Systematic review and meta-analysis: epithelium-off vs transepithelial and standard vs accelerated corneal collagen cross-linking for keratoconus

Session Details

Session Title: Presented Poster Session: Corneal Cross-Linking

Venue: Poster Village: Pod 3

First Author: : C.McAlinden UK

Co Author(s): :    D. Qi Li   B. Ruixue Tu   Q. Wang   D. O'Brart   Y. Huang   J. Huang        

Abstract Details

Purpose:

To systematically compare: 1. Standard epithelium-off corneal collagen cross-linking (SCXL) and transepithelial corneal collagen cross-linking (TECXL) for treating keratoconus. