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Purpose: To present baseline characteristics and to present the perioperative corneal thickness during corneal crosslinking (CXL) treatment for progressive keratoconus and to describe how the addition of sterile water (SW) efficaciously can maintain the corneal thickness. The treatment efficacy will be evaluated when the 1‐year follow‐up is complete. Methods: A randomised clinical study using epithelium‐off CXL with continuous UVA irradiation (9 mW/cm2) and two kinds of riboflavin solutions: (i) isoosmolar dextran‐based riboflavin (n = 27) and (ii) hypoosmolar dextran‐free riboflavin (n = 27). Inclusion criteria: progressive keratoconus with an increase in maximum keratometry value (Kmax) of 1.0 dioptre (12 months) or 0.5 dioptres (6 months). Corneae thinner than 400 μm were also included. Outcome parameters: Perioperative corneal thickness and the effect of adding SW. Results: Seventy‐four per cent of the patients in the isoosmolar group and 15% in the hypoosmolar group required the addition of SW, which effectively maintained a corneal thickness of 400 μm in all cases during CXL. The addition of SW was primarily needed during the irradiation procedure and not the preoperative soaking period. Conclusions: Especially during the CXL irradiation phase, isoosmolar riboflavin causes a significant dehydrating effect leading to corneal thinning during CXL. The customised addition of SW is efficacious in maintaining the corneal thickness during CXL and could increase the safety of the procedure. [ABSTRACT FROM AUTHOR]

PurposeTo comprehensively compare the long-term outcome of the combined topography guided photorefractive keratectomy (TG-PRK) with accelerated corneal cross-linking (ACXL) and ACXL alone in eyes with progressive keratoconus. The analysis focused on the changes in the detailed corneal aberrometric values.MethodsThis single-center, prospective cohort study included 28 patients (30 eyes) of the TG-PRK plus ACXL group and 14 patients (15 eyes) of the ACXL alone group. The mean duration of the follow-up was 44 ± 10.18 months (ranged from 31 to 65 months). The preoperative data and the postoperative measurement data at the last follow-up visit, including demographic data, uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refraction, corneal topography, pachymetry, aberrometry and densitometry were analyzed.ResultsThe CDVA significantly improved in the TG-PRK plus ACXL group at the last follow-up visit (p = 0.006), while no significant improvement was found in the ACXL alone group (p = 0.432). The maximal keratometry of the anterior corneal surface (Kmax) of both groups significantly decreased at the last follow-up visit (p

Rodrigo Vilares-Morgado,1,2 Ana Margarida Ferreira,1,2 Ana Maria Cunha,1,2 Raúl Moreira,1,2 Luís Torrão,1,2 Pedro Neves-Cardoso,1,2 João Pinheiro-Costa1– 3 1Department of Ophthalmology, Centro Hospitalar Universitário de São João, Porto, Portugal; 2Department of Surgery and Physiology, Faculty of Medicine of Porto University, Porto, Portugal; 3Department of Biomedicine, Faculty of Medicine of Porto University, Porto, PortugalCorrespondence: Rodrigo Vilares-Morgado, Department of Ophthalmology, Centro Hospitalar Universitário de São João, Alameda Prof. Hernâni Monteiro, Porto, 4202-451, Portugal, Tel +351 914 471 067, Fax +351 225 512 100, Email vilaresmorgador@gmail.comPurpose: To report the 4-year outcomes of transepithelial accelerated corneal collagen crosslinking (TE-ACXL) in the treatment of eyes with progressive keratoconus (KC).Methods: Eyes of patients who underwent TE-ACXL (6mW/cm2 for 15 minutes) for progressive KC and presented 48 months of follow-up were included. Corrected distance visual acuity (CDVA), keratometry measurements (Kmax, maximum keratometry, Kmean, mean keratometry and Astg, corneal astigmatism), thinnest corneal thickness (PachyMin), and topographic, and tomographic indices (specifically the posterior radius of curvature from the 3.0 mm centered on the thinnest point of the cornea (PRC), and the D-index) were analysed preoperatively and every 12 months after TE-ACXL, up to 48 months. Progression after TE-ACXL was considered when eyes presented ≥ 1 criteria: (1) increase of ≥ 1D in Kmax or increase of ≥ 0.75D in Kmean or increase of ≥ 1D in Astg; (2) reduction of ≥ 0.085 mm in PRC; (3) decrease ≥ 5% in PachyMin.Results: 41 eyes from 30 patients were included, with a mean age at crosslinking of 20.90± 4.69 years. There was a significant increase in Kmean (+0.64± 1.04 D, p< 0.001; +0.98 ± 1.49 D, p< 0.001; +1.27± 2.01 D, p< 0.001; +1.13± 2.00 D, p=0.006) and a significant decrease in PRC throughout follow-up (− 0.12± 0.22, p=0.002; − 0.15± 0.24, p< 0.001; − 0.17± 0.43, p=0.021; − 0.16± 0.43, p=0.027). PachyMin decreased significantly at 36 and 48 months (− 8.50± 15.93 μm, p=0.004; − 7.82± 18.37, p=0.033). According to our progression criteria, there was a major progression rate throughout follow-up (57.1%, 61.1%, 58.8%, and 67.9%, respectively). Surgery and follow-up were uneventful in all subjects. Eleven eyes (26.8%) required further procedures, ≥ 36 months after the initial TE-ACXL, due to persistent progressive disease.Conclusion: TE-ACXL proved to be a safe therapeutic option for progressive KC. However, its efficacy is deemed unsatisfactory, as a notable proportion of affected eyes may continue to advance within a 4-year timeframe, necessitating additional procedures to halt the disease’s course.Keywords: progressive keratoconus, trans-epithelial corneal crosslinking, epi-on crosslinking, keratoconus progression

