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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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Lombardo M, Serrao S, Bernava GM, Lombardo G. Spatial targeted delivery of riboflavin with a controlled corneal iontophoresis delivery system in theranostic-guided UV-A light photo-therapy. JOURNAL OF BIOPHOTONICS 2024:e202400068. [PMID: 38697616 DOI: 10.1002/jbio.202400068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2024] [Revised: 03/23/2024] [Accepted: 04/09/2024] [Indexed: 05/05/2024]
Abstract
Seven human donor eye globes underwent corneal cross-linking using theranostic UV-A device with accessory corneal iontophoresis system for patterned delivery of a 0.22% riboflavin solution. Theranostic-guided UV-A light illumination assessed riboflavin distribution and treated corneas at 10 mW/cm2 for 9 min with a 5.0-mm beam size. Corneal topography maps were taken at baseline and 2-h post-treatment. Analysis utilized corneal topography elevation data, with results showing controlled riboflavin delivery led to a consistent gradient, with 40% higher levels centrally (248 ± 79 μg/cm3) than peripherally (180 ± 72 μg/cm3 at ±2.5 mm from the center). Theranostic-guided UV-A light irradiation resulted in significant changes in corneal topography, with a decrease in best-fit sphere value (-0.7 ± 0.2 D; p < 0.001) and consistent downward shift in corneal elevation map (-11.7 ± 3.7 μm). The coefficient of variation was 2.5%, indicating high procedure performance in achieving significant and reliable corneal flattening.
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Affiliation(s)
- Marco Lombardo
- Studio Italiano di Oftalmologia, Rome, Italy
- Vision Engineering Italy srl, Rome, Italy
| | - Sebastiano Serrao
- Studio Italiano di Oftalmologia, Rome, Italy
- Vision Engineering Italy srl, Rome, Italy
| | | | - Giuseppe Lombardo
- Studio Italiano di Oftalmologia, Rome, Italy
- CNR-IPCF, Istituto per i Processi Chimico-Fisici, Messina, Italy
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Nanavaty MA, Ashena Z, Bekono-Nessah I, Harding J. Development of a Web-Based Algorithm for Understanding the Intraocular Lens-Based Surgery in Stable and Progressing Keratoconus for Non-Specialist Ophthalmologists. Curr Eye Res 2024; 49:140-149. [PMID: 37870048 DOI: 10.1080/02713683.2023.2270727] [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: 01/04/2023] [Accepted: 10/10/2023] [Indexed: 10/24/2023]
Abstract
PURPOSE To propose an algorithm to facilitate lens-based surgery in keratoconus. METHODS A literature review was performed to prepare a software algorithm based on cone location, stability, best spectacle-corrected distance visual acuity (BSCVA) level and whether there is a clear or cataractous lens. The software usability was assessed through a 10-question questionnaire and two hypothetical keratoconus case histories (moderately simple and moderately complex) given to 15 trainees. The usability questionnaires were graded on a Likert scale (1 = strongly disagree to 5 = strongly agree) and two case histories (1 = very difficult to 7 = very easy). RESULTS The algorithm can be found at https://www.sussexeyelaserclinic.co.uk/keratoconus/. Thirteen trainees completed the questionnaire. 91.9% would frequently use it; for 100%, it was easy to use independently without technical support; for 63.7%, it was strongly integrated; for 100%, it was consistent; 100% thought that most people would learn to use it quickly, 91.9% found the system not cumbersome to use, felt very confident to use it and need not learn a lot to use it. The first case was found easy by 63.7% and the second by 45%. CONCLUSION We present an algorithm as a guide for lens-based surgery in stable and progressing keratoconus, which is classified based on cone location. This algorithm will help trainee and "non-specialist" ophthalmic surgeons understand the pre-operative planning for the surgery and referral to the "specialist" corneal surgeon, considering factors such as progression, BSCVA, keratometry, topography and apex location of the cone in keratoconus patients.
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Affiliation(s)
- Mayank A Nanavaty
- Sussex Eye Hospital, Brighton & Sussex University Hospitals NHS Trust, Brighton, United Kingdom
- Brighton & Sussex Medical School, University of Sussex, Falmer, Brighton, United Kingdom
| | - Zahra Ashena
- Sussex Eye Hospital, Brighton & Sussex University Hospitals NHS Trust, Brighton, United Kingdom
| | - Ingrid Bekono-Nessah
- Brighton & Sussex Medical School, University of Sussex, Falmer, Brighton, United Kingdom
| | - Jennie Harding
- Department of Business Computing, University of Brighton, Brighton, United Kingdom
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Khan M, Ageed A. Advances in the Treatment of Keratoconus: Epithelial-On (EPI-On) Corneal-Collagen Cross-Linking (CXL) and CXL-Plus Procedures. Cureus 2024; 16:e51565. [PMID: 38173952 PMCID: PMC10762651 DOI: 10.7759/cureus.51565] [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] [Accepted: 01/02/2024] [Indexed: 01/05/2024] Open
Abstract
Keratoconus (KC) incidence is on the increase. The advent of corneal-collagen cross-linking (CXL) has revolutionized the management of KC. This systematic review looks at the efficacy and complications of two novel treatments within CXL: Epithelial-On (Epi-On) and CXL-plus procedures. Two separate literature searches were carried out up until July 1, 2021. Articles only published in the last two years were included to ensure that only the most recent articles were reviewed. A total of 15 articles were selected for this review. There were varied results regarding the efficacy of Epi-On. No significant difference was found between Epi-On and standard Epithelial-Off (Epi-Off) CXL. However, it was found that Epi-On was inferior to standard CXL in terms of reducing KMAX. There was a higher risk of progression in patients treated with Epi-On CXL, with an increased rate of patients requiring re-treatment due to the advancement of their KC. While some studies report CXL-plus procedures demonstrate long-term efficacy and safety, a considerable number of studies advise caution, reporting a significant deterioration in corrected distance visual acuity (CDVA). Consequently, a question persists regarding the safest and most efficacious approach, given the lack of robust large randomized controlled trials (RCTs) in the current literature.
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Affiliation(s)
- Maaz Khan
- Medical Education, Royal Surrey County Hospital, Guildford, GBR
| | - Ahmed Ageed
- Internal Medicine, University Hospitals of Leicester NHS Trust, Leicester, GBR
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Oliverio GW, Vagge A, Gargano R, Aragona P, Roszkowska AM. Clinical Results of Accelerated Iontophoresis-Assisted Epithelium-on Corneal Cross-linking for Progressive Keratoconus in Children. J Pediatr Ophthalmol Strabismus 2024; 61:44-50. [PMID: 37227009 DOI: 10.3928/01913913-20230421-01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
PURPOSE To evaluate the clinical characteristics of pediatric patients with progression of keratoconus after accelerated iontophoresis-assisted epithelium-on corneal cross-linking (I-ON CXL) and to assess the efficacy and safety of re-treatment using accelerated epithelium-off CXL (epi-OFF CXL). METHODS Sixteen eyes of 16 patients (mean age: 14.6 ± 2.5 years) with keratoconus underwent I-ON CXL. The main outcome measures were uncorrected distance visual acuity, corrected distance visual acuity, maximum keratometry index (Kmax), minimum corneal thickness, elevation front and elevation back measured at the thinnest point, total higher order aberrations root main square (HOA RMS), coma RMS, and spherical aberration. An increment of Kmax greater than 1.00 diopter (D) and a decrease of greater than 20 µm in pachymetry were considered to determine the progression of keratoconus. Patients with progression of keratoconus after I-ON CXL were re-treated using an epi-OFF CXL protocol. RESULTS Two years after I-ON CXL, 12 patients showed progression of keratoconus, whereas 4 patients were stable. There was significant worsening of Kmax (P = .04) and steepest keratometric reading (P = .01). Furthermore, a significant correlation was documented between progression of keratoconus and age (P = .02). These patients were re-treated using an epi-OFF protocol and after 2 years all patients were stable, and a statistically significant reduction of the mean Kmax (P = .007), HOA RMS (P = .05), and coma RMS (P = 05) was observed. CONCLUSIONS I-ON CXL was ineffective in the treatment of pediatric keratoconus in younger children, whereas it had an efficacy of 2 years in older children. Re-treatment using epi-OFF CXL proved effective to halt progression of keratoconus after I-ON CXL failure. [J Pediatr Ophthalmol Strabismus. 2024;61(1):44-50.].
