Corneal collagen cross-linkage in keratoconus

Prospective study on a novel treatment for leaking cystic bleb: Efficacy and safety of collagen crosslinking

IMPORTANCE

Management of cystic bleb leak is difficult. It would be essential to look for a method to strengthen the original pathological conjunctiva and reverse bleb leak.

BACKGROUND

To evaluate the long-term efficacy and safety of collagen crosslinking in patients with leaking cystic bleb.

DESIGN

Prospective interventional case series at a university-based hospital.

PARTICIPANTS

Twelve eyes in 12 subjects with late-onset bleb leak from cystic bleb, without indications for prompt surgical interventions were included.

METHODS

The subjects underwent crosslinking with 0.1% riboflavin application to bleb surface, followed by ultraviolet irradiation for 30 minutes. The subjects were followed up at baseline and at 1 week, 1 month, 3 months, 6 months post-treatment and then every 6 months afterwards.

MAIN OUTCOME MEASURES

Interval from treatment to cessation of bleb leak, recurrence rate of bleb leak and side effects of treatment.

RESULTS

The mean follow-up after crosslinking was 29.33 ± 12.45 months. Bleb leak subsided in 11 (92%) of 12 patients after a single session of crosslinking, after 1 to 8 weeks (median 3 weeks). Time to leak cessation was significantly correlated with the number of prior glaucoma interventions (R = .71, P = .014). Bleb wall at 3 months was significantly thicker than at baseline (0.70 ± 0.67 vs 0.81 ± 0.62 mm, P = .008). None of the patients experienced any complications.

CONCLUSIONS AND RELEVANCE

Crosslinking achieves resolution of cystic bleb leak which lasts for at least 12 months, without the need of subsequent surgical interventions. Crosslinking is a simple, non-invasive treatment for bleb leak. It aims to restore the integrity of conjunctiva.

Transepithelial versus Epithelium off Crosslinking for Treating Keratoconus among Jordanians

Background:

The progression of keratoconus is stabilized with the help of corneal collagen cross-linking (CXL) supported through photosynthesized riboflavin.

Objective:

This study aims to compare the effectiveness of the transepithelial procedure and epithelium off procedure of corneal collagen crosslinking among keratoconus patients in Jordan.

Methods:

The study recruited 80 patients suffering from progressive keratoconus, from a tertiary care setting in Jordan. These participants were randomly divided into two groups; group 1 with 40 participants subjected to transepithelial (Corneal collagen cross-linking) CXL; and 40 participants in group 2 received conventional epithelium off CXL.

Results:

Improvement was observed in the mean contact lens, which corrected distance visual acuity (CDVA) from logMAR 0.332 ± 0.09 (group 1), 0.35 ± 0.09 (group 2) to 0.241 ± 0.07 (group 1), 0.21 ± 0.07 (group 2), respectively at the end of follow-up (12 months). The mean pachymetry improved from 429.81 ± 18.96 μm (group 1), 430.08 ± 17.05 μm (group 2) to 436.5 ± 15.49 μm (group 1), 436.44 ± 12.53 μm (group 2), respectively, after twelve months. Additionally, the mean Sim K astigmatism declined from 7.0 ± 2.0 (group 1), 6.73 ± 1.98 (group 2) to 5.97 ± 1.88 (group 1), 5.53 ± 0.08 (group 2) respectively at twelve months post-treatment. Majority of the patients in group 2 experienced more pain as compared to group 1 participants.

Conclusion:

The effectiveness of a cross-linking procedure related to keratometry readings and corneal thickness showed that conventional (epithelium off) CXL method is more effective than transepithelial CXL.

Corneal Collagen Cross-Linking for Keratoconus: Systematic Review

Purpose

To evaluate the efficacy of collagen cross-linking (CXL) one year after treatment for keratoconus compared to no treatment by summarizing randomized controlled trials (RCTs) using a systematic review.

Methods

Trials meeting the selection criteria were quality appraised, and the data were extracted by two independent authors. The outcome parameters included maximum keratometry (K_max), corneal thickness at the thinnest point, best spectacle-corrected visual acuity (BSCVA), uncorrected visual acuity (UCVA), spherical equivalent (SE) refraction, and cylindrical refraction one year after CXL. We compared the changes in the above parameters with the control group.

Results

We identified five RCTs involving 289 eyes that met the eligibility criteria for this systematic review. The changes in BSCVA from baseline to one year exhibited a significant difference between the two groups. There was no statistically significant difference between the two groups for changes in corneal thickness and cylindrical refraction. We did not conduct a meta-analysis in K_max, UCVA, and SE refraction because their I² values were greater than 50%.

Conclusions

According to the systematic review, CXL may be effective in halting the progression of keratoconus for one year under certain conditions, although evidence is limited due to the significant heterogeneity and paucity of RCTs.

Evaluation of possible relationship between COL4A4 gene polymorphisms and risk of keratoconus

PURPOSE

Keratoconus (KC) is a genetically heterogeneous corneal dystrophy with unknown etiology that causes loss of visual acuity. Evidence has shown that corneas from patients with KC contain reduced amounts of total collagen proteins, and collagen type IV has been suggested as a candidate gene in KC pathogenesis. This study aimed to evaluate the possible associations between collagen type IV alpha-4 chain (COL4A4) polymorphisms (rs2229813 G/A, M1327V and rs2228555 A/G, V1516V) and susceptibility to KC.

METHODS

A total of 262 Iranian subjects including 112 patients with KC and 150 healthy individuals as controls were recruited in this case-control study. Diagnosis was based on clinical examination, electronic refractometry, and keratometry. Genotyping for the COL4A4 rs2229813 and rs2228555 variants was executed using allele-specific polymerase chain reaction and Tetra-ARMS polymerase chain reaction, respectively.

RESULTS

A significant difference was found between the 2 groups regarding allelic and genotyping distribution of COL4A4 polymorphism at position rs2229813 G>A. The COL4A4 rs2229813 AA and GA+AA genotypes were risk factors for developing KC (odds ratio [OR] = 2.1, P = 0.036 and OR = 1.7, P = 0.042, for the AA and GA+AA genotypes, respectively). The COL4A4 rs2229813 A allele was also associated with an increased risk for KC (OR = 1.5, 95% confidence intervals: 1.1-2.2, P = 0.018). However, in our study, we found no association between COL4A4 rs2228555 polymorphism and the risk of KC.

CONCLUSIONS

We suggest that the COL4A4 rs2229813 AA and GA+AA genotypes as well as the A allele play roles as risk factors for developing KC in our population.

Corneal collagen cross-linking in keratoconus: a systematic review and meta-analysis

The aim of this study was to determine the effectiveness of corneal collagen cross-linking (CXL) for the treatment of progressive keratoconus (KC). Some of the published literature, including a few small, randomized controlled trials (RCTs), demonstrated good results after CXL, but large RCTs with long-term follow-up to establish a cause-effect relationship are lacking. Using PubMed, EMBASE, and the Cochrane Library database, we searched for relevant studies published between October 2007 and March 2014. A comprehensive literature search was performed using the Cochrane Collaboration methodology to identify the effectiveness of CXL for treating KC. The primary outcome parameters included uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), refraction, corneal topography, and corneal thickness at baseline and at 1, 3, 6, 12, and 18 months after CXL. A total of 1171 participants (1557 eyes) were enrolled in this meta-analysis. CXL may be effective in halting the progress of KC for at least 12 months under certain conditions. However, further research from randomized trials is needed to confirm our findings.

Keratoconus: current perspectives

Keratoconus is characterized by progressive corneal protrusion and thinning, leading to irregular astigmatism and impairment in visual function. The etiology and pathogenesis of the condition are not fully understood. However, significant strides have been made in early clinical detection of the disease, as well as towards providing optimal optical and surgical correction for improving the quality of vision in affected patients. The past two decades, in particular, have seen exciting new developments promising to alter the natural history of keratoconus in a favorable way for the first time. This comprehensive review focuses on analyzing the role of advanced imaging techniques in the diagnosis and treatment of keratoconus and evaluating the evidence supporting or refuting the efficacy of therapeutic advances for keratoconus, such as newer contact lens designs, collagen crosslinking, deep anterior lamellar keratoplasty, intracorneal ring segments, photorefractive keratectomy, and phakic intraocular lenses.