Purpose: To compare the refractive efficacy and morphological changes in the cornea following a novel biphasic higher fluence transepithelial corneal crosslinking (BI-TE-CXL) and transepithelial corneal crosslinking (TE-CXL) in adults keratoconus. Methods: Patients with progressive keratoconus who required corneal crosslinking were assigned to the BI-TE-CXL group (32 eyes, phase 1: 7.2 J/cm2 for 5 min and 20 s of pulsed-light exposure, KXL, Glaukos-Avedro; phase 2: 3.6 J/cm2 for 6 min and 40 s of continuous light exposure at the front curvature apex with a 6 mm diameter light spot, UVX-2000, IROC) or the TE-CXL group (32 eyes, uniform 7.2 J/cm2 for 5 min and 20 s of pulsed-light exposure, KXL, Glaukos-Avedro). Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), corneal fluorescein staining (CFS), corneal topography, anterior segment optical coherence tomography (AS-OCT), and in vivo corneal confocal microscopy (IVCM) were performed 3, 6, 12 and 24 months after surgery. Results: The CFS scores in the BI-TE-CXL group were significantly higher than those in the TE-CXL group on the first two days after surgery (p < 0.001). The Kmax (at 12 and 24 months) and CDVA (logMAR) were significantly lower in the BI-TE-CXL group than those in the TE-CXL group (p < 0.05). The corneal demarcation line under AS-OCT was visible in 81.3% of patients in the BI-TE-CXL group and 15.6% in the TE-CXL group. The depth of the demarcation line under IVCM was significantly deeper in the BI-TE-CXL group (248.3 ± 25.0 μm) than that of the TE-CXL group (136.5 ± 15.6 μm) in the central cornea (p < 0.001). The cross-linked collagen structures in the central cornea were still present after 12 months in the BI-TE-CXL group. No significant difference in sub-basal nerve density between the two groups (p > 0.05). Conclusions: Following BI-TE-CXL, CDVA was significantly improved, accompanied by deeper demarcation line depth and persistent crosslinked structures in the central corneal stroma. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to determine the preferred protocol of corneal collagen cross-linking (CXL) in the treatment of progressive keratoconus. Methods: Relevant studies were retrieved in PubMed, EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL). Maximum keratometry value (Kmax), best spectacle-corrected visual acuity (BSCVA), manifest refraction spherical equivalent (MRSE), and endothelial cell density (ECD) were evaluated in network meta-analysis. Results: Eight randomized controlled trials (RCTs) were included. Low-level evidence suggested that aCXL with 30mW/cm2 for 3 min (aCXL-3) might be the best protocol for reducing BSCVA (65.22%) but worst protocol for reducing MRSE (51.53%). aCXL with 18mW/cm2 for 5 min (aCXL-5) might be the best protocol for reducing Kmax (39.58%) and MRSE (77.85%) but might be the worst for preserving ECD (50.98%). aCXL with 9mW/cm2 for 10 min (aCXL-10) might be the best protocol for preserving ECD (31.53%). Conclusion: Overall, three protocols of aCXL are comparable in therapeutic efficacy and safety for treating progressive keratoconus. Despite no direct data comparing the efficacy of each technique according to different patients' profiles, it is reasonable to state that aCXL-5 may be the best for patients at early-stage to reduce Kmax and MRSE, aCXL-3 may be the best for patients at mid-stage to improve BSCVA, and aCXL-10 may be the best for patients at late-stage to preserve DEC. [ABSTRACT FROM AUTHOR]

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.

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. [ABSTRACT FROM AUTHOR]

This article reports a novel surgical technique of partial-thickness compression sutures without descemetopexy with air or gas for the management of acute hydrops in keratoconus. Two patients presented with localized corneal edema with a Descemet membrane (DM) tear in the left eye. Tomography of the right eye revealed localized steepening with increased maximum keratometry and decreased central pachymetry. They were diagnosed with keratoconus in the right eye and acute corneal hydrops (ACH) in the left eye. Compression sutures were passed through the stroma without touching the DM. The anterior chamber was not entered at all at any point during the surgery. Resolution of edema was noted intraoperatively itself. Further resolution of edema was noted from the first postoperative day which markedly reduced within the first week. A corneal scar with no edema was seen at six weeks. In both the patients, vision at presentation was counting fingers close to face which improved to 20/60 and 20/50, respectively, at the last visit. [ABSTRACT FROM AUTHOR]

Purpose. To develop a method of accelerated ultraviolet crosslinking with an initial corneal thickness equal to or less than 400 microns using a protective donor corneal flap. Definition of safety and effectiveness of this method in the treatment of progressive keratoconus.Material and methods. 20 patients (20 eyes) with a diagnosis of progressive keratoconus 2–3 stages were included in the study. The accelerated crosslinking was carried out with an IROC-VX-2000 device (Switzerland). A protective donor corneal flap was cut out by using a Femto LDV Z8 femtosecond laser («Ziemer», Switzerland). The thickness of the protective flap of the donor cornea was determined as the difference between 450 μm and the obtained value of the patient’s pachymetry in 30 minutes of saturation with Dextralink in μm.Results. Indicators of uncorrected visual acuity and corrected visual acuity returned to the level of preoperative values and did not tend to decrease until the end of the observation period for 6 months. The average keratometry indices gradually decreased: after 3 months – 50.3±1.5 μm, after 6 months – 48.9±1.8 μm, by 12 months – 46.7±2.1 μm. A decrease in elevation indicators of the anterior and posterior surfaces was marked on elevation maps throughout the observation period.Conclusion. The proposed ultraviolet crosslinking technique using a protective donor corneal flap in patients with corneal thickness 400 μm or less is reproducible. This technique proves its effectiveness and safety and allows to stabilize the condition in patients with progressive keratoconus with adequate visual function. This makes this technique necessary, taking into account the lack of adequate cross-linking technology with a thin cornea.

Abstract Introduction The purpose of this non-comparative, prospective, observational study was to evaluate the post-US Food and Drug Administration approval outcomes of epithelium-off, full-fluence, Dresden protocol corneal collagen crosslinking (CXL) for the treatment of progressive keratoconus (KCN) and post-refractive corneal ectasia at a US academic tertiary medical center. Methods This study involved 125 eyes of 97 patients with KCN and 13 eyes of 12 patients with post-refractive ectasia which underwent CXL between November 2016 and September 2019. Best spectacle-corrected visual acuity (BSCVA) and corneal topographic parameters were measured preoperatively, at postoperative month 1 (POM-1), and between postoperative months 3 and 24 (POM 3–24). Results Best spectacle-corrected visual acuity, flat keratometry, steep keratometry, and mean corneal power worsened at POM-1 (p