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Roszkowska AM, Oliverio GW, Hydzik-Sajak K, De Crescenzo M, Aragona P. Five-year results of iontophoresis-assisted transepithelial corneal cross-linking for keratoconus. Int Ophthalmol 2023; 43:3601-3607. [PMID: 37395906 PMCID: PMC10504154 DOI: 10.1007/s10792-023-02768-1] [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: 01/29/2023] [Accepted: 06/19/2023] [Indexed: 07/04/2023]
Abstract
PURPOSE To assess long-term efficacy and safety of iontophoresis-assisted transepithelial corneal cross-linking (I-CXL) for keratoconus. PATIENTS AND METHODS Twenty-seven eyes of 21 patients (15 M, 6F) affected by progressive keratoconus were evaluated. All subjects were treated with iontophoresis-assisted transepithelial CXL. The patients were examined at baseline and each 6 months after the CXL procedure. Only subjects who completed the follow-up of 5 years were considered in this study. The main outcome measures were uncorrected visual acuity (UCVA), corrected visual acuity (CDVA), corneal transparency and corneal parameters such as K-max, central corneal thickness (CCT) and at the thinnest point, and high-order ocular aberrations (HOAs). The ABCD system was used to determine the progression and re-progression of ectasia. SETTING Ophthalmology Clinic, University Hospital of Messina, Messina, Italy. RESULTS At 5 years, significant improvements of UCVA from 0.53 ± 0.33 logMAR to 0.4 ± 0.33 logMAR (p = 0.001) and HOAs (p = 0.01) were registered. No significant changes of CDVA (p = 0.4), K-max (p = 0.75), CCT (p = 0.5) were observed at the end of follow-up period. The ABCD system showed re-progression in 25.9% of eyes after 5 years. No adverse events such as corneal opacities and infections were reported. CONCLUSIONS Iontophoresis-assisted transepithelial CXL resulted to be safe and effective to stabilize progressive keratoconus in adults at a long-term follow-up.
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Affiliation(s)
- Anna Maria Roszkowska
- Ophthalmology Clinic, Department of Biomedical Sciences, University of Messina, Messina, Italy.
- Ophthalmology Clinic, Faculty of Medicine and Health Sciences, Andrzej Frycz Modrzewski Kraków University, Kraków, Poland.
| | | | - Katarzyna Hydzik-Sajak
- Ophthalmology Clinic, Faculty of Medicine and Health Sciences, Andrzej Frycz Modrzewski Kraków University, Kraków, Poland
| | - Michele De Crescenzo
- Ophthalmology Clinic, Department of Biomedical Sciences, University of Messina, Messina, Italy
| | - Pasquale Aragona
- Ophthalmology Clinic, Department of Biomedical Sciences, University of Messina, Messina, Italy
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Gustafsson I, Ivarsen A, Hjortdal J. Early findings in a prospective randomised study on three cross-linking treatment protocols: interruption of the iontophoresis treatment protocol. BMJ Open Ophthalmol 2023; 8:e001406. [PMID: 37739426 PMCID: PMC10533787 DOI: 10.1136/bmjophth-2023-001406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Accepted: 09/03/2023] [Indexed: 09/24/2023] Open
Abstract
PURPOSE To present the outcome of the interrupted iontophoresis-assisted treatment arm in an ongoing randomised clinical trial (NCT04427956). METHODS A randomised clinical study of corneal cross-linking (CXL) using continuous UV-A irradiation at a rate of 9 mW/cm2 and three different types of riboflavin and riboflavin delivery mode: (1) iso-osmolar dextran-based riboflavin (epithelium-off), (2) hypo-osmolar dextran-free riboflavin (epithelium-off) and (3) iontophoresis-assisted delivery of riboflavin (epithelium-on) for the treatment of progressive keratoconus. Inclusion criteria were an increase in the maximum keratometry value (Kmax) of 1.0 dioptre over 12 months or 0.5 dioptre over 6 months. The primary outcome in evaluating treatment efficacy was Kmax. Recently presented stratified detection limits were used post hoc to confirm the enrolment of patients with truly progressive keratoconus and in the assessment of the need for re-CXL. RESULTS Thirteen patients had been randomised to iontophoresis-assisted CXL when the treatment arm was interrupted; two patients dropped out. Of the remaining 11 patients, 7 were deemed as having truly progressive disease according to the more recent stratified detection limits. The disease continued to progress in three patients according to the original definition (increase in Kmax≥1 D), necessitating re-CXL with epithelium-off CXL. This progression was confirmed by post hoc analysis using the stratified detection limits for progression. CONCLUSIONS The iontophoresis-assisted CXL protocol failed to halt further disease progression in 27% of the patients. The failure rate increased to 38% when considering only the patients deemed to have truly progressive disease using the stratified detection limits.
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Affiliation(s)
- Ingemar Gustafsson
- Ophthalmology, Lund University, Lund, Sweden
- Ophthalmology, Skåne University Hospital Lund, Lund, Sweden
| | - Anders Ivarsen
- Ophthalmology, Aarhus University Hospital, Aarhus N, Denmark
| | - Jesper Hjortdal
- Ophthalmology, Aarhus University Hospital, Aarhus N, Denmark
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Liu Y, Shen D, Wang HY, Qi MY, Zeng QY. Development and validation to predict visual acuity and keratometry two years after corneal crosslinking with progressive keratoconus by machine learning. Front Med (Lausanne) 2023; 10:1146529. [PMID: 37534322 PMCID: PMC10393251 DOI: 10.3389/fmed.2023.1146529] [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: 01/17/2023] [Accepted: 06/16/2023] [Indexed: 08/04/2023] Open
Abstract
Purpose To explore and validate the utility of machine learning (ML) methods using a limited sample size to predict changes in visual acuity and keratometry 2 years following corneal crosslinking (CXL) for progressive keratoconus. Methods The study included all consecutive patients with progressive keratoconus who underwent CXL from July 2014 to December 2020, with a 2 year follow-up period before July 2022 to develop the model. Variables collected included patient demographics, visual acuity, spherical equivalence, and Pentacam parameters. Available case data were divided into training and testing data sets. Three ML models were evaluated based on their performance in predicting case corrected distance visual acuity (CDVA) and maximum keratometry (Kmax) changes compared to actual values, as indicated by average root mean squared error (RMSE) and R-squared (R2) values. Patients followed from July 2022 to December 2022 were included in the validation set. Results A total of 277 eyes from 195 patients were included in training and testing sets and 43 eyes from 35 patients were included in the validation set. The baseline CDVA (26.7%) and the ratio of steep keratometry to flat keratometry (K2/K1; 13.8%) were closely associated with case CDVA changes. The baseline ratio of Kmax to mean keratometry (Kmax/Kmean; 20.9%) was closely associated with case Kmax changes. Using these metrics, the best-performing ML model was XGBoost, which produced predicted values closest to the actual values for both CDVA and Kmax changes in testing set (R2 = 0.9993 and 0.9888) and validation set (R2 = 0.8956 and 0.8382). Conclusion Application of a ML approach using XGBoost, and incorporation of identifiable parameters, considerably improved variation prediction accuracy of both CDVA and Kmax 2 years after CXL for treatment of progressive keratoconus.
