in the steepest meridian (K2), maximum keratometry (Kmax), thinnest pachymetry (TCT), and adverse events. Analysis was conducted using mixed-effects regression models adjusted for age, sex, visual acuity, keratometry, pachymetry, practice, and eye laterality. RESULTS Two hundred eighty eyes (237 patients; mean, 27.3 ± 10.5 years old; 30% female) were included. The riboflavin induction time was short in 102 eyes (82 patients) and standard in 178 eyes (155 patients). The baseline characteristics (sex, mean age, BCVA, keratometry, and pachymetry [TCT]) were similar between the groups. At the 1-year follow-up visit, no statistically significant differences were observed in flattening in K2 and improvement in BCVA. Greater Kmax flattening [-1.5 diopters (D) vs. -0.5D, P = 0.031] and a greater proportion of >2% increase in TCT (23.5 vs. 11.3, P = 0.034) and haze (29 vs. 15, P = 0.005) were observed with short riboflavin induction. CONCLUSIONS Short and standard riboflavin induction times achieved similar degrees of flattening in K2 and improvement in vision. Greater improvements in Kmax and TCT were seen with short riboflavin times; however, this group had higher rates of haze.
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11
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Liu G, Li T, Qi B, Gong G, Guo T, Zhou Q, Jhanji V, Zhang BN, Du X. Norepinephrine as an Enhancer Promoting Corneal Penetration of Riboflavin for Transepithelial Corneal Crosslinking. Transl Vis Sci Technol 2023; 12:21. [PMID: 36786745 PMCID: PMC9932548 DOI: 10.1167/tvst.12.2.21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
Purpose Previously, we found norepinephrine (NE) could affect the corneal epithelial integrity, herein we investigated the feasibility and safety of NE serving as a chemical enhancer to promote corneal penetration of riboflavin during transepithelial corneal crosslinking (CXL). Methods The dosage of NE that could promote riboflavin diffusion through the healthy epithelial barrier without inducing epithelial damage in C57BL/6 mice was determined. The safety of NE treatment was confirmed by morphological and histological examinations of the whole cornea. The efficacy of NE in promoting riboflavin penetration was verified by slit lamp and scanning electron microscope (SEM), and corneal biomechanical measurement after CXL. To better fit the clinical scenario, increased NE dosage and shortened riboflavin infiltration time were further evaluated. Results The lowest dosage of NE (1 mg/mL) that facilitated transepithelial riboflavin permeation was 2 µL. No visible corneal structure alteration was observed after NE treatment. SEM indicated dissociation of intercellular junctions among corneal epithelial cells. Homogenous distribution of riboflavin throughout corneal stroma was observed. NE-treated corneas reached comparable biomechanical properties after CXL, including stress-relaxation curve and elastic modulus, with corneas treated with the commercially available transepithelial drug Peschke TE. To better fit the clinical scenario, increasing NE up to 5.5 µL helped riboflavin infiltrate the corneal stroma within 30 minutes. After CXL with 9 mW/cm2 ultraviolet-A (UVA) for 2.5 minutes, the cornea showed significantly enhanced corneal biomechanical properties with undisturbed corneal endothelium. Conclusions NE serves as an effective enhancer in increasing riboflavin diffusion with limited impairment on corneal epithelium and has great potential for clinical application. Translation Relevance NE serves as an effective enhancer for riboflavin penetration and clinical transepithelial CXL.