To compare the efficacy of epithelium-off corneal collagen crosslinking (CXL) with transepithelial CXL in patients with progressive keratoconus with a follow-up of 3 years, taking into account the patients' age and the location of the corneal ectasia. In this prospective study participated 64 eyes with progressive keratoconus were included in this long-term study, of which 31 eyes were treated by epithelium-off CXL and 33 by transepithelial CXL. All of the patients with a follow-up of 36 months were evaluated for visual variables (corrected distance visual acuity (CDVA), corneal aberrations, and corneal densitometry), structure variables (astigmatism, keratometry, corneal asphericity, maximum posterior elevation, corneal thickness, and corneal volume), and keratoconus index variables. After corneal CXL, CDVA improved significantly in both central and paracentral keratoconus, with greater improvement in the centrals (p = 0.001), asphericity at 6 mm improved in central keratoconus (p = 0.047). In the epi-off group, there was a significant improvement in coma-like (p = 0.038), higher-order aberrations (p = 0.036), asphericity at 8 mm (p = 0.049), asphericity at 10 mm (p = 0.049), and index of surface variance (p = 0.049). Although both techniques halted and stabilized the progression of keratoconus, epithelium-off CXL was more effective. In addition, after the corneal CXL, there was a greater degree of regularization of the corneal surface and, therefore, a greater improvement in the CDVA with central keratoconus than with paracentral keratoconus. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study is to compare the long-term effects of transepithelial corneal crosslinking with two continuous cycles of iontophoresis (EI-CXL) and conventional corneal crosslinking (C-CXL) in adults with progressive keratoconus. Methods: A retrospective analysis was conducted in adults who underwent C-CXL or EI-CXL between 2013 and 2015. Visual acuity, corneal tomography, anterior segment optical coherence tomography, in vivo corneal confocal microscopy (IVCM), and endothelial cell count (ECC) were performed preoperatively and 5 years postoperatively. Results: Sixty-eight patients with a mean age of (24.3 ± 3.8) years were included, 34 for each group. After CXL, UCVA or BCVA remained stable, while the spherical diopter, cylinder diopter, spherical equivalent, and Kmax significantly decreased at 1, 2, and 3 years in both groups than baseline (P < 0.05). No significant differences were found in any refractive or tomographic parameters as well as the minimal corneal thickness between groups during follow-up. At 5 years, Kmax was slightly higher in EI-CXL group (58.16 ± 6.28) than that of C-CXL group (57.46 ± 4.98). At 3 and 5 years, the minimal corneal thickness in C-CXL group was still significantly lower than baseline (P < 0.05). IVCM demonstrated the demarcation zone at a mean depth of (302.0 ± 41.7) μm after C-CXL, and at (251.2 ± 28.1) μm after EI-CXL (P < 0.001). Keratocyte repopulation was detectable at all follow-up timepoint in both groups. Postoperative complications including progression were recorded in 6 patients (11.7%) after C-CXL and 3 patients (8.8%) after EI-CXL. ECC remained stable in both groups. Conclusion: EI-CXL showed approximate efficacy with C-CXL in stabilizing progressive keratoconus in adults. EI-CXL has the potential to be a preferable transepithelial protocol. [ABSTRACT FROM AUTHOR]

Introduction: The purpose of this non-comparative, prospective, observational study was to evaluate the post-US Food and Drug Administration approval outcomes of epithelium-off, full-fluence, Dresden protocol corneal collagen crosslinking (CXL) for the treatment of progressive keratoconus (KCN) and post-refractive corneal ectasia at a US academic tertiary medical center. Methods: This study involved 125 eyes of 97 patients with KCN and 13 eyes of 12 patients with post-refractive ectasia which underwent CXL between November 2016 and September 2019. Best spectacle-corrected visual acuity (BSCVA) and corneal topographic parameters were measured preoperatively, at postoperative month 1 (POM-1), and between postoperative months 3 and 24 (POM 3–24). Results: Best spectacle-corrected visual acuity, flat keratometry, steep keratometry, and mean corneal power worsened at POM-1 (p < 0.01) with a return to preoperative values at POM 3–24. Maximum keratometry (Kmax) steepened at POM-1 and then improved beyond preoperative levels at POM 3–24 (p < 0.01 and p = 0.03, respectively). Pachymetry at the apex and pupil decreased at POM-1 and POM 3–24 (p = 0.03). Pachymetry at the thinnest point decreased at POM-1 and trended toward reduction at POM 3–24 (p < 0.001 and p = 0.06, respectively). Visual and tomographic outcomes were similar between pediatric and adult populations, and between KCN and post-refractive ectasia patients. Conclusions: Real-world results of CXL in the USA are similar to those reported in prior studies, demonstrating an initial worsening of BSCVA, pachymetry, and keratometry followed by corneal flattening and preservation of visual acuity. Improvements in Kmax and stability in visual acuity were observed over 24 months in children and adults with progressive KCN or post-refractive ectasia. [ABSTRACT FROM AUTHOR]

Purpose: To use novel indices to determine the prevalence of KC and its progression in patients aged 10–30 years with Down syndrome. Study design: Cohort population-based study. Methods: Two hundred twenty-six of 250 invited Down syndrome patients were enrolled. The diagnostic criteria were confirmed by two independent expert examiners using slit-lamp examinations and topographic indices measured by Pentacam HR (Oculus Optikgeräte): maximum keratometry centered on the steepest point (zonal Kmax-3 mm), Ambrósio's relational thickness (ART), inferior-superior asymmetry (IS-value), Belin/Ambrósio deviation value (BAD-D), the Tomographic and Biomechanical Index (TBI), and a posterior elevation map. In the KC cases, Corvis ST (Oculus Optikgeräte) was done. All the KC cases completed the second phase in 2017. Results: KC was identified in 28 patients (12.39%; 95% confidence interval: 8.2–17.9%): 20 bilateral and eight unilateral cases. Of these, 24 were in the ≤ 20-years age group, and four, in the > 20-years age group. The frequency of KC was not significantly correlated with age (P = 0.804) or gender (P = 0.322). In the KC cases, the mean zonal Kmax-3 mm, ART-max, IS-value, BAD-D, CBI, and TBI were 50.40 ± 5.88 D, 321.63 ± 111.94 μm, 1.99 ± 2.51, 3.73 ± 3.12, 0.54 ± 0.61, and 0.86 ± 0.20, respectively, and the minimum corneal thickness was 492.17 ± 42.67 μm. Of the 28 patients, 39.6% showed progression, and all were in the ≤ 20-years age group. Conclusion: The prevalence of KC in Down syndrome patients is significantly higher than that reported in non-Down syndrome individuals of the same age groups. The progression rate is approximately similar to that of the non-Down syndrome population. Screening programs should be applied to prohibit serious visual impairment in these populations. [ABSTRACT FROM AUTHOR]

AIM: To compare the effectiveness and safety between modified cross-linking (MC) and standard cross-linking (SC) in mild or moderate progressive keratoconus. METHODS: Eligible studies were retrieved from four electronic databases, including CENTRAL, Clinical Trials gov, PupMed and OVID MEDLINE. We set post-surgical maximum K value (Kmax) as the primary outcome. In addition, uncorrected and corrected distant visual acuity (UDVA and UDVA), spherical equivalent (SE), endothelial cell density (ECD), central cornea thickness (CCT) and depth of demarcation line (DDL) were Meta-analyzed as secondary outcomes. Mean differences for these outcomes were pooled through either a random-effect model or fixed-effect model according to data heterogeneity. RESULTS: Twenty-four comparative studies either on accelerated cross-linking (AC) compared with SC or on trans-epithelial cross-linking (TC) compared with SC were included and pooled for analysis. The results indicated that MC was significantly inferior to SC at delaying Kmax deterioration [AC vs SC 0.49 (95% CI: 0.04-0.94, I2=75%, P=0.03); TC vs SC 1.15 (95% CI: 0.54-1.75, I2=50%, P=0.0002)]. SE decreased significantly for SC when compared to AC [0.62 (95% CI: 0.38-0.86, I2=22%, P