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Affiliation(s)
- Yu Liu
- Aier School of Ophthalmology, Central South University, Changsha, China
- Aier Eye Hospital of Wuhan University, Wuhan, China
| | - Dan Shen
- Aier Eye Hospital of Wuhan University, Wuhan, China
| | - Hao-yu Wang
- Aier Eye Hospital of Wuhan University, Wuhan, China
| | - Meng-ying Qi
- Aier Eye Hospital of Wuhan University, Wuhan, China
| | - Qing-yan Zeng
- Aier School of Ophthalmology, Central South University, Changsha, China
- Aier Eye Hospital of Wuhan University, Wuhan, China
- Aier Cornea Institute, Beijing, China
- Aier School of Ophthalmology and Optometry, Hubei University of Science and Technology, Xianning, China
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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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Roszkowska AM, Lombardo G, Mencucci R, Scorcia V, Giannaccare G, Vestri A, Alunni Fegatelli D, Bernava GM, Serrao S, Lombardo M. A randomized clinical trial assessing theranostic-guided corneal cross-linking for treating keratoconus: the ARGO protocol. Int Ophthalmol 2022:10.1007/s10792-022-02628-4. [PMID: 36587174 DOI: 10.1007/s10792-022-02628-4] [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: 10/15/2022] [Accepted: 12/20/2022] [Indexed: 01/01/2023]
Abstract
The Assessment of theranostic guided riboflavin/UV-A corneal cross-linking for treatment of keratoconus (ARGO; registration number NCT05457647) clinical trial tests the hypothesis that theranostic-guided riboflavin/UV-A corneal cross-linking (CXL) can provide predictable clinical efficacy for halting keratoconus progression, regardless of treatment protocol, i.e., either with or without epithelial removal. Theranostics is an emerging therapeutic paradigm of personalized and precision medicine that enables real-time monitoring of image-guided therapy. In this trial, the theranostic software module of a novel UV-A medical device will be validated in order to confirm its accuracy in estimating corneal cross-linking efficacy in real time. During CXL procedure, the theranostic UV-A medical device will provide the operator with an imaging biomarker, i.e., the theranostic score, which is calculated by non-invasive measurement of corneal riboflavin concentration and its UV-A light mediated photo-degradation. ARGO is a randomized multicenter clinical trial in patients aged between 18 and 40 years with progressive keratoconus aiming to validate the theranostic score by assessing the change of the maximum keratometry point value at 1-year postoperatively. A total of 50 participants will be stratified with allocation ratio 1:1 using a computer-generated stratification plan with blocks in two treatment protocols, such as epithelium-off or epithelium-on CXL. Following treatment, participants will be monitored for 12 months. Assessment of safety and performance of theranostic-guided corneal cross-linking treatment modality will be determined objectively by corneal tomography, corneal endothelial microscopy, visual acuity testing and slit-lamp eye examination.
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Affiliation(s)
- Anna Maria Roszkowska
- Ophthalmology Department, Faculty of Medicine, Health Sciences of Andrzej Frycz Modrzewski Krakow University, Gustawa Herlinga-Grudzińskiego 1, 30-705, Krakow, Poland. .,Dipartimento BIOMORF, Università di Messina, Via Consolare Valeria 1, 98100, Messina, Italy.
| | - Giuseppe Lombardo
- CNR-IPCF, Istituto per I Processi Chimico-Fisici, Viale F. Stagno D'Alcontres 37, 98158, Messina, Italy
| | - Rita Mencucci
- SOD Oculistica, AOU Careggi, Università di Firenze, Largo Brambilla 3, 50134, Florence, Italy
| | - Vincenzo Scorcia
- UO Oculistica, AOU Mater Domini, Università Magna Graecia di Catanzaro, Viale Europa, 88100, Catanzaro, Italy
| | - Giuseppe Giannaccare
- UO Oculistica, AOU Mater Domini, Università Magna Graecia di Catanzaro, Viale Europa, 88100, Catanzaro, Italy
| | - Annarita Vestri
- Dipartimento di Sanità Pubblica e Malattie Infettive, Università di Roma "La Sapienza", Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Danilo Alunni Fegatelli
- Dipartimento di Sanità Pubblica e Malattie Infettive, Università di Roma "La Sapienza", Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Giuseppe Massimo Bernava
- CNR-IPCF, Istituto per I Processi Chimico-Fisici, Viale F. Stagno D'Alcontres 37, 98158, Messina, Italy
| | | | - Marco Lombardo
- Studio Italiano di Oftalmologia, Via Livenza 3, 00198, Rome, Italy
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Somohano K, Alzaga-Fernandez AG. Controversies in Corneal Collagen Crosslinking: A Review of Investigational Crosslinking Protocols and Its Off-label Application. Int Ophthalmol Clin 2022; 62:51-62. [PMID: 36170222 DOI: 10.1097/iio.0000000000000426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Angelo L, Gokul Boptom A, McGhee C, Ziaei M. Corneal Crosslinking: Present and Future. Asia Pac J Ophthalmol (Phila) 2022; 11:441-452. [PMID: 36094381 DOI: 10.1097/apo.0000000000000557] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Accepted: 07/08/2022] [Indexed: 11/25/2022] Open
Abstract
Keratoconus is a progressive corneal thinning disorder that can lead to vision loss. In the last 2 decades, corneal crosslinking (CXL) has emerged as an effective method to halt the progression of keratoconus and reduce the number of patients requiring keratoplasty. The procedure has been adopted globally and has evolved to become a part of combination treatments to regularize the cornea and improve visual outcomes. CXL has even been extrapolated in managing other ocular pathologies such as progressive myopia, infectious keratitis, and bullous keratopathy. This review aims to summarize the current role of CXL in keratoconus and its alternative uses, and provide insights into future developments in this fast-developing field.
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Affiliation(s)
- Lize Angelo
- Department of Ophthalmology, New Zealand National Eye Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
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Brekelmans J, Dickman MM, Verma S, Arba‐Mosquera S, Goldschmidt R, Goz A, Brandis A, Berendschot TT, Saelens IE, Marcovich AL, Scherz A, Nuijts RM. Excimer laser-assisted corneal epithelial pattern ablation for corneal cross-linking. Acta Ophthalmol 2022; 100:422-430. [PMID: 34533277 PMCID: PMC9291225 DOI: 10.1111/aos.15021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 07/31/2021] [Accepted: 08/31/2021] [Indexed: 11/29/2022]
Abstract
Purpose To determine corneal cross‐linking (CXL) efficacy and chromophore penetration after excimer laser‐assisted patterned de‐epithelialization. Methods Two‐hundred‐twenty porcine eyes were de‐epithelialized ex vivo, either fully (mechanical; n = 88) or patterned (excimer laser; n = 132). Consecutively, corneas were impregnated with hypo‐ or hyperosmolar riboflavin (RF; n = 20, RF‐D; n = 40, respectively) or water‐soluble taurine (WST11; n = 40, and WST‐D; n = 40, respectively), or kept unimpregnated (n = 80). Sixty corneas were subsequently irradiated, inducing CXL, with paired contralateral eyes serving as controls. Outcome measurements included strip extensiometry to assess CXL efficacy, and spectrophotometry and fluorescence microscopy to determine stromal chromophore penetration. Results All tested chromophores induced significant CXL (p < 0.001), ranging from 7.6% to 14.6%, with similar stiffening for all formulations (p = 0.60) and both de‐epithelialization methods (p = 0.56). Light transmittance was significantly lower (p < 0.001) after full compared with patterned de‐epithelialization. Stromal chromophore penetration was comparable between fully and patterned de‐epithelialized samples, with full penetration in RD and RF‐D samples and penetration depths measuring 591.7 ± 42.8 µm and 592.9 ± 63.5 µm for WST11 (p = 0.963) and 504.2 ± 43.2 µm and 488.8 ± 93.1 µm for WST‐D (p = 0.669), respectively. Conclusions Excimer laser‐assisted patterned de‐epithelialization allows for effective CXL. Stromal chromophore concentration is, however, reduced, which may have safety implications given the need for sufficient UVA attenuation in RF/UVA CXL. The different safety profile of near‐infrared (NIR) may allow safe WST11/NIR CXL even with reduced stromal chromophore concentration values. In vivo studies are needed to evaluate the benefits and further assess safety of excimer laser‐assisted patterned de‐epithelialization for corneal CXL.