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Affiliation(s)
- Guoying Liu
- Medical College, Qingdao University, Qingdao, China,Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China
| | - Tan Li
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China,State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Qingdao, China,School of Ophthalmology, Shandong First Medical University, Qingdao, China
| | - Benxiang Qi
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China,State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Qingdao, China,School of Ophthalmology, Shandong First Medical University, Qingdao, China
| | - Ganyu Gong
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China,School of Ophthalmology, Shandong First Medical University, Qingdao, China
| | - Tengyou Guo
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China,School of Ophthalmology, Shandong First Medical University, Qingdao, China
| | - Qingjun Zhou
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China,State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Qingdao, China,School of Ophthalmology, Shandong First Medical University, Qingdao, China
| | - Vishal Jhanji
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Bi Ning Zhang
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China,State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Qingdao, China,School of Ophthalmology, Shandong First Medical University, Qingdao, China
| | - Xianli Du
- Eye Institute of Shandong First Medical University, Qingdao Eye Hospital of Shandong First Medical University, Qingdao, China,State Key Laboratory Cultivation Base, Shandong Provincial Key Laboratory of Ophthalmology, Qingdao, China,School of Ophthalmology, Shandong First Medical University, Qingdao, China
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12
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Zhang X, Sun L, Chen L, Zhang C, Xian Y, Aruma A, Wei R, Shen Y, Chen W, Zhou X. Corneal biomechanical stiffness and histopathological changes after in vivo repeated accelerated corneal cross-linking in cat eyes. Exp Eye Res 2023; 227:109363. [PMID: 36584907 DOI: 10.1016/j.exer.2022.109363] [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: 05/14/2022] [Revised: 11/09/2022] [Accepted: 12/20/2022] [Indexed: 12/29/2022]
Abstract
Corneal cross-linking (CXL) has been proved efficiency for treating progressive keratoconus and other corneal ectasia diseases by stabilizing corneal geometry and biomechanics. However, the necessity of repeated CXL treatment in patients is unknown. This study aimed to investigate corneal biomechanical stiffness and change in corneal histopathological characteristics after repeated accelerated CXL (A-CXL) in cat eyes. A-CXL was performed with 0.1% riboflavin applied for 10 min, followed by ultraviolet A irradiation at 30 mW/cm2 for 3 min at 365 nm in 15 domestic cats. Corneas (n = 30) were divided into three groups: one-time accelerated corneal cross-linking (A-CXL*1 group), repeated accelerated corneal cross-linking (A-CXL*2 group), and an untreated control group. In A-CXL*2 group, A-CXL was repeated at 1-month intervals. In vivo ocular examinations were performed pre- and postoperatively. Biomechanical analysis was performed using a biotester biaxial testing system. We used the Mooney-Rivlin strain-energy function to describe corneal material properties. No infection in any case after A-CXL was observed. Biomechanical tests showed that the stress-strain curves of the two A-CXL groups were significantly different from those of the control group (P < 0.01), whereas stress-strain curve of the A-CXL*2 group was similar to that of the A-CXL*1 group (P > 0.05). Delayed epithelial healing and haze were observed 1 month after surgery. Stromal demarcation line depth measured with anterior spectral-domain optical coherence tomography was 187.6 ± 20.4 and 197.1 ± 11.5 μm for the A-CXL*1 and A-CXL*2 groups, respectively (P > 0.05). These results show that A-CXL can increase corneal biomechanics in cat eyes. The biomechanical enhancement of cat corneas treated with repeated A-CXL at 1-month intervals was similar to that of performing a one-time A-CXL. Repeated cross-linking procedures at short intervals may increase the risk of adverse reactions, and more caution should be taken in clinical applications.
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Affiliation(s)
- Xiaoyu Zhang
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, 200031, China; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200031, China; Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, 200031, China
| | - Ling Sun
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, 200031, China; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200031, China; Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, 200031, China
| | - Lingfeng Chen
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, 030024, China
| | - Chaoqin Zhang
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, 030024, China
| | - Yiyong Xian
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, 200031, China; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200031, China; Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, 200031, China
| | - Aruma Aruma
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, 200031, China; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200031, China; Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, 200031, China
| | - Ruoyan Wei
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, 200031, China; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200031, China; Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, 200031, China
| | - Yang Shen
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, 200031, China; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200031, China; Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, 200031, China
| | - Weiyi Chen
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi, 030024, China
| | - Xingtao Zhou
- Eye Institute and Department of Ophthalmology, Eye & ENT Hospital, Fudan University, Shanghai, 200031, China; NHC Key Laboratory of Myopia (Fudan University), Key Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, 200031, China; Shanghai Research Center of Ophthalmology and Optometry, Shanghai, 200031, China; Shanghai Engineering Research Center of Laser and Autostereoscopic 3D for Vision Care (20DZ2255000), Shanghai, 200031, China.