Ahmed Abdel-Karim El-Massry, Amgad Mostafa Dowidar, Tamer Hamdy Massoud, Baher Guirguis Daoud Tadros Department of Ophthalmology, Faculty of Medicine, Alexandria University, Alexandria Governorate, Egypt Background: Corneal collagen cross-linking (CXL) is the only treatment currently available to arrest the progression of keratoconus. The procedure consists of photopolymerization of stromal collagen fibers induced by combined action of a photosensitizing substance (riboflavin or vitamin B2) and ultraviolet-A light.Purpose: To determine changes in the ocular higher-order aberrations (HOAs) after CXL and its correlation with changes in visual acuity.Design: Prospective interventional study.Subjects and methods: This study was conducted on 30 eyes of 16 patients with progressive keratoconus documented between 2012 and 2014. Patients were treated with epithelium-off CXL and followed for a minimum of 6 months. The following ocular HOAs were measured and analyzed using I-Tracey Aberrometer: coma, trefoil, spherical aberration, astigmatism, and total HOAs.Results: There was statistically significant improvement in uncorrected visual acuity and best-corrected visual acuity between the preoperative and 6-month evaluations (P

Collagen corneal cross-linking (CXL) is an invasive pharmacological treatment strategy used for corneal ectatic disorders and is currently the only treatment capable of halting the progression of the disease. In the past 20 years, the conservative management of progressive corneal ectasia has changed, thanks to this procedure that produces strengthening of the corneal tissue through the photochemical reaction generated by the combined action of riboflavin and ultraviolet A radiation. Many modified protocols have been implemented to halt the progression of the disease and to delay or prevent visual loss and surgical procedures such as corneal transplantation. Because of the variety of different protocols that are currently used, the results that are being reported are very variable, and could generate some confusion in relation to the true efficacy of the procedure. The aim of this review was to provide an overview of the aforementioned protocols that are designed to maintain the efficacy of CXL in halting the progression of the disease but avoiding the major limitations of the procedure. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Riboflavin- and ultraviolet (UV)-A-mediated collagen cross-linking of the cornea is a frequently used therapeutic measure for the treatment of progressive keratoconus (PK). First, riboflavin increases cross-linking and second, it serves as a protective shield to other deep ocular structures. However, pharmacogenomic variation in riboflavin efficacy is reported. As the Northeast Indian population represents a genetically diverse group of population compared to mainstream India, we have assessed the efficacy of the procedure in a northeastern population with PK. METHODS: In this study, 78 eyes with PK were included (n = 39 in the treatment arm and n = 39 in the control arm). The primary objective was to evaluate the effect of corneal collagen cross-linking using riboflavin (C3R) (epithelium off) on maximum keratometry. The secondary objectives were evaluation of change in corneal topography parameters, i.e., minimum keratometry (Kmin), simulated keratometry (Sim K), subjective refraction (cylinder power, spherical power, and spherical equivalent [SE]), uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), and contrast sensitivity (CS) and safety (intraocular pressure, endothelial cell density, and percentage hexagonality) at 1, 3, and 6 months following C3R procedure. RESULTS: Statistically significant improvement was noted in Kmin(6 months), Sim K (3 and 6 months), cylinder power (3 and 6 months), spherical power (3 and 6 months), SE (3 and 6 months), BCVA (6 months), and UCVA (1, 6 months) in the C3R group (n = 39) when compared to the control group (n = 39). The mean CS decreased at 1 month and gradually improved to achieve statistically significant value at 6 months in the C3R group (P < 0.05). CONCLUSION: Riboflavin-assisted C3R treatment showed promising efficacy in the treatment of PK patients in our population. As the collagen turnover rate of cornea is 2–3 years and the progression of PK is highly variable, we need long-term studies to evaluate the efficacy of C3R over time, requirement of repeat therapy, and safety of repeat cross-linking. [ABSTRACT FROM AUTHOR]

Corneal collagen cross-linking is advance technique use ultraviolet A with riboflavin (vitamin B2) to increase corneal stiffness. The aim of this study to evaluate visual outcome, keratometric reading and corneal topographic outcomes after corneal collagen cross-linking in a progressive keratoconus. A prospective study was conducted from March 2016 to March 2017, 44 eyes with progressive keratoconus were treated by photosensitizer and ultraviolet-A. Preoperative examination included uncorrected and best corrected visual acuity, slit lamp examination of the cornea and corneal topography. A soft bandaging contact lens was putting after complete the procedure. On the fifth day, we removing the contact lens and postoperative follow up was done every month for six months. Forty four eyes included in this study, 56.8% were male and 43.2% were female, age group was 15-30 years. After six months follow-up there were 17eyes exhibited improvement of uncorrected visual acuity by one line while 15 cases exhibited improvement by two or more line. Three eyes (6.8%) lost two or more lines of UCVA. In the majority of the cases (63.6%) keratometric reading was stable. This study revealed improvement in the visual results of the corneal collagen cross-linking and confirmed the safety and effectiveness of this procedure. [ABSTRACT FROM AUTHOR]

PURPOSE: The purpose of this study is to compare the safety and efficacy of transepithelial corneal crosslinking (CXL) with epithelium-off crosslinking (epithelium-off CXL) in the treatment of progressive keratoconus in adult Pakistani population. MATERIALS AND METHODS: Sixty-four eyes of 64 consecutive patients of progressive keratoconus were included in this quasi-experimental study. Thirty-two eyes received transepithelial CXL with Peschke TE (0.25% riboflavin (Vitamin B2), 1.2% hydroxypropyl methylcellulose (HPMC), 0.01% benzalkonium chloride) and 32 eyes received epithelium-off CXL with Peschke M (0.1% riboflavin (Vitamin B2) 0.1%, HPMC 1.1%.) The cornea was then exposed to ultraviolet A light at an irradiance of 3 mW/cm2 for 30 min. The primary outcome measure, clinical stabilization of keratoconus was defined as an increase of no more than 1D in Kmaxat 1 year. Other parameters evaluated at baseline and 3, 6, 12, and 18 months postoperatively were uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent (SE), astigmatism (Ast), simulated keratometry, steep keratmetry (steep K), and corneal thickness at thinnest point (pachy thin). RESULTS: Both epithelium-off CXL and transepithelial CXL groups showed a significant reduction in Kmax, steep K, simulated K, corneal pachymetry at all test points (P < 0.05) with significantly greater reductions achieved in epithelium-off CXL group at 18 months follow-up. The mean UDVA, CDVA, SE, Ast significantly improved in both groups (P < 0.05). The mean postoperative UDVA and CDVA between the groups were not significant at 12 months (P = 0.650, 0.018, respectively). Clinical stabilization was achieved in 94% of eyes in epithelium-off CXL and 75% of eyes in transepithelial CXL. In epithelium-off CXL, three eyes exhibited stromal haze resolved by corticosteroid treatment. No complication was documented in transepithelial CXL group. CONCLUSION: Transepithelial CXL is not recommended to be replaced completely by standard epithelium-off CXL due to continued ectatic progression in 25% of cases. However, thin corneas, unfit for standard epithelium-off CXL, can benefit from transepithelial CXL.