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Affiliation(s)
- Jurriaan Brekelmans
- University Eye Clinic Maastricht Maastricht University Medical Center Maastricht the Netherlands
- Department of Plant Science and Environmental Health the Weizmann Institute of Science Rehovot Israel
| | - Mor M. Dickman
- University Eye Clinic Maastricht Maastricht University Medical Center Maastricht the Netherlands
| | - Shwetabh Verma
- Department of Research and Development SCHWIND Eye‐Tech‐Solutions Kleinostheim Germany
- Experimental Radiation Oncology University Medical Center Mannheim Heidelberg Germany
- Interdisciplinary Center for Scientific Computing (IWR) Heidelberg University Heidelberg Germany
- Central Institute for Computer Engineering (ZITI) Heidelberg University Heidelberg Germany
| | - Samuel Arba‐Mosquera
- Department of Research and Development SCHWIND Eye‐Tech‐Solutions Kleinostheim Germany
| | - Ruth Goldschmidt
- Department of Plant Science and Environmental Health the Weizmann Institute of Science Rehovot Israel
| | - Alexandra Goz
- Department of Plant Science and Environmental Health the Weizmann Institute of Science Rehovot Israel
- Department of Ophthalmology Kaplan Medical Center Rehovot Israel
| | - Alexander Brandis
- Department of Biological Services the Weizmann Institute of Science Rehovot Israel
| | - Tos T.J.M. Berendschot
- University Eye Clinic Maastricht Maastricht University Medical Center Maastricht the Netherlands
| | - Isabelle E.Y. Saelens
- University Eye Clinic Maastricht Maastricht University Medical Center Maastricht the Netherlands
| | - Arie L. Marcovich
- Department of Plant Science and Environmental Health the Weizmann Institute of Science Rehovot Israel
- Department of Ophthalmology Kaplan Medical Center Rehovot Israel
| | - Avigdor Scherz
- Department of Plant Science and Environmental Health the Weizmann Institute of Science Rehovot Israel
| | - Rudy M.M.A. Nuijts
- University Eye Clinic Maastricht Maastricht University Medical Center Maastricht the Netherlands
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D'Oria F, Alio JL. Are the epi-on and epi-off CXL protocols equivalent in the treatment of keratoconus? ARCHIVOS DE LA SOCIEDAD ESPANOLA DE OFTALMOLOGIA 2022; 97:121-123. [PMID: 35248392 DOI: 10.1016/j.oftale.2022.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 10/19/2021] [Indexed: 06/14/2023]
Affiliation(s)
- F D'Oria
- Vissum Miranza, Alicante, Spain; Department of Basic Medical Science, Neuroscience and Sense Organs, Universidad de Bari, Bari, Italy
| | - J L Alio
- Vissum Miranza, Alicante, Spain; División de Oftalmología, Universidad Miguel Hernández, Alicante, Spain.
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Bhattacharyya A, Sarma P, Kaur H, Hafezi F, Bhattacharyya J, Kirubakaran R, Prajapat M, Medhi B, Das K, Prakash A, Singh A, Kumar S, Singh R, Reddy D, Kaur G, Sharma S. Short- and long-term safety and efficacy of corneal collagen cross-linking in progressive keratoconus: A systematic review and meta-analysis of randomized controlled trials. Taiwan J Ophthalmol 2022. [PMID: 37484615 PMCID: PMC10361434 DOI: 10.4103/2211-5056.361974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
PURPOSE The purpose of the study is to evaluate the safety and outcomes of corneal collagen cross-linking (CXL) and different CXL protocols in progressive keratoconus (PK) population at short and long-term. MATERIALS AND METHODS A systematic review and meta-analysis was conducted. A total of eight literature databases were searched (up to February 15, 2022). Randomized controlled trials (RCTs) comparing CXL versus placebo/control or comparing different CXL protocols in the PK population were included. The primary objective was assessment of outcomes of CXL versus placebo and comparison of different CXL protocols in terms of maximum keratometry (Kmax) or Kmax change from baseline (Δ), spherical equivalent, best corrected visual acuity (BCVA), and central corneal thickness (CCT) in both at short term (6 months) and long term (1st, 2nd, and 3rd year or more). The secondary objective was comparative evaluation of safety. For the meta-analysis, the RevMan5.3 software was used. RESULTS A total of 48 RCTs were included. Compared to control, CXL was associated with improvement in Δ Kmax at 1 year (4 RCTs, mean difference [MD], -1.78 [-2.71, -0.86], P = 0.0002) and 2 and 3 years (1 RCT); ΔBCVA at 1 year (7 RCTs, -0.10 [-0.14, -0.06], P < 0.00001); and Δ CCT at 1 year (2 RCTs) and 3 years (1 RCT). Compared to conventional CXL (C-CXL), deterioration in Δ Kmax, ΔBCVA and endothelial cell density was seen at long term in the transepithelial CXL (TE-CXL, chemical enhancer). Up to 2 years, there was no difference between TE-CXL using iontophoresis (T-ionto) and C-CXL. At 2 and 4 years, C-CXL performed better compared to accelerated CXL (A-CXL) in terms of improving Kmax. Although CCT was higher in the A-CXL arm at 2 years, there was no difference at 4 years. While exploring heterogeneity among studies, selection of control eye (fellow eye of the same patient vs. eye of different patient) and baseline difference in Kmax were important sources of heterogeneity. CONCLUSION CXL outperforms placebo/control in terms of enhancing Kmax and CCT, as well as slowing disease progression over time (till 3 years). T-ionto protocol, on the other hand, performed similarly to C-CXL protocol up to 2 years.
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Preliminary Characterization of Predictive Factors of the Visual Change after Epi-On and Epi-Off Corneal Collagen Crosslinking Techniques. J Ophthalmol 2021; 2021:9680253. [PMID: 34917415 PMCID: PMC8670975 DOI: 10.1155/2021/9680253] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 11/04/2021] [Accepted: 11/24/2021] [Indexed: 11/17/2022] Open
Abstract
Purpose To investigate the potential predictive factors of the visual change achieved with accelerated epi-on and epi-off corneal collagen crosslinking (CXL) in keratoconus. Methods This retrospective comparative study analyzed 67 eyes treated with an accelerated epithelium-on (epi-on group) and epithelium-off (epi-off group) CXL. The clinical outcomes were evaluated and compared during a 1-year follow-up. Likewise, the relationship of the change achieved with both CXL techniques in the corrected distance visual acuity (CDVA) with different preoperative data was investigated. Results The mean CDVA change at 3 months postoperatively was −0.04 ± 0.19 and −0.07 ± 0.25 in the epi-on and epi-off groups, respectively (p = 0.809). In the epi-on group, this change was significantly correlated with the preoperative apical (r = −0.375, p = 0.045) and central corneal thickness (r = −0.402, p = 0.031). In the epi-off group, the CDVA change was significantly correlated with not only the preoperative apical (r = 0.402, p = 0.028) and central corneal thickness (r = 0.367, p = 0.046) but also with some topometric and aberrometric indices (r ≤ −0.374, p ≤ 0.042). Furthermore, the change in CDVA in the epi-on group could be predicted from age, preoperative refractive astigmatism J45 component, anterior corneal asphericity, and posterior corneal high order aberration root mean square (p = 0.002, R2 = 0.503). In the epi-off group, the CDVA change could be predicted from the preoperative minimum corneal thickness and magnitude of the vertical anterior corneal primary coma component (p = 0.001, R2 = 0.446). Conclusions Clearly, different predictive factors of the visual change induced with the accelerated epi-on and epi-off CXL techniques are present, suggesting a different mechanism of action for stiffening the cornea and inducing changes in this structure.
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Transepithelial Diluted Alcohol and Iontophoresis-Assisted Corneal Crosslinking for Progressive Keratoconus in Adults: 4-Year Clinical Results. Cornea 2021; 41:462-469. [PMID: 34743098 DOI: 10.1097/ico.0000000000002821] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 05/29/2021] [Indexed: 11/25/2022]
Abstract
PURPOSE The aim of this study was to compare the 4-year clinical outcomes of transepithelial diluted alcohol and iontophoresis-assisted corneal crosslinking (DAI-CXL) and standard corneal crosslinking (S-CXL) in adults with progressive keratoconus. METHODS This retrospective study included 36 eyes of 36 keratoconic patients who underwent DAI-CXL (n = 18) or S-CXL (n = 18). Best spectacle-corrected visual acuity (BSCVA) and corneal topography parameters were analyzed at baseline and at 1, 2, 3, and 4 years of follow-up. Corneal demarcation line depth (DLD) at 1 month was measured, and the relation of DLD with corneal thickness (DL%) was assessed. RESULTS BSCVA improved significantly only in S-CXL (P = 0.01). A significant decrease in maximum keratometry and mean keratometry occurred at 4 years in both groups (all P < 0.05), and these changes were similar in both groups (all P > 0.05). There was a significant reduction in the thinnest corneal thickness in S-CXL (P = 0.01); however, the mean thinnest corneal thickness in DAI-CXL remained stable (P = 0.094). Higher-order aberrations and coma aberration decreased significantly in both groups at 4 years (all P < 0.05), with a higher decrease in S-CXL (all P < 0.05). Spherical aberration showed a significant reduction only in S-CXL (P = 0.005). In contrast to the similar mean DLD in both groups, DL% in DAI-CXL was significantly greater than that in S-CXL (P = 0.032). There were no correlations between the improvement in BSCVA, maximum keratometry, mean keratometry, higher-order aberrations, and the mean DLD and DL% (all P > 0.05). CONCLUSIONS DAI-CXL was as effective as S-CXL in arresting the progression of keratoconus and showed similar clinical results to S-CXL at the 4-year follow-up.