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Cronin B, Ghosh A, Chang CY. Oxygen-supplemented transepithelial-accelerated corneal crosslinking with pulsed irradiation for progressive keratoconus: 1 year outcomes. J Cataract Refract Surg 2022; 48:1175-1182. [PMID: 35383648 DOI: 10.1097/j.jcrs.0000000000000952] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 03/29/2022] [Indexed: 11/25/2022]
Abstract
PURPOSE To investigate the effects of combining oxygen supplementation with enhanced UV-A light and increased riboflavin permeability in improving the efficacy of epithelium-on crosslinking (epi-on CXL). SETTING Private eye clinic in Brisbane, Queensland, Australia. DESIGN Retrospective single-center nonrandomized uncontrolled longitudinal cohort case series. METHODS Transepithelial CXL was performed on keratoconic eyes. Applications of an oxygen goggle and pulsed UV-A irradiation (1 second on, 1 second off) were used to enhance oxygen kinetics during epi-on CXL. Additional procedural modifications included the use of benzalkonium chloride and high UV-A irradiance level (30 mW/cm 2 ) to improve the stromal bioavailability of riboflavin and UV-A. The main efficacy outcomes were the changes in mean corrected distance visual acuity (CDVA) and safety over 12 months. Additional refractive and keratometry (K) outcomes were also observed. RESULTS 53 eyes (38 patients) were included in this study. 12 months postoperatively, mean CDVA improved from a mean of 0.18 ± 0.2 at baseline to 0.07 ± 0.1 logMAR ( P < .0001). No statistically significant change was observed in maximum K (Kmax) and mean K, which were respectively 51.7 ± 5.8 diopters (D) and 46.4 ± 3.85 D at baseline and 51.2 ± 5.7 D ( P = .152) and 46.0 ± 3.84 D ( P = .06) 12 months postoperatively. Only 3 eyes experienced an increase of more than 2 D in Kmax; however, none of these eyes experienced a CDVA loss. There were no reported infections, corneal scarring, or other severe adverse effects. CONCLUSIONS Performing supplemental oxygen epi-on CXL with accelerated, pulsed UV-A irradiation in conjunction with riboflavin permeability enhancers resulted in improved CDVA ( P < .0001) and stable keratometry up to 12 months postoperatively with a good safety profile.
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Affiliation(s)
- Brendan Cronin
- From the Queensland Eye Institute, Brisbane, Queensland, Australia (Cronin, Ghosh); Glaukos Corp., Medical Affairs, Burlington, Massachusetts (Chang); Wills Eye Hospital, Cornea Service, Philadelphia, Pennsylvania (Chang)
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14
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Wallerstein A, Gauvin M, Rocha G, Sison R, Korban S, Cohen M. Three-Year Outcomes of Under-flap Stromal Bed CXL for Early Post-LASIK Ectasia. J Refract Surg 2022; 38:511-519. [PMID: 35946998 DOI: 10.3928/1081597x-20220713-01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To investigate the 36-month clinical outcomes of under-flap stromal bed CXL (ufCXL) and report on its ability to stabilize post-laser in situ keratomileusis (LASIK) ectasia. METHODS This case series included 20 eyes with diagnosed early post-LASIK ectasia treated with ufCXL. Inclusion criteria were early, mild post-LASIK ectasia, defined as new-onset postoperative manifest refraction cylinder of 1.50 diopters (D) or less, with new topographic inferior steepening consistent with ectasia, uncorrected distance visual acuity of 20/40 or better, and corrected distance visual acuity of 20/25 or better. The existing LASIK flap was lifted, 0.25% isotonic riboflavin was applied directly to the stromal bed, the flap was repositioned, and 18 mW/cm2 ultraviolet light was applied for 5 minutes to the corneal flap surface. Post-ufCXL ophthalmic data were compared to pre-ufCXL baseline measurements. RESULTS Visual outcomes were maintained pre-ufCXL to 36 months post-ufCXL, with preserved safety index (P = .6545), efficacy index (P = .4980), spherical equivalent accuracy (P = .1536), defocus equivalent accuracy (P = .1032), central corneal thickness (P = .5196), and corneal irregularity indices at 3 mm (P = .8548) and 5 mm (P = .3399). Refractive astigmatism significantly decreased from 0.83 to 0.55 D pre-ufCXL to post-ufCXL (P = .0439), as did maximum keratometry from 42.40 to 42.00 D pre-ufCXL to post-ufCXL (P = .0420). The ufCXL demarcation line depth was 336 ± 21 µm post-ufCXL, with normal endothelial cell density (2,574 ± 203 cells/mm2). Only 1 of 20 eyes showed evidence of progression of 1.00 D in maximum keratometry. CONCLUSIONS The ufCXL procedure shows promise in stabilizing early post-LASIK ectasia. Visual function, refractive astigmatism, maximum keratometry, and corneal irregularity indices were statistically maintained at 36 months postoperatively. [J Refract Surg. 2022;38(8):511-519.].