Purpose. To evaluate the efficacy of intrastromal keratoplasy with intra-corneal ring segment (ICRS) implantation in combination with corneal collagen cross-linking in the treatment of early and advanced keratoconus. Material and methods. In the study 183 eyes with keratoconus were included: 87 eyes (47.5%) with the stage II and 96 eyes (32.5%) with stage III. The ICRS were implanted as a first step of treatment in 98 cases (53.5%), cross-linking was performed 3 months later. In 85 cases (46.4%) the CXL was performed as a first step followed by the ICRS implantation after 3 months. Results. Patients were examined 3, 6, 24 months after surgery. Best functional results were obtained after the ICRS implantation: UCVA and BCVA increased by 3-5 lines, mean keratometry readings decreased by 3.5-4D, the average spherical equivalent decreased by 3.2-2.75D, astigmatism decreased by 2.6-3.9D. After the subsequent CXL procedure, there was a slight improvement of the obtained results. The results obtained in the groups І and II differed insignificantly and were almost identical. At 24 months after surgery some deterioration of functional results was detected in 23.1-26.7% of cases. In the rest of the cases, the obtained effect remained stable.Conclusions. 1. Intra-corneal ring segments implantation and cross-linking are aimed to halt a keratoconus progression and have been successfully used to treat the disease of initial and far-advanced stages. 2. The combination of both methods gives better functional results regardless of which method is performed as a first step. 3. The choice of method to be performed as a first step of treatment depends on the central pachymetry and corneal thickness in a 5-7mm zone of ectasia. 4. Interval between the first and the second step of treatment has to be 3 months or more.

Purpose: To compare results between standard and accelerated corneal collagen cross‐linking (CXL) for the treatment of progressive keratoconus. Methods: We performed literature searches in PubMed, Cochrane Library, Web of Science, ISRCTN registry, ClinicalTrials.gov, and EMBASE for studies comparing conventional Dresden (C‐CXL) and accelerated CXL (A‐CXL). Outcomes were clinical results and changes in corneal properties. Weighted mean differences were used to evaluate the effects. Results: Here, 22 studies with 1158 eyes (C‐CXL: 577 eyes; A‐CXL: 581 eyes) were included. At the last follow‐up, C‐CXL was superior regarding minimum keratometry (p < 0.00001) and demarcation line depth (p < 0.00001), whereas A‐CXL should be favoured when considering minimum corneal thickness (p = 0.0005). No differences in uncorrected and corrected distance visual acuity (p = 0.09 and 0.98), spherical equivalent (p = 0.11), spherical and cylindrical error (p = 0.29 and 0.32), maximal and average keratometry (p = 0.05 and 0.65), central corneal thickness (p = 0.15), corneal biomechanical properties (p ≥ 0.21 respectively), time of reepithelialization (p = 0.76), subbasal nerve density (p = 0.69), endothelial cell density (p = 0.30) and morphology (p ≥ 0.40 respectively) were found among both groups. Conclusion: Consideration of less corneal thinning favours A‐CXL, whereas the deeper demarcation line and greater changes in minimum keratometric values in C‐CXL may indicate a higher treatment efficacy. Altogether, C‐CXL, as well as A‐CXL, provides successful results in the strengthening of corneal tissue. [ABSTRACT FROM AUTHOR]

PURPOSE: The purpose of this study is to compare the safety and efficacy of transepithelial corneal crosslinking (CXL) with epithelium-off crosslinking (epithelium-off CXL) in the treatment of progressive keratoconus in adult Pakistani population. MATERIALS AND METHODS: Sixty-four eyes of 64 consecutive patients of progressive keratoconus were included in this quasi-experimental study. Thirty-two eyes received transepithelial CXL with Peschke TE (0.25% riboflavin (Vitamin B2), 1.2% hydroxypropyl methylcellulose (HPMC), 0.01% benzalkonium chloride) and 32 eyes received epithelium-off CXL with Peschke M (0.1% riboflavin (Vitamin B2) 0.1%, HPMC 1.1%.) The cornea was then exposed to ultraviolet A light at an irradiance of 3 mW/cm2 for 30 min. The primary outcome measure, clinical stabilization of keratoconus was defined as an increase of no more than 1D in Kmax at 1 year. Other parameters evaluated at baseline and 3, 6, 12, and 18 months postoperatively were uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent (SE), astigmatism (Ast), simulated keratometry, steep keratmetry (steep K), and corneal thickness at thinnest point (pachy thin). RESULTS: Both epithelium-off CXL and transepithelial CXL groups showed a significant reduction in Kmax, steep K, simulated K, corneal pachymetry at all test points (P < 0.05) with significantly greater reductions achieved in epithelium-off CXL group at 18 months follow-up. The mean UDVA, CDVA, SE, Ast significantly improved in both groups (P < 0.05). The mean postoperative UDVA and CDVA between the groups were not significant at 12 months (P = 0.650, 0.018, respectively). Clinical stabilization was achieved in 94% of eyes in epithelium-off CXL and 75% of eyes in transepithelial CXL. In epithelium-off CXL, three eyes exhibited stromal haze resolved by corticosteroid treatment. No complication was documented in transepithelial CXL group. CONCLUSION: Transepithelial CXL is not recommended to be replaced completely by standard epithelium-off CXL due to continued ectatic progression in 25% of cases. However, thin corneas, unfit for standard epithelium-off CXL, can benefit from transepithelial CXL. [ABSTRACT FROM AUTHOR]

Objective: The purpose of this study was to evaluate the safety and efficacy of transepithelial corneal collagen cross linking (TE-CXL) with modified riboflavin and accelerated UVA irradiance in thin corneas with pachymetry less than 400 microns at thinnest point, untreatable by epithelium off corneal collagen cross linking(CXL) in adult Pakistani population with progressive keratoconus. Methods: This quasi experimental study included twenty six eyes of 26 patients with progressive keratoconus who underwent accelerated transepithelial CXL in Armed forced institute of ophthalmology with 12 months follow up. Modified riboflavin, ParaCel ((riboflavin 0.25%, Benzalkonium chloride, EDTA, Trometamol, hydroxypropyl methylcellulose) and vibeX Xtra (riboflavin 0.25%) (Avedro, USA)) were applied to cornea in two stages. Uncorrected and Corrected Distant Visual Acuities (UDVA, CDVA), spherical equivalent (SE), astigmatism, pachymetry at thinnest point (Pachy thin), apex keratometry (Kmax), simulated and steep keratometry (Sim K, steep K) were measured at baseline and at 3, 6 and 12 months post operatively. The cornea was then exposed to accelerated UVA irradiance of 9mW/cm2 for 10 min (total dose 30 mW/cm2). Results: The mean age of the patient was 24.54±5.16 years. UDVA, CDVA, SE, astigmatism significantly improved at all postoperative test points (p=0.000, 0.004, 0.000, 0.004 respectively). Kmax and pachy thin were significantly reduced over baseline at 1 year (p=0.000, 0.004 respectively). Topographic indices Sim K and steep K did not show significant changes. No intra or post-operative complications were reported. Conclusion: Transepithelial accelerated CXL with modified riboflavin is a safe and effective procedure which halt disease progression in thin corneas with progressive keratoconus. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the efficacy of transepithelial corneal collagen crosslinking (TE-CXL) in patients with progressive keratoconus. Patients and methods: This is a prospective interventional consecutive study carried out on 30 eyes of 18 patients with progressive keratoconus who underwent TE-CLX using both ParaCel™ (riboflavin 0.25%, hydroxy propyl methyl cellulose, NaCl, ethylenediaminetetraacetic acid [EDTA], Tris, and benzalkonium chloride) and vibeX-Xtra (riboflavin 0.22%, phosphatebuffered saline solution). The procedure was carried out at Ebsar Eye Center in Egypt in the period from 2012 to 2014. The follow-up visits were scheduled on days 1, 3, 6, and 12 months after treatment. Results: There were statistically significant improvements (P<0.001) in the mean best-corrected visual acuity (0.54±0.22 preoperatively vs 0.61±0.19 at 12 months postoperatively), the mean manifest refraction spherical equivalent (MRSE; -6.16±3.90 diopters [D] preoperatively and -5.91±3.72 D at 12 months postoperatively), and the mean preoperative corneal astigmatism (-3.39±2.11 D preoperatively and -2.46±2.60 D at 12 months postoperatively. Conclusion: TE-CXL could halt the progression of keratoconus in adult patients. TE-CXL resulted in a statistically significant improvement in best-corrected visual acuity, manifest refraction, refractive and corneal astigmatism and K values in keratoconus patients at the 12-month follow-up. Larger sample sizes and longer follow-ups are required in order to make meaningful conclusions. [ABSTRACT FROM AUTHOR]

ABSTRACT Purpose. To evaluate the efficacy of intrastromal keratoplasy with intra-corneal ring segment (ICRS) implantation in combination with corneal collagen cross-linking in the treatment of early and advanced keratoconus. Material and methods. In the study 183 eyes with keratoconus were included: 87 eyes (47.5%) with the stage II and 96 eyes (32.5%) with stage III. The ICRS were implanted as a first step of treatment in 98 cases (53.5%), cross-linking was performed 3 months later. In 85 cases (46.4%) the CXL was performed as a first step followed by the ICRS implantation after 3 months. Results. Patients were examined 3, 6, 24 months after surgery. Best functional results were obtained after the ICRS implantation: UCVA and BCVA increased by 3-5 lines, mean keratometry readings decreased by 3.5-4D, the average spherical equivalent decreased by 3.2-2.75D, astigmatism decreased by 2.6-3.9D. After the subsequent CXL procedure, there was a slight improvement of the obtained results. The results obtained in the groups І and II differed insignificantly and were almost identical. At 24 months after surgery some deterioration of functional results was detected in 23.1-26.7% of cases. In the rest of the cases, the obtained effect remained stable. Conclusions. 1. Intra-corneal ring segments implantation and cross-linking are aimed to halt a keratoconus progression and have been successfully used to treat the disease of initial and far-advanced stages. 2. The combination of both methods gives better functional results regardless of which method is performed as a first step. 3. The choice of method to be performed as a first step of treatment depends on the central pachymetry and corneal thickness in a 5-7mm zone of ectasia. 4. Interval between the first and the second step of treatment has to be 3 months or more.

Background: Corneal collagen cross-linking with riboflavin, also known as collagen cross-linking (CXL), involves the application of riboflavin solution to the eye that is activated by illumination with ultraviolet A (UVA) light. We survey here the topographic corneal changes one year after CXL in patients with corneal keratoconus. Materials and Methods: This prospective randomized clinical trial study comprised 66 patients with progression of keratoconus during one year who were enrolled at Feiz University Referral Eye Center in Isfahan. Before and after the operation, patients were examined with slit lamp and funduscopic examinations and measurement of uncorrected visual acuity (UCVA), and best spectacle-corrected visual acuity (BSCVA) was done with a logarithm of minimal angle of resolution (logMAR) scale. Corneal topographic and pachymetry values were derived from Orbscan II. The paired t-test test was used for statistical analyses with SPSS software version 20 (SPSS Inc., Chicago, IL, USA). Results: All 66 patients completed postoperative follow-up at 12 months. The mean age of the patients was 22.4 ± 5.4 years (range: 18-29 years). Thirty-six (54.55%) subjects were men and 30 (45.45%) were women. The mean preoperative sphere was −2.66 ± 2.14 diopter (D), the mean cylinder was −3.97 ± 2.29, and the mean spherical equivalent (SE) was −4.64 ± 2.56. Postoperatively, the mean sphere was −2.22 ± 2.57 D, the mean cylinder was −3.60 ± 2.40 D, and SE was −4.02 ± 2.93 D (P = 0.037). SE also demonstrated a mean difference of 0.62 ± 0.37 D significantly (P = 0.006).The mean diameter of preoperative posterior best-fit sphere (BFS) was 6.33 ± 0.35mm (range: 5.51-7.73 mm) before operation, and it improved to 6.28 ± 0.34mm (range: 4.36-6.13 mm) after operation; the difference was significant (P = 0.039). Conclusion: Our study showed a significant improvement in topographic corneal changes and refractive results in patients with corneal ectasia after CXL.

Aim: To assess the results of corneal collagen cross-linking with riboflavin using ultraviolet - A light for keratoconus at one year in Indian eyes. Materials and Methods: Sixty-eight eyes of 41 patients with progressive keratoconus were included in this retrospective study. All eyes completed was 12 months of follow-up and 37 eyes had a one-year follow-up. The maximum follow-up was 16 months. Ocular examinations including refraction, best corrected visual acuity (BCVA), corneal topography, were recorded at each visit. Results: The mean age was 16.9 ± 3.5 years (range 12-39 years) and the mean follow-up was 10.05 ± 3.55 months (range six to 16 months). Thirty seven eyes with a follow-up of at least 12 months were analyzed. The preoperative values on the day of treatment were compared with postoperative values of the 12-month examination. This showed that BCVA improved at least one line in 54% (20/37) of eyes and remained stable in 28% (10/37) of eyes ( P =0.006). Astigmatism decreased by a mean of 1.20 diopter (D) in 47% (17/37) of eyes ( P =0.005) and remained stable (within ± 0.50 D) in 42% (15/37) of eyes. The K value of the apex decreased by a mean of 2.73 D in 66% (24/37) of eyes ( P =0.004) and remained stable (within ± 0.50 D) in 22% (8/37) of eyes. The maximum K value decreased by a mean of 2.47 D in 54% (20/37) of eyes ( P =0.004) and remained stable (within ± 0.50 D) in 38% (14/37) of eyes. Corneal Wavefront analysis revealed that spherical and higher-order aberrations did not show significant variations in the follow-up period. The coma component showed a very significant reduction at six months after treatment and persisted throughout the follow-up period ( P =0.003) Conclusion: The results show a stabilization and improvement in keratoconus after collagen cross-linking in Indian eyes. This suggests that it is an effective treatment for progressive keratoconus.

Background/Purpose Keratoconus is the most common primary corneal ectatic disease and has considerable importance in public health. Corneal collagen crosslinking (CXL) is a procedure to mitigate progression of keratoconus and reduce demand for corneal transplantation. The aim of this study was to evaluate the effect of CXL on corneal topographic and uncorrected distance visual acuity (UDVA) by Oculus Pentacam in the 15–30-year-old population. Methods In this descriptive–analytic study, we enrolled 38 eyes of 27 patients suffering from progressive keratoconus who were candidates for CXL. UDVA and the anterior and posterior corneal curvatures assessed prior to and 12 months after CXL. Data were analyzed by the paired t test and p < 0.05 was considered significant. Results One year after the CXL, mean UDVA significantly improved 0.1 ± 0.25 logarithm of the minimal angle of resolution ( p = 0.012). Changes for steep keratometry values, flat keratometry, and mean keratometry on the anterior corneal surface were statistically significant (all p < 0.005). However, the difference observed in maximum keratometry and astigmatism was not significant ( p = 0.421 and p = 0.745, respectively). After 12 months, all four keratometry values on the posterior corneal surface had increased significantly ( p < 0.005), while no significant change observed in astigmatism ( p = 0.303). Conclusion Corneal collagen crosslinking has been revealed as an effective and minimally invasive intervention for the treatment of progressive keratoconus that can improve UDVA. [ABSTRACT FROM AUTHOR]

Aim and Design: A retrospective, nonrandomized, single-center clinical study was designed to evaluate the outcomes of corneal collagen crosslinking (CXL) for progressive keratoconus in Iranian patients 12 months after CXL. Settings: This study was carried out at Navid Didegan Eye Center, a private clinic, Mashhad, Iran. Materials and Methods: Ninety-two eyes of 53 subjects with progressive keratoconus were evaluated in this study. All eyes completed 1-year follow-up. The outcome measures were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), sphere and cylinder refraction, keratometry, and corneal thickness. Comparison of baseline and 1-year postoperative data is reported in this study. The Wilcoxon signed-ranked and Student's t-tests were used for statistical analyses. P < 0.05 was statistically significant. Results: The mean age was 21.5 ± 3.4 years (range, 16 -30 years). Thirty-one (58.5%) of the subjects were men and 22 (41.5%) were women. Mean baseline UCVA and BSCVA were 0.61 ± 0.31 and 0.06 ± 0.12 logarithm of minimal angle of resolution (logMAR), respectively. One year postoperatively UCVA was 0.31 ± 0.25 logMAR and BSCVA was 0.0 ± 0.01 logMAR. UCVA and BSCVA were statistically higher postoperatively (P < 0.001, both parameters). The mean astigmatism decreased by 0.78 ± 1.49 diopter (D) with significant variation during the follow-up period (P < 0.001). Mean baseline simulated keratometry (SIM K) was 46.94 ± 2.37 D and decreased to 46.0 ± 2.33 D on year postoperatively (P < 0.001). Conclusion: Corneal CXL seems to be efficient in stabilization of progressive keratoconus progression in Iranian patients at 1 year of followup. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate efficacy and safety of contact lens-assisted corneal cross-linking (CACXL) among progressive keratoconus patients with thin corneas., Setting: Private eye hospital., Design: Cross-sectional study., Methods: Thirty-six eyes of 36 consecutive patients with progressive keratoconus and thinnest corneal thickness of 380-400 µm after epithelium removal were included. CACXL was performed based on use of a dextran-free isotonic (>0.1%) riboflavin solution with hydroxypropyl methylcellulose (HPMC, 1.1%) after epithelial removal and placement of a riboflavin-soaked contact lens without an ultraviolet filter on the cornea and ultraviolet irradiance. Data on best distance corrected (CDVA) and uncorrected (UDVA) visual acuity, manifest sphere (D), manifest cylinder (D), K1 (D), K2 (D), mean keratometry (D) and Kmax (D) values, endothelial cell count and mean depth of demarcation line were recorded preoperatively and at the postoperative 1-year., Results: Post-operative 1-year data revealed significant increases in UDVA (0.23  ±  0.15 vs. 0.17  ±  0.13 D, p < 0.001) and CDVA (0.44  ±  0.18 vs. 0.36  ±  0.17 D, p < 0.001) values and a significant reduction in the mean Kmax (from 56  ±  3.3D to 55  ±  3.2 D, p < 0.001), K2 (from 49.7  ±  3.2 D to 49.52  ±  3.11 D, p  =  0.049), manifest sphere (from -1.93  ±  2.21 D to -1.55  ±  2.02 D, p  =  0.001) and manifest cylinder (from -2.83  ±  1.67 D to -2.39  ±  1.36 D, p < 0.001) values along with a similar endothelial cell count. The mean depth of demarcation line was mean 230 (SD17.05, range 200 to 262) at postoperative 1-month., Conclusions: Our findings indicate favourable 1-year postoperative outcome of CACXL in progressive keratoconus patients with thin cornea in terms of improved visual acuity and keratectasia status as well as endothelial safety.