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Borroni D, Bonzano C, Hristova R, Sánchez González JM, Pennisi F, Rocha-Bogas A, Rocha de Lossada C. A New Surgical Technique to Deliver Riboflavin Beneath Corneal Epithelium: The Corneal Cross-Linking Epi-Pocket. Asia Pac J Ophthalmol (Phila) 2021; 10:495-498. [PMID: 34524144 DOI: 10.1097/apo.0000000000000420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
PURPOSE To describe a new technique to deliver riboflavin into the corneal stroma during Corneal Cross-Linking (CXL) without the removal of corneal epithelium. METHODS Keratoconus patients underwent CXL for progressive keratoconus. Riboflavin was delivered by manually creating an epithelial pocket (CXL Epi-Pocket). Verbal rating scale was recorded postoperatively. Best-corrected visual acuity, keratometric indices, corneal thickness and corneal densitometry were recorded at baseline and at 12-month follow-up. RESULTS Eighteen eyes of 18 patients were included in the study. At a 12-month follow-up, best-corrected visual acuity, K1, K2 and densitometry values were stable. Maximum keratometry (Kmax) reduced from 55.31 ± 6.21 (SD) to 52.34d ± 4.12d (SD) (P value = 0.032). the thinnest point went from 441 ± 21.18 (SD) to 425.4 ± 19.02 (SD) um (P value = 0.041). The verbal rating scale at 1, 2 and 3 days postoperatively were 1.76 ± 0.19 (SD), 1.02 ± 0.51 (SD) and 0.28 ± 0.14 (SD). CONCLUSIONS CXL Epi-Pocket is able to deliver riboflavin to halt the progression of keratoconus at a 12-month follow-up.
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Affiliation(s)
- Davide Borroni
- The Veneto Eye Bank Foundation, Venice, Italy
- Department of Doctoral Studies, Riga Stradins University, Riga, Latvia
| | - Chiara Bonzano
- DiNOGMI, University of Genoa and IRCCS San Martino Polyclinic Hospital, Genoa, Italy
| | - Rozaliya Hristova
- University Hospital Aleksandrovska, Medical University of Sofia, Sofia, Bulgaria
| | - José María Sánchez González
- Department of Physics of Condensed Matter. University of Seville, Seville, Spain
- Department of Ophthalmology (Tecnolaser Clinic Vision ®), Seville, Spain
| | - Flavia Pennisi
- University Vita-Salute, IRCCS Ospedale San Raffaele, Milan, Italy
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Ng SM, Hawkins BS, Kuo IC. Transepithelial Versus Epithelium-Off Corneal Crosslinking for Progressive Keratoconus: Findings From a Cochrane Systematic Review. Am J Ophthalmol 2021; 229:274-287. [PMID: 34048801 PMCID: PMC8599612 DOI: 10.1016/j.ajo.2021.05.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 05/11/2021] [Accepted: 05/15/2021] [Indexed: 11/29/2022]
Abstract
PURPOSE The purpose of this study was to summarize key findings from a systematic review of the effectiveness and safety of transepithelial corneal crosslinking (CXL) compared with epithelium-off CXL for progressive keratoconus. DESIGN Cochrane systematic review. METHODS We included in our review only randomized controlled trials (RCTs) in which transepithelial and epithelium-off CXL had been compared among participants with progressive keratoconus. The primary outcome was keratoconus stabilization based on post-operative maximum keratometry (Kmax). We adhered to Cochrane methods for trial selection, data extraction, risk of bias evaluation, and data synthesis. RESULTS Thirteen RCTs with 567 participants (661 eyes) were included; 11 studies compared non-iontophoresis-assisted transepithelial with epithelium-off CXL. Keratoconus stabilization was described as an outcome in 2 studies. The estimated difference in Kmax means (ie, the "mean difference," MD) from meta-analysis of 177 eyes in 5 RCTs indicated that there were no differences between intervention groups in Kmax at 12 months or later (MD: 0.99 diopter [D]; 95% confidence interval: -0.11 to 2.09). Meta-analysis of keratometry and visual acuity outcomes at 12 months or longer after surgery from 2 studies that had compared transepithelial CXL using iontophoresis provided no conclusive evidence of an advantage over epithelium-off CXL. CONCLUSIONS Lack of precision due to small sample sizes, indeterminate risk of bias due to inadequate reporting, and inconsistency in how outcomes were measured and reported among studies make it difficult to state with confidence whether transepithelial CXL confers an advantage over epithelium-off CXL for patients with progressive keratoconus with respect to stabilization of keratoconus, visual acuity, or patient-reported outcomes based on available data.
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Affiliation(s)
- Sueko M Ng
- From the Department of Ophthalmology (S.M.N.), School of Medicine, University of Colorado, Aurora, Colorado, USA
| | - Barbara S Hawkins
- and the Department of Ophthalmology (B.S.H., I.C.K.), Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Irene C Kuo
- and the Department of Ophthalmology (B.S.H., I.C.K.), Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.
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D'Oria F, Palazón A, Alio JL. Corneal collagen cross-linking epithelium-on vs. epithelium-off: a systematic review and meta-analysis. EYE AND VISION (LONDON, ENGLAND) 2021; 8:34. [PMID: 34565473 PMCID: PMC8465763 DOI: 10.1186/s40662-021-00256-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 08/08/2021] [Indexed: 01/08/2023]
Abstract
BACKGROUND The purpose of the study was to determine the advantages and disadvantages of epi-on corneal cross-linking (CXL) techniques compared with standard epi-off CXL. METHODS We searched MEDLINE and EMBASE for randomized controlled trials (RCTs) and non-randomized studies of interventions (NRSIs) and we evaluated the selected papers according to the Cochrane risk of bias tool. We considered, as primary outcomes, average Kmax flattening, changes in uncorrected and corrected distance visual acuity (UDVA and CDVA); as secondary outcomes, we considered changes in pachymetry values and endothelial cell density (ECD). We also investigated adverse events related to the treatments and treatment failure. Meta-analysis was conducted with a fixed or random-effects model using weighted mean difference (MD) with 95% confidence interval (CI) as the effect size. RESULTS A total of 15 studies were included and among these 15 trials, 9 were RCTs and 6 were NRSIs, but only 4 studies showed no high risk of bias and were included in this meta-analysis. Our analysis revealed significant postoperative differences in CDVA (MD = 0.07; 95% CI 0.04 to 0.10; P < 0.001), and no significative differences in UDVA, Kmax, central corneal thickness (CCT) and ECD (P > 0.05). Epi-on CXL protocol was found to be significantly less prompt to have risks of delay in epithelial healing (P = 0.035) and persistent stromal haze (P = 0.026). CONCLUSION Epi-on CXL is as effective as epi-off CXL. Except for a higher significant improvement in CDVA with current epi-on protocols, our meta-analysis demonstrates that epi-on and epi-off CXL have comparable effects on visual, topographic, pachymetric, and endothelial parameters. Epi-on CXL has clinical advantages in terms of comfort and avoidance of complications as it reduces the risk of developing delay in epithelial healing and persistent stromal haze.