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15
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Maile HP, Li JPO, Fortune MD, Royston P, Leucci MT, Moghul I, Szabo A, Balaskas K, Allan BD, Hardcastle AJ, Hysi P, Pontikos N, Tuft SJ, Gore DM. Personalized Model to Predict Keratoconus Progression From Demographic, Topographic, and Genetic Data. Am J Ophthalmol 2022; 240:321-329. [PMID: 35469790 DOI: 10.1016/j.ajo.2022.04.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 04/02/2022] [Accepted: 04/13/2022] [Indexed: 11/26/2022]
Abstract
PURPOSE To generate a prognostic model to predict keratoconus progression to corneal crosslinking (CXL). DESIGN Retrospective cohort study. METHODS We recruited 5025 patients (9341 eyes) with early keratoconus between January 2011 and November 2020. Genetic data from 926 patients were available. We investigated both keratometry or CXL as end points for progression and used the Royston-Parmar method on the proportional hazards scale to generate a prognostic model. We calculated hazard ratios (HRs) for each significant covariate, with explained variation and discrimination, and performed internal-external cross validation by geographic regions. RESULTS After exclusions, model fitting comprised 8701 eyes, of which 3232 underwent CXL. For early keratoconus, CXL provided a more robust prognostic model than keratometric progression. The final model explained 33% of the variation in time to event: age HR (95% CI) 0.9 (0.90-0.91), maximum anterior keratometry 1.08 (1.07-1.09), and minimum corneal thickness 0.95 (0.93-0.96) as significant covariates. Single-nucleotide polymorphisms (SNPs) associated with keratoconus (n=28) did not significantly contribute to the model. The predicted time-to-event curves closely followed the observed curves during internal-external validation. Differences in discrimination between geographic regions was low, suggesting the model maintained its predictive ability. CONCLUSIONS A prognostic model to predict keratoconus progression could aid patient empowerment, triage, and service provision. Age at presentation is the most significant predictor of progression risk. Candidate SNPs associated with keratoconus do not contribute to progression risk.
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16
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Jackson AJ, Anand V. Keratoconus: To conquer the cone. Cont Lens Anterior Eye 2022; 45:101578. [PMID: 35210169 DOI: 10.1016/j.clae.2022.101578] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Vijay Anand
- Deputy Head of Optometry, Moorfields Eye Hospital NHSFT, United Kingdom.
