Oxygen in Corneal Collagen Crosslinking to Treat Keratoconus: A Systematic Review and Meta-Analysis.

Abstract

PURPOSE:

Keratoconus is a disorder that results in visual loss from increased corneal high-order aberrations and irregular astigmatism and reduces quality of life. The primary treatment for progressive keratoconus is crosslinking (CXL). Recently, it has been suggested that oxygen enhances the type II photodynamic reaction of CXL that is oxygen dependent. Our study investigated the effect of increased oxygen availability in epithelium-on CXL on visual acuity and corneal curvature.

METHODS:

We searched PubMed, EMBASE, Medline, Web of Science, and Scopus databases on November 3, 2021. We included studies that reported increased oxygen availability during CXL in patients with keratoconus published within the last 10 years. A meta-analysis on the primary outcomes, maximum keratometry, and corrected distance visual acuity, was conducted.

RESULTS:

The search yielded 108 publications which were screened and assessed for eligibility. Six studies were included in the systematic review and 5 studies were included in our meta-analysis of the outcomes of increased oxygen availability in accelerated CXL. The meta-analysis on data after 6 months of follow-up found a significant decrease in mean maximum keratometry of 1.2 diopter (95% confidence interval: 0.2-2.3; P =0.02) and an improvement in mean corrected distance visual acuity by 0.08 logMAR (95% confidence interval, 0.02-0.13; P =0.01). There were no serious adverse events reported.

CONCLUSIONS:

Increasing oxygen during epithelium-on CXL improved visual acuity and produced corneal flattening without any serious adverse events in patients with keratoconus. The demarcation line depth was significantly higher with oxygen compared to the control group. Further data are required with a control group and long-term follow-up across a range of CXL protocols for implementation into standard clinical practice.

• Authors: Grace A Borchert, Stephanie L Watson, Himal Kandel
• Journal: Asia-Pacific journal of ophthalmology (Philadelphia, Pa.) (Asia Pac J Ophthalmol (Phila)) Vol. 11 Issue 5 Pg. 453-459 (Sep 01 2022) ISSN: 2162-0989 [Electronic] China
• PMID: 36094374 (Publication Type: Journal Article, Meta-Analysis, Systematic Review)
• Copyright: Copyright © 2022 Asia-Pacific Academy of Ophthalmology. Published by Wolters Kluwer Health, Inc. on behalf of the Asia-Pacific Academy of Ophthalmology.

Chemical References

• Cross-Linking Reagents
• Photosensitizing Agents
• Collagen
• Oxygen
• Riboflavin

Topics

• Collagen (therapeutic use)
• Corneal Stroma
• Corneal Topography
• Cross-Linking Reagents (therapeutic use)
• Humans
• Keratoconus (drug therapy)
• Oxygen (therapeutic use)
• Photosensitizing Agents (therapeutic use)
• Quality of Life
• Riboflavin (therapeutic use)
• Ultraviolet Rays