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Affiliation(s)
- Francesco D'Oria
- Vissum Innovation, c/ Cabañal, 1, 03016, Alicante, Spain
- Division of Ophthalmology, Universidad Miguel Hernández, Alicante, Spain
- Section of Ophthalmology, Department of Basic Medical Science, Neuroscience and Sense Organs, University of Bari, Bari, Italy
| | - Antonio Palazón
- Department of Clinical Medicine, Miguel Hernández University, San Juan de Alicante, Spain
| | - Jorge L Alio
- Vissum Innovation, c/ Cabañal, 1, 03016, Alicante, Spain.
- Division of Ophthalmology, Universidad Miguel Hernández, Alicante, Spain.
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Adverse events after riboflavin/UV-A corneal cross-linking: a literature review. Int Ophthalmol 2021; 42:337-348. [PMID: 34448966 DOI: 10.1007/s10792-021-02019-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 08/12/2021] [Indexed: 10/20/2022]
Abstract
BACKGROUND Riboflavin/UV-A corneal cross-linking (CXL) for treating keratoconus and iatrogenic corneal ectasia has been well-established as first treatment option to stabilize corneal tissue biomechanical instability. Although the plethora of clinical studies has been published into the field, there is no systematic review assessing the type and frequency of adverse events after CXL. METHODS A systemic literature review on clinical safety and adverse events after CXL in patients with keratoconus and corneal ectasia was performed using PubMed. A literature search was performed for relevant peer-reviewed publications. The main outcome measures extracted from the articles were adverse events, endothelial cell density, corrected distance visual acuity and maximum simulated keratometry. RESULTS The most frequent adverse events after CXL were corneal haze and corneal edema, which were mild and transient. The severe adverse events were infrequent (cumulative incidence: < 1.3%) after CXL. The clinical benefits of CXL highly outweighed the risks for the treatment of keratoconus and corneal ectasia. CONCLUSIONS The severe adverse events with permanent sequelae are infrequent after CXL and all are associated with corneal de-epithelialization, such as infectious keratitis and corneal scarring.
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22
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A histological examination of corneal epithelium after iontophoresis with different riboflavin solutions. Chin Med J (Engl) 2021; 135:753-755. [PMID: 34310398 PMCID: PMC9276224 DOI: 10.1097/cm9.0000000000001579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Indexed: 11/26/2022] Open
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Shetty R, Kundu G, Narasimhan R, Khamar P, Gupta K, Singh N, Nuijts RMMA, Sinha Roy A. Artificial Intelligence Efficiently Identifies Regional Differences in the Progression of Tomographic Parameters of Keratoconic Corneas. J Refract Surg 2021; 37:240-248. [PMID: 34038661 DOI: 10.3928/1081597x-20210120-01] [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: 01/31/2023]
Abstract
PURPOSE To develop an artificial intelligence (AI) model to effectively assess local versus global progression of keratoconus using multiple tomographic parameters. METHODS This was a retrospective review of medical records of patients diagnosed as having keratoconus. A total of 1,884 Pentacam (Oculus Optikgeräte GmbH) scans of 366 eyes (296 patients) were analyzed. Based on an increase in maximum anterior curvature (Kmax), the eyes were classified as actual "progression" and "no progression." The corresponding changes in other Pentacam parameters were incorporated to train and cross-validate (five-fold) the AI models. Three AI models were trained (an increase in Kmax by A = 0.75 diopters [D], B = 1.00 D, and C = 1.25 D). The area under the curve (AUC), sensitivity, specificity, and classification accuracy, along with other metrics, were evaluated. RESULTS The AUC, sensitivity, specificity, and classification accuracy were 0.90, 85%, 82%, and 83%, respectively, for Model A; 0.91, 86%, 82%, and 88%, respectively, for Model B; and 0.93, 89%, 81%, and 91%, respectively, for Model C. All models also predicted that 60% to 62% of the actual progression eyes had concomitant progression-associated changes in the other Pentacam parameters (global progression). However, there was discordance between increase in Kmax and concomitant associated changes in the other parameters in 38.8% to 40% of the eyes (local progression). CONCLUSIONS The AI models identified the eyes where the increase in Kmax and corresponding progression-associated changes in the other parameters were in agreement. These eyes may require corneal cross-linking earlier than the rest. [J Refract Surg. 2021;37(4):240-248.].
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Mazzotta C, Bagaglia SA, Sgheri A, Di Maggio A, Fruschelli M, Romani A, Vinciguerra R, Vinciguerra P, Tosi GM. Iontophoresis Corneal Cross-linking With Enhanced Fluence and Pulsed UV-A Light: 3-Year Clinical Results. J Refract Surg 2021; 36:286-292. [PMID: 32396639 DOI: 10.3928/1081597x-20200406-02] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 03/25/2020] [Indexed: 11/20/2022]
Abstract
PURPOSE To assess 3-year safety and efficacy of enhanced-fluence pulsed-light iontophoresis cross-linking (EF I-CXL) in patients with progressive keratoconus. METHODS This prospective interventional pilot study included 24 eyes of 20 patients, with a mean age of 23.9 years (range: 15 to 36 years). Iontophoresis with riboflavin solution was used for stromal imbibition. The treatment energy was optimized at 30% (7 J/cm2) and ultraviolet-A power set at 18 mW/cm2 × 6.28 minutes of pulsed-light on-off exposure, with a total irradiation time of 12.56 minutes. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), corneal tomography, and corneal optical coherence tomography (OCT) at baseline and 1, 3, 6, 12, 24, and 3 years postoperatively were evaluated. RESULTS At 3 years, average UDVA decreased from 0.50 ± 0.10 to 0.36 ± 0.08 logMAR (P < .05), average maximum keratometry decreased from 52.94 ± 1.34 to 51.4 ± 1.49 diopters (D) (Delta: -1.40 ± 0.80 D; P < .05), average coma improved from 0.24 ± 0.05 to 0.12 ± 0.02 µm (P = .001), and symmetry index decreased from 4.22 ± 1.01 to 3.53 ± 0.90 D. Corneal OCT showed demarcation line detection at 285.8 ± 20.2 µm average depth in more than 80% at 1 month postoperatively. CONCLUSIONS The 3-year results of EF I-CXL showed satisfactory I-CXL functional outcomes, increasing the visibility and the depth of demarcation line closer to epithelium-off standard CXL. [J Refract Surg. 2020;36(5):286-292.].