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17
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Maile H, Li JPO, Gore D, Leucci M, Mulholland P, Hau S, Szabo A, Moghul I, Balaskas K, Fujinami K, Hysi P, Davidson A, Liskova P, Hardcastle A, Tuft S, Pontikos N. Machine Learning Algorithms to Detect Subclinical Keratoconus: Systematic Review. JMIR Med Inform 2021; 9:e27363. [PMID: 34898463 PMCID: PMC8713097 DOI: 10.2196/27363] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 05/10/2021] [Accepted: 10/14/2021] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND Keratoconus is a disorder characterized by progressive thinning and distortion of the cornea. If detected at an early stage, corneal collagen cross-linking can prevent disease progression and further visual loss. Although advanced forms are easily detected, reliable identification of subclinical disease can be problematic. Several different machine learning algorithms have been used to improve the detection of subclinical keratoconus based on the analysis of multiple types of clinical measures, such as corneal imaging, aberrometry, or biomechanical measurements. OBJECTIVE The aim of this study is to survey and critically evaluate the literature on the algorithmic detection of subclinical keratoconus and equivalent definitions. METHODS For this systematic review, we performed a structured search of the following databases: MEDLINE, Embase, and Web of Science and Cochrane Library from January 1, 2010, to October 31, 2020. We included all full-text studies that have used algorithms for the detection of subclinical keratoconus and excluded studies that did not perform validation. This systematic review followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) recommendations. RESULTS We compared the measured parameters and the design of the machine learning algorithms reported in 26 papers that met the inclusion criteria. All salient information required for detailed comparison, including diagnostic criteria, demographic data, sample size, acquisition system, validation details, parameter inputs, machine learning algorithm, and key results are reported in this study. CONCLUSIONS Machine learning has the potential to improve the detection of subclinical keratoconus or early keratoconus in routine ophthalmic practice. Currently, there is no consensus regarding the corneal parameters that should be included for assessment and the optimal design for the machine learning algorithm. We have identified avenues for further research to improve early detection and stratification of patients for early treatment to prevent disease progression.
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Affiliation(s)
- Howard Maile
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
| | | | - Daniel Gore
- Moorfields Eye Hospital, London, United Kingdom
| | | | - Padraig Mulholland
- UCL Institute of Ophthalmology, University College London, London, United Kingdom.,Moorfields Eye Hospital, London, United Kingdom.,Centre for Optometry & Vision Science, Biomedical Sciences Research Institute, Ulster University, Coleraine, United Kingdom
| | - Scott Hau
- Moorfields Eye Hospital, London, United Kingdom
| | - Anita Szabo
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
| | | | | | - Kaoru Fujinami
- UCL Institute of Ophthalmology, University College London, London, United Kingdom.,Moorfields Eye Hospital, London, United Kingdom.,Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, National Hospital Organization Tokyo Medical Center, Tokyo, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Pirro Hysi
- Section of Ophthalmology, School of Life Course Sciences, King's College London, London, United Kingdom.,Department of Twin Research and Genetic Epidemiology, King's College London, London, United Kingdom
| | - Alice Davidson
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
| | - Petra Liskova
- Department of Paediatrics and Inherited Metabolic Disorders, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic.,Department of Ophthalmology, First Faculty of Medicine, Charles University and General University Hospital, Prague, Czech Republic
| | - Alison Hardcastle
- UCL Institute of Ophthalmology, University College London, London, United Kingdom
| | - Stephen Tuft
- UCL Institute of Ophthalmology, University College London, London, United Kingdom.,Moorfields Eye Hospital, London, United Kingdom
| | - Nikolas Pontikos
- UCL Institute of Ophthalmology, University College London, London, United Kingdom.,Moorfields Eye Hospital, London, United Kingdom
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18
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Nicula CA, Rednik AM, Nicula AP, Bulboaca AE, Nicula D, Horvath KU. Comparative Results Between "Epi-Off" Accelerated and "Epi-Off" Standard Corneal Collagen Crosslinking-UVA in Progressive Keratoconus - 7 Years of Follow-Up. Ther Clin Risk Manag 2021; 17:975-988. [PMID: 34522101 PMCID: PMC8434931 DOI: 10.2147/tcrm.s321410] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 08/14/2021] [Indexed: 11/23/2022] Open