We aimed to compare the effect of accelerated and conventional corneal collagen cross-linking (CXL) on visual, refractive, and topographic parameters in patients with progressive keratoconus. Between December 2014 and February 2016, at Imam Khomeini Hospital, Ahvaz Jundishapur University of Medical Sciences, Iran, we compared 37 eyes of 21 patients treated by conventional CXL (CCXL; 3 mW/cm2 in 30 minutes) with 34 eyes of 18 patients treated by accelerated CXL (ACXL; 18 mW/cm2 in 5 minutes) based on generalizing estimation equation analysis in terms of corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), corneal endothelial cell indices, and topographic parameters before and at 3, 6 and 12 months after the operation. The mean UDVA and spherical equivalent changes were similar in the two groups, but an improvement in CDVA was only observed in the CCXL group (P = 0.003). Keratometry (minimum and maximum) was significantly decreased in the CCXL group (P = 0.043 and P = 0.008, respectively). Indices of keratoconus progression-surface asymmetry index (SAI), keratoconus prediction index (KPI), and keratoconus index (KCI)-were significantly lower in the CCXL group than in the ACXL group (P = 0.002, P < 0.001, and P < 0.001, respectively). The thinnest corneal thickness (TCT) was not significantly different between the two groups (P = 0.15). The reduction of corneal endothelial cell density was also similar between the two groups; however, polymorphism and polymegethism were significantly lower in the ACXL group than in the CCXL group. In conclusion, we showed that although ACXL at 18 mW/cm2 slowed keratoconus progression safely during a 1-year follow-up, CCXL at 3 mW/cm2 may be superior in the prevention of keratoconus progression., Competing Interests: No funding or sponsorship was received for this study. All named authors meet the International Committee of Medical Journal Editors (ICMJE) criteria for authorship for this manuscript, take responsibility for the integrity of the work as a whole, and have given final approval for the version to be published.

Background: Keratoconus is a bilateral non-inflammatory corneal disease. Collagen cross-linking (CXL) is a new treatment option for the disease that uses ultraviolet A light irradiation and riboflavin administration. The aim of this study is to evaluate the effect of CXL on corneal topographic and refractive values in patients with keratoconus younger than 18 years of age., Materials and Methods: For the clinical trial study, 37 patients (64 eyes) younger than 18 years of age with progressive keratoconus were included. Age, sex, family history of keratoconus, and history of allergic disorders and eye rubbing were recorded. Refractive, topographic, and topometric indices were evaluated before and 12 months after the CXL with 3mW for 30 minutes., Results: Mean age (±SD) of the patients was 15.83 ± 1.53 years; 26 (70.3%) of the 37 patients were male. Fourteen (37.8%) had positive family history of keratoconus, 11 (29.7%) had history of allergic disorders, and 15 (40.5%) had positive history of eye rubbing. Of the refractive values, cylinder value decreased significantly from -4.50 ± 0.29 to -4.11 ± 0.28 (P = 0.001). Also, the logarithm of minimal angle of resolution (logMAR) uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) improved significantly 12 months after CXL (P = 0.012 and 0.001, respectively). Maximum keratometry before and after the operation was 53.82 ± 0.72 and 53.33 ± 0.72, respectively (P = 0.018). Differences for simulated K values, the thinnest cornea pachymetry, keratoconus index (KI), index of highest asymmetry (IHA), and index of highest decentration (IHD) before and 12 months after the CXL were statistically significant (P = 0.015, 0.034, <0.001, 0.017, 0.019, and 0.004, respectively)., Conclusion: CXL improves the refractory, topographic, and topometric indices in patients with keratoconus younger than 18 years of age.

Background: Corneal collagen cross-linking (CXL) is gaining popularity as a treatment in arresting the progression of keratoconus. It is a relatively new therapy using ultraviolet-A (UVA) with a photosensitizer to increase corneal stiffness. The purpose of this study was to evaluate visual, keratometric and topographic outcomes after corneal CXL in progressive keratoconic eyes., Materials and Methods: In this prospective nonrandomized clinical study, 140 eyes of 110 patients with progressive keratoconus were treated by combined riboflavin/UVA CXL. Mean sphere, mean cylinder uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), manifest refractive spherical equivalent, corneal topography, pachymetry, and endothelial cell morphology were examined preoperatively and 12-24 months postoperatively., Results: The preoperative mean sphere was -3.33 ± 3.13 diopter (D) and decreased to -3.09 ± 3.09 D (P = 0.007). The preoperative mean cylinder was -4.05 ± 2.29 D and changed to -3.79 ± 2.23 D (P = 0.011). UDVA changed from 0.95 ± 0.64 logarithm of the minimum angle of resolution (logMAR) to 0.85 ± 0.59 logMAR (P = 0.003). Thirty-five eyes (25%) gained one or more lines of preoperative UDVA, 87 eyes (62.1%) did not change and 18 eyes (12.8%) lost one or more lines of the preoperative UDVA. CDVA in 80% of the patients remained stable (no lines lost). Statistical analysis of keratometry, pachymetry, and endothelial cell count did not show the significant difference after surgery., Conclusion: Our study showed improvement in visual and refractive results of the corneal CXL and confirmed that CXL is the safe and effective procedure.

Background: Corneal collagen cross-linking with riboflavin, also known as collagen cross-linking (CXL), involves the application of riboflavin solution to the eye that is activated by illumination with ultraviolet A (UVA) light. We survey here the topographic corneal changes one year after CXL in patients with corneal keratoconus., Materials and Methods: This prospective randomized clinical trial study comprised 66 patients with progression of keratoconus during one year who were enrolled at Feiz University Referral Eye Center in Isfahan. Before and after the operation, patients were examined with slit lamp and funduscopic examinations and measurement of uncorrected visual acuity (UCVA), and best spectacle-corrected visual acuity (BSCVA) was done with a logarithm of minimal angle of resolution (logMAR) scale. Corneal topographic and pachymetry values were derived from Orbscan II. The paired t-test test was used for statistical analyses with SPSS software version 20 (SPSS Inc., Chicago, IL, USA)., Results: All 66 patients completed postoperative follow-up at 12 months. The mean age of the patients was 22.4 ± 5.4 years (range: 18-29 years). Thirty-six (54.55%) subjects were men and 30 (45.45%) were women. The mean preoperative sphere was -2.66 ± 2.14 diopter (D), the mean cylinder was -3.97 ± 2.29, and the mean spherical equivalent (SE) was -4.64 ± 2.56. Postoperatively, the mean sphere was -2.22 ± 2.57 D, the mean cylinder was -3.60 ± 2.40 D, and SE was -4.02 ± 2.93 D (P = 0.037). SE also demonstrated a mean difference of 0.62 ± 0.37 D significantly (P = 0.006). The mean diameter of preoperative posterior best-fit sphere (BFS) was 6.33 ± 0.35mm (range: 5.51-7.73 mm) before operation, and it improved to 6.28 ± 0.34mm (range: 4.36-6.13 mm) after operation; the difference was significant (P = 0.039)., Conclusion: Our study showed a significant improvement in topographic corneal changes and refractive results in patients with corneal ectasia after CXL.