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Ng SM, Ren M, Lindsley KB, Hawkins BS, Kuo IC. Transepithelial versus epithelium-off corneal crosslinking for progressive keratoconus. Cochrane Database Syst Rev 2021; 3:CD013512. [PMID: 33765359 PMCID: PMC8094622 DOI: 10.1002/14651858.cd013512.pub2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
BACKGROUND Keratoconus is the most common corneal dystrophy. It can cause loss of uncorrected and best-corrected visual acuity through ectasia (thinning) of the central or paracentral cornea, irregular corneal scarring, or corneal perforation. Disease onset usually occurs in the second to fourth decade of life, periods of peak educational attainment or career development. The condition is lifelong and sight-threatening. Corneal collagen crosslinking (CXL) using ultraviolet A (UVA) light applied to the cornea is the only treatment that has been shown to slow progression of disease. The original, more widely known technique involves application of UVA light to de-epithelialized cornea, to which a photosensitizer (riboflavin) is added topically throughout the irradiation process. Transepithelial CXL is a recently advocated alternative to the standard CXL procedure, in that the epithelium is kept intact during CXL. Retention of the epithelium offers the putative advantages of faster healing, less patient discomfort, faster visual rehabilitation, and less risk of corneal haze. OBJECTIVES To assess the short- and long-term effectiveness and safety of transepithelial CXL compared with epithelium-off CXL for progressive keratoconus. SEARCH METHODS To identify potentially eligible studies, we searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2020, Issue 1); Ovid MEDLINE; Embase.com; PubMed; Latin American and Caribbean Health Sciences Literature database (LILACS); ClinicalTrials.gov; and World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). We did not impose any date or language restrictions. We last searched the electronic databases on 15 January 2020. SELECTION CRITERIA We included randomized controlled trials (RCTs) in which transepithelial CXL had been compared with epithelium-off CXL in participants with progressive keratoconus. DATA COLLECTION AND ANALYSIS We used standard Cochrane methodology. MAIN RESULTS We included 13 studies with 723 eyes of 578 participants enrolled; 13 to 119 participants were enrolled per study. Seven studies were conducted in Europe, three in the Middle East, and one each in India, Russia, and Turkey. Seven studies were parallel-group RCTs, one study was an RCT with a paired-eyes design, and five studies were RCTs in which both eyes of some or all participants were assigned to the same intervention. Eleven studies compared transepithelial CXL with epithelium-off CXL in participants with progressive keratoconus. There was no evidence of an important difference between intervention groups in maximum keratometry (denoted 'maximum K' or 'Kmax'; also known as steepest keratometry measurement) at 12 months or later (mean difference (MD) 0.99 diopters (D), 95% CI -0.11 to 2.09; 5 studies; 177 eyes; I2 = 41%; very low certainty evidence). Few studies described other outcomes of interest. The evidence is very uncertain that epithelium-off CXL may have a small (data from two studies were not pooled due to considerable heterogeneity (I2 = 92%)) or no effect on stabilization of progressive keratoconus compared with transepithelial CXL; comparison of the estimated proportions of eyes with decreases or increases of 2 or more diopters in maximum K at 12 months from one study with 61 eyes was RR 0.32 (95% CI 0.09 to 1.12) and RR (non-event) 0.86 (95% CI 0.74 to 1.00), respectively (very low certainty). We did not estimate an overall effect on corrected-distance visual acuity (CDVA) because substantial heterogeneity was detected (I2 = 70%). No study evaluated CDVA gain or loss of 10 or more letters on a logarithm of the minimum angle of resolution (logMAR) chart. Transepithelial CXL may result in little to no difference in CDVA at 12 months or beyond. Four studies reported that either no adverse events or no serious adverse events had been observed. Another study noted no change in endothelial cell count after either procedure. Moderate certainty evidence from 4 studies (221 eyes) found that epithelium-off CXL resulted in a slight increase in corneal haze or scarring when compared to transepithelial CXL (RR (non-event) 1.07, 95% CI 1.01 to 1.14). Three studies, one of which had three arms, compared outcomes among participants assigned to transepithelial CXL using iontophoresis versus those assigned to epithelium-off CXL. No conclusive evidence was found for either keratometry or visual acuity outcomes at 12 months or later after surgery. Low certainty evidence suggests that transepithelial CXL using iontophoresis results in no difference in logMAR CDVA (MD 0.00 letter, 95% CI -0.04 to 0.04; 2 studies; 51 eyes). Only one study examined gain or loss of 10 or more logMAR letters. In terms of adverse events, one case of subepithelial infiltrate was reported after transepithelial CXL with iontophoresis, whereas two cases of faint corneal scars and four cases of permanent haze were observed after epithelium-off CXL. Vogt's striae were found in one eye after each intervention. The certainty of the evidence was low or very low for the outcomes in this comparison due to imprecision of estimates for all outcomes and risk of bias in the studies from which data have been reported. AUTHORS' CONCLUSIONS Because of lack of precision, frequent indeterminate risk of bias due to inadequate reporting, and inconsistency in outcomes measured and reported among studies in this systematic review, it remains unknown whether transepithelial CXL, or any other approach, may confer an advantage over epithelium-off CXL for patients with progressive keratoconus with respect to further progression of keratoconus, visual acuity outcomes, and patient-reported outcomes (PROs). Arrest of the progression of keratoconus should be the primary outcome of interest in future trials of CXL, particularly when comparing the effectiveness of different approaches to CXL. Furthermore, methods of assessing and defining progressive keratoconus should be standardized. Trials with longer follow-up are required in order to assure that outcomes are measured after corneal wound-healing and stabilization of keratoconus. In addition, perioperative, intraoperative, and postoperative care should be standardized to permit meaningful comparisons of CXL methods. Methods to increase penetration of riboflavin through intact epithelium as well as delivery of increased dose of UVA may be needed to improve outcomes. PROs should be measured and reported. The visual significance of adverse outcomes, such as corneal haze, should be assessed and correlated with other outcomes, including PROs.
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Affiliation(s)
- Sueko M Ng
- Department of Ophthalmology, School of Medicine, University of Colorado, Aurora, CO, USA
| | - Mark Ren
- Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Kristina B Lindsley
- Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, Netherlands
| | - Barbara S Hawkins
- Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Irene C Kuo
- Wilmer Eye Institute, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Wan KH, Ip CKY, Kua WN, Chow VWS, Chong KKL, Young AL, Cheng GPM, Jhanji V. Transepithelial corneal collagen cross‐linking using iontophoresis versus the Dresden protocol in progressive keratoconus: A meta‐analysis. Clin Exp Ophthalmol 2021; 49:228-241. [DOI: 10.1111/ceo.13918] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Revised: 02/24/2021] [Accepted: 02/26/2021] [Indexed: 02/01/2023]
Affiliation(s)
- Kelvin H. Wan
- Department of Ophthalmology and Visual Sciences The Chinese University of Hong Kong Kowloon Hong Kong
- Hong Kong Eye Hospital Kowloon Hong Kong
| | - Christina K. Y. Ip
- Department of Ophthalmology and Visual Sciences Prince of Wales Hospital Shatin Hong Kong
| | - Wee Nie Kua
- Department of Ophthalmology Tuen Mun Hospital Tuen Mun Hong Kong
| | - Vanissa W. S. Chow
- Department of Ophthalmology and Visual Sciences The Chinese University of Hong Kong Kowloon Hong Kong
- Hong Kong Eye Hospital Kowloon Hong Kong
| | - Kelvin K. L. Chong
- Department of Ophthalmology and Visual Sciences The Chinese University of Hong Kong Kowloon Hong Kong
- Department of Ophthalmology and Visual Sciences Prince of Wales Hospital Shatin Hong Kong
| | - Alvin L. Young
- Department of Ophthalmology and Visual Sciences The Chinese University of Hong Kong Kowloon Hong Kong
- Department of Ophthalmology and Visual Sciences Prince of Wales Hospital Shatin Hong Kong
| | - George P. M. Cheng
- Department of Ophthalmology and Visual Sciences The Chinese University of Hong Kong Kowloon Hong Kong
- Hong Kong Laser Eye Centre Central Hong Kong
| | - Vishal Jhanji
- Department of Ophthalmology University of Pittsburgh School of Medicine Pittsburgh Pennsylvania USA
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New perspectives in keratoconus treatment: an update on iontophoresis-assisted corneal collagen crosslinking. Int Ophthalmol 2021; 41:1909-1916. [PMID: 33590372 DOI: 10.1007/s10792-021-01713-4] [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] [Received: 09/01/2020] [Accepted: 01/09/2021] [Indexed: 10/22/2022]
Abstract
Keratoconus is a bilateral, asymmetric and progressive corneal disease. It usually results in apical thinning and steepening with corneal deformation and impaired vision. Since the early 1990 s, corneal collagen crosslinking (CXL) has remained the primary treatment to stabilize the progression of the disease. Iontophoresis-assisted CXL (I-CXL) has been proposed as a non-invasive alternative to standard epithelium-off technique, showing promising results. In this article, we review up to date literature to provide state of art knowledge and future perspectives of I-CXL.
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Helmy AM. Overview of recent advancements in the iontophoretic drug delivery to various tissues and organs. J Drug Deliv Sci Technol 2021. [DOI: 10.1016/j.jddst.2021.102332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Comparison of Standard and Transepithelial Corneal Cross-Linking for the Treatment of Keratoconus: A Meta-analysis. J Ophthalmol 2021; 2021:6679770. [PMID: 33575037 PMCID: PMC7864754 DOI: 10.1155/2021/6679770] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 01/03/2021] [Accepted: 01/18/2021] [Indexed: 11/26/2022] Open
Abstract
Purpose To compare the clinical results of standard corneal cross-linking (SCXL) with transepithelial corneal cross-linking (TECXL) in progressive keratoconus using a meta-analysis. Methods PubMed, EMBASE, and Cochrane Central Register of Controlled Trials were searched up to June 2020 to identify relevant studies. The PRISMA guidelines were followed. Primary outcomes were change in uncorrected distance visual acuity and maximum keratometry (Kmax) after CXL. Secondary outcomes were change in corrected distance visual acuity, mean refractive spherical equivalent (MRSE), spherical and cylindrical error, endothelial cells density (ECD), and central corneal thickness (CCT). Results Sixteen studies with a total of 690 eyes (SCXL: 332 eyes; TECXL: 358 eyes) were included. At the last follow-up, SCXL provided a greater decrease in maximum keratometry (Kmax) than TECXL (weighted mean difference (WMD) −1.12; 95% confidence interval (CI) −1.96, −0.29). For the other outcomes, there were no statistically significant differences. Conclusions Except for a greater decrease in Kmax with SCXL group, both groups have a comparable effect on visual, pachymetric, and endothelial parameters at 24 months after surgery. Larger studies with a longer follow-up time are necessary to determine whether these techniques are comparable in the long term.