Abstract
Purpose The purpose of the present study was to assess the long-term efficiency and safety of the “epi-off” accelerated CXL (9 mW/cm2 for 10 minutes) in comparison to the standard “epi-off” CXL (3 mW/cm2 for 30 minutes) in terms of topographical and keratometric parameters, refractive data and visual outcomes at 7 years of follow-up, in progressive keratoconus. Material and Method A retrospective and comparative study was performed. A total of 183 eyes from 183 patients with documented progressive keratoconus were included in the study. The patients were divided in two groups: 93 eyes from 93 patients underwent “epi-off” standard cross-linking technique (3 mW/cm2 for 30 minutes) (S-CXL group) and 90 eyes from 90 patients underwent accelerated “epi-off” corneal CXL technique (9 mW/cm2 for 10 minutes) (A-CXL group). Results Improvements in uncorrected distance visual acuity (UDVA) were statistically significant compared to baseline values in both groups at each time-point visit (p=0.0421 at 1 year, p=0.0411 at 7 years for A-CXL and p=0.0375 at 1 year, p=0.0389 at 7 years for S-CXL). At 7 years there was a statistically significant increase in CDVA (p=0.039 in the A-CXL group and p=0.0343 in the S-CXL group at 7 years). Statistically significant reduction was noticed in Ksteep (p=0.0411 in A-CXL group and p=0.0224 in S-CXL group), Kflat (p=0.0198 in A-CXL group and p=0.008 in S-CXL group), K mean (p=0.0106 in A-CXL group and p=0.0193 in S-CXL group) and Kmax (p=0.0413 in A-CXL group and p=0.054 in S-CXL group) at 7 years, compared to baseline values, in both groups, but without any statistically difference between the two procedures, at all time-point visits (p>0.05). Conclusion The long-term outcomes of “epi-off” accelerated corneal collagen crosslinking-UVA (9 mW/cm2 for 10 minutes) are similar to standard “epi-off” corneal collagen crosslinking procedure in the treatment of progressive keratoconus.
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Affiliation(s)
- Cristina Ariadna Nicula
- Department of Ophthalmology, Medicine and Pharmacy University "Iuliu Hațieganu", Cluj-Napoca, Romania.,Oculens Clinic, Cluj-Napoca, Romania
| | - Anca Maria Rednik
- Eye County Hospital, Department of Ophthalmology, Cluj-Napoca, Romania
| | | | - Adriana Elena Bulboaca
- Department of Pathophysiology, Medicine and Pharmacy University "Iuliu Hațieganu", Cluj Napoca, Romania
| | | | - Karin Ursula Horvath
- Department of Ophthalmology, Medicine and Pharmacy Science and Technology University "George Emil Palade", Târgu Mureș, Romania
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19
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Wu D, Lim DKA, Lim BXH, Wong N, Hafezi F, Manotosh R, Lim CHL. Corneal Cross-Linking: The Evolution of Treatment for Corneal Diseases. Front Pharmacol 2021; 12:686630. [PMID: 34349648 PMCID: PMC8326410 DOI: 10.3389/fphar.2021.686630] [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: 03/27/2021] [Accepted: 07/05/2021] [Indexed: 01/31/2023] Open
Abstract
Corneal cross-linking (CXL) using riboflavin and ultraviolet A (UVA) light has become a useful treatment option for not only corneal ectasias, such as keratoconus, but also a number of other corneal diseases. Riboflavin is a photoactivated chromophore that plays an integral role in facilitating collagen crosslinking. Modifications to its formulation and administration have been proposed to overcome shortcomings of the original epithelium-off Dresden CXL protocol and increase its applicability across various clinical scenarios. Hypoosmolar riboflavin formulations have been used to artificially thicken thin corneas prior to cross-linking to mitigate safety concerns regarding the corneal endothelium, whereas hyperosmolar formulations have been used to reduce corneal oedema when treating bullous keratopathy. Transepithelial protocols incorporate supplementary topical medications such as tetracaine, benzalkonium chloride, ethylenediaminetetraacetic acid and trometamol to disrupt the corneal epithelium and improve corneal penetration of riboflavin. Further assistive techniques include use of iontophoresis and other wearable adjuncts to facilitate epithelium-on riboflavin administration. Recent advances include, Photoactivated Chromophore for Keratitis-Corneal Cross-linking (PACK-CXL) for treatment of infectious keratitis, customised protocols (CurV) utilising riboflavin coupled with customised UVA shapes to induce targeted stiffening have further induced interest in the field. This review aims to examine the latest advances in riboflavin and UVA administration, and their efficacy and safety in treating a range of corneal diseases. With such diverse riboflavin delivery options, CXL is well primed to complement the armamentarium of therapeutic options available for the treatment of a variety of corneal diseases.
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Affiliation(s)
- Duoduo Wu
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Dawn Ka-Ann Lim
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Department of Ophthalmology, National University Health System, Singapore, Singapore
| | - Blanche Xiao Hong Lim
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Department of Ophthalmology, National University Health System, Singapore, Singapore
| | - Nathan Wong
- Royal Victorian Eye Hospital, Melbourne, VIC, Australia
| | - Farhad Hafezi
- Ocular Cell Biology Group, Center for Applied Biotechnology and Molecular Medicine, University of Zurich, Zurich, Switzerland.,ELZA Institute, Dietikon, Switzerland.,Faculty of Medicine, University of Geneva, Geneva, Switzerland.,Ophthalmology, USC Roski Eye Institute, Los Angeles, CA, United States.,Ophthalmology, Wenzhou Medical University, Wenzhou, China
| | - Ray Manotosh
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Department of Ophthalmology, National University Health System, Singapore, Singapore
| | - Chris Hong Long Lim
- Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.,Department of Ophthalmology, National University Health System, Singapore, Singapore.,Singapore Eye Research Institute, Singapore, Singapore.,School of Optometry and Vision Science, University of New South Wales, Sydney, NSW, Australia
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Pasha H, Palazzolo L, Prakash G, Jhanji V. Update on corneal collagen crosslinking for ectasia. Curr Opin Ophthalmol 2021; 32:343-347. [PMID: 33966013 DOI: 10.1097/icu.0000000000000765] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Corneal collagen crosslinking (CXL) is a minimally invasive treatment that can stabilize corneal ectatic disorders including keratoconus, pellucid marginal degeneration, or postrefractive surgery ectasia. The benefits of CXL have been well documented. New research is focused on modifying current treatment protocols with the goals of maximizing corneal stability while also shortening overall procedure time. RECENT FINDINGS Accelerated CXL protocols have the goal of delivering the same ultraviolet A intensity as conventional protocols, but over a shorter time period. Accelerated protocols have shown success to date, but there are concerns for long-term corneal stability. Pulsed protocols may increase the long-term efficacy of the accelerated designs. In addition, transepithelial crosslinking protocols have been designed with the goal of reducing postoperative pain and lower the risk of infectious complications of epithelial-off conventional protocols. SUMMARY Newer CXL protocols attempt to make the procedure safer and more effective. Current research is promising, but long-term studies are essential to understand how the new protocols may affect corneal stability.
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Affiliation(s)
- Hamza Pasha
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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21
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Hayes S, Morgan SR, Meek KM. Keratoconus: cross-linking the window of the eye. THERAPEUTIC ADVANCES IN RARE DISEASE 2021; 2:26330040211003573. [PMID: 37181107 PMCID: PMC10032441 DOI: 10.1177/26330040211003573] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 02/25/2021] [Indexed: 05/16/2023]
Abstract
Keratoconus is a condition in which the cornea progressively thins and weakens, leading to severe, irregular astigmatism and a significant reduction in quality of life. Although the precise cause of keratoconus is still not known, biochemical and structural studies indicate that overactive enzymes within the cornea break down the constituent proteins (collagen and proteoglycans) and cause the tissue to weaken. As the disease develops, collagen fibres slip past each other and are redistributed across the cornea, causing it to change shape. In recent years, it was discovered that the photochemical induction of cross-links within the corneal extracellular matrix, through the use of riboflavin and ultraviolet (UVA) light, could increase the strength and enzymatic resistance of the tissue and thereby halt keratoconus progression. Worldwide acceptance and use of riboflavin/UVA corneal cross-linking therapy for halting keratoconus progression has increased rapidly, in accordance with the growing body of evidence supporting its long-term effectiveness. This review focusses on the inception of riboflavin/UVA corneal cross-linking therapy for keratoconus, its clinical effectiveness and the latest scientific advances aimed at reducing patient treatment time, improving patient comfort and increasing patient eligibility for treatment. Plain language summary Review of current treatments using cross-linking to halt the progress of keratoconus Keratoconus is a disease in which the curved cornea, the transparent window at the front of the eye, weakens, bulges forward into a cone-shape and becomes thinner. This change of curvature means that light is not focussed onto the retina correctly and vision is progressively impaired. Traditionally, the effects of early keratoconus were alleviated by using glasses, specialist contact lenses, rings inserted into the cornea and in severe cases, by performing a corneal transplant. However, it was discovered that by inducing chemical bonds called cross-links within the cornea, the tissue could be strengthened and further thinning and shape changes prevented. The standard cross-linking procedure takes over an hour to perform and involves the removal of the cells at the front of the cornea, followed by the application of Vitamin B2 eye drops and low energy ultraviolet light (UVA) to create new cross-links within the tissue. Clinical trials have shown this standard procedure to be safe and effective at halting keratoconus progression. However, there are many treatment modifications currently under investigation that aim to reduce patient treatment time and increase comfort, such as accelerated cross-linking procedures and protocols that do not require removal of the surface cells. This review describes the different techniques being developed to carry out corneal cross-linking efficiently and painlessly, to halt keratoconus progression and avoid the need for expensive surgery.
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Affiliation(s)
- Sally Hayes
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Maindy Road, Cardiff, CF24 4HQ. UK
| | - Siân R Morgan
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
| | - Keith M Meek
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
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Atalay E, Özalp O, Yıldırım N. Advances in the diagnosis and treatment of keratoconus. Ther Adv Ophthalmol 2021; 13:25158414211012796. [PMID: 34263132 PMCID: PMC8246497 DOI: 10.1177/25158414211012796] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 04/07/2021] [Indexed: 01/31/2023] Open
Abstract
Keratoconus had traditionally been considered a rare disease at a time when the imaging technology was inept in detecting subtle manifestations, resulting in more severe disease at presentation. The increased demand for refractive surgery in recent years also made it essential to more effectively detect keratoconus before attempting any ablative procedure. Consequently, the armamentarium of tools that can be used to diagnose and treat keratoconus has significantly expanded. The advances in imaging technology have allowed clinicians and researchers alike to visualize the cornea layer by layer looking for any early changes that might be indicative of keratoconus. In addition to the conventional geometrical evaluation, efforts are also underway to enable spatially resolved corneal biomechanical evaluation. Artificial intelligence has been exploited in a multitude of ways to enhance diagnostic efficiency and to guide treatment. As for treatment, corneal cross-linking treatment remains the mainstay preventive approach, yet the current main focus of research is on increasing oxygen availability and developing new strategies to improve riboflavin permeability during the procedure. Some new combined protocols are being proposed to simultaneously halt keratoconus progression and correct refractive error. Bowman layer transplantation and additive keratoplasty are newly emerging alternatives to conventional keratoplasty techniques that are used in keratoconus surgery. Advances in tissue engineering and regenerative therapy might bring new perspectives for treatment at the cellular level and hence obviate the need for invasive surgeries. In this review, we describe the advances in the diagnosis and treatment of keratoconus primarily focusing on newly emerging approaches and strategies.
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Affiliation(s)
- Eray Atalay
- Department of Ophthalmology, Medical School, Eskişehir Osmangazi University, Meşelik Kampüsü, Odunpazarı, Eskişehir 26040, Turkey
| | - Onur Özalp
- Department of Ophthalmology, Medical School, Eskişehir Osmangazi University, Eskişehir, Turkey
| | - Nilgün Yıldırım
- Department of Ophthalmology, Medical School, Eskişehir Osmangazi University, Eskişehir, Turkey
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