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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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Nath S, Shen C, Koziarz A, Banfield L, Nowrouzi-Kia B, Fava MA, Hodge WG. Transepithelial versus Epithelium-off Corneal Collagen Cross-linking for Corneal Ectasia: A Systematic Review and Meta-analysis. Ophthalmology 2020; 128:1150-1160. [PMID: 33383093 DOI: 10.1016/j.ophtha.2020.12.023] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 12/11/2020] [Accepted: 12/21/2020] [Indexed: 01/19/2023] Open
Abstract
TOPIC To evaluate the safety and efficacy of transepithelial corneal cross-linking in comparison with the established epithelium-off technique for corneal ectasia. CLINICAL RELEVANCE Considerable debate exists regarding whether transepithelial and epithelium-off cross-linking are comparable in their safety and efficacy. METHODS We searched 16 electronic databases, including Medline, Embase, Web of Science, and the grey literature, current to July 8, 2020, for randomized controlled trials comparing transepithelial and epithelium-off cross-linking for corneal ectasia. We excluded studies evaluating cross-linking for nonectatic indications, as well as non-randomized controlled trials. Our primary outcome was the change in maximal keratometry (Kmax) at 12 months after cross-linking, and we considered additional topographic, visual, and safety outcomes. We summarized our analyses by calculating weighted mean differences (MDs) with associated 95% confidence intervals (CIs) for continuous outcomes and relative risks (RRs) with corresponding 95% CIs for dichotomous outcomes. We conducted trial sequential analysis to determine whether the required information size was met for each outcome. The quality of individual trials was evaluated using the Cochrane Collaboration's risk of bias assessment tool, and the evidence was assessed at an outcome level using the Grading of Recommendations Assessment, Development, and Evaluation methodology. RESULTS Twelve studies totaling 966 eyes were eligible. A significant difference was found between transepithelial and epithelium-off cross-linking groups in the change in Kmax at 12 months (MD, 0.75; 95% CI, 0.23-1.28; P = 0.004; primary outcome) and at longest follow-up (MD, 1.20; 95% CI, 0.62-1.77; P < 0.001; secondary outcome) after treatment. No significant difference was found between the 2 groups when examining uncorrected distance visual acuity (MD, 0.04; 95% CI, -0.06 to 0.14; P = 0.386) or corrected distance visual acuity (MD, 0.01; 95% CI, -0.06 to 0.09; P = 0.732). Transepithelial cross-linking was associated with significantly fewer complications than the epithelium-off approach (RR, 0.22; 95% CI, 0.06-0.79; P = 0.020), although it was associated with an increased rate of disease progression at 12 months after treatment (RR, 4.49; 95% CI, 1.24-16.25; P = 0.022). The required information size was met for our primary outcome and trial sequential analysis supported the conventional meta-analysis. The quality of evidence was rated as moderate using the Grading of Recommendations Assessment, Development, and Evaluation methodology. DISCUSSION The efficacy of transepithelial cross-linking remains inferior to the epithelium-off approach, although it is significantly safer.
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Affiliation(s)
- Siddharth Nath
- Department of Ophthalmology and Visual Sciences, McGill University, Montréal, Canada.
| | - Carl Shen
- Division of Ophthalmology, Department of Surgery, Faculty of Health Sciences, McMaster University, Hamilton, Canada
| | - Alex Koziarz
- Faculty of Medicine, University of Toronto, Toronto, Canada
| | - Laura Banfield
- Health Sciences Library, McMaster University, Hamilton, Canada
| | - Behnam Nowrouzi-Kia
- Michael G. DeGroote School of Medicine, Faculty of Health Sciences, McMaster University, Hamilton, Canada
| | - Mark A Fava
- Division of Ophthalmology, Department of Surgery, Faculty of Health Sciences, McMaster University, Hamilton, Canada
| | - William G Hodge
- Department of Ophthalmology, Ivey Eye Institute, Schulich School of Medicine and Dentistry, Western University, London, Canada; Department of Epidemiology and Biostatistics, Schulich School of Medicine and Dentistry, Western University, London, Canada
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Saad S, Saad R, Jouve L, Kallel S, Trinh L, Goemaere I, Borderie V, Bouheraoua N. Corneal crosslinking in keratoconus management. J Fr Ophtalmol 2020; 43:1078-1095. [DOI: 10.1016/j.jfo.2020.07.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 07/09/2020] [Accepted: 07/30/2020] [Indexed: 01/04/2023]
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Corneal Cross-linking: Epi-On vs. Epi-Off Current Protocols, Pros, and Cons. CURRENT OPHTHALMOLOGY REPORTS 2020. [DOI: 10.1007/s40135-020-00241-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Lombardo G, Serrao S, Lombardo M. Comparison between standard and transepithelial corneal crosslinking using a theranostic UV-A device. Graefes Arch Clin Exp Ophthalmol 2020; 258:829-834. [PMID: 31900647 DOI: 10.1007/s00417-019-04595-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 12/20/2019] [Accepted: 12/27/2019] [Indexed: 02/07/2023] Open
Abstract
PURPOSE To assess corneal concentration of riboflavin in two different corneal crosslinking protocols performed by a novel image-guided therapeutic (or "theranostic") UV-A device. METHODS Ten human eye bank donor tissues were used in this work. The tissues underwent corneal cross-linking according to the conventional treatment protocol (n = 5; 30 min of stromal soaking followed by 30 min of 3 mW/cm2 UV-A irradiance) and the iontophoresis-assisted transepithelial protocol (n = 5; soaking for 5 min at 1 mA/min and 9 min of 10 mW/cm2 UV-A irradiance) using a theranostic UV-A device (Vision Engineering Italy srl, Italy). The device provided real time assessment of riboflavin concentration by hyperspectral image analysis of the cornea. A 0.1% riboflavin hypotonic solution (Ricrolin+, Sooft Italia Spa, Italy) was used in all cases. RESULTS Manual application of hypotonic riboflavin for 30 min into the stroma achieved greater corneal riboflavin concentration (425 ± 77 μg/cm3) than transepithelial delivery of riboflavin by corneal iontophoresis (195 ± 35 μg/cm3; P = 0.001). In both UV-A irradiation protocols, corneal riboflavin concentration decreased exponentially with a constant energy rate of 2.3 ± 0.5 J/cm2 and 1.8 ± 0.3 J/cm2 respectively. At the end of treatment, the average corneal concentration of riboflavin decreased by ≥ 85%, with values of 54 ± 29 μg/cm3 and 31 ± 9 μg/cm3 (P = 0.11), respectively. CONCLUSION Manual application of riboflavin onto the stroma achieved almost 50% greater concentration of riboflavin than transepithelial delivery by corneal iontophoresis. The theranostic UV-A device provided a novel approach to estimate corneal concentration of riboflavin non-invasively during treatment.
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Affiliation(s)
- Giuseppe Lombardo
- Vision Engineering Italy srl, Via Livenza 3, 00198, Rome, Italy.,CNR-IPCF, Istituto per i Processi Chimico-Fisici, Viale F. Stagno D'Alcontres 37, 98158, Messina, Italy
| | | | - Marco Lombardo
- Vision Engineering Italy srl, Via Livenza 3, 00198, Rome, Italy. .,Studio Italiano di Oftalmologia, Via Livenza 3, 00198, Rome, Italy.
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Corneal crosslinking: Current protocols and clinical approach. J Cataract Refract Surg 2019; 45:1670-1679. [DOI: 10.1016/j.jcrs.2019.06.027] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 05/19/2019] [Accepted: 06/21/2019] [Indexed: 12/18/2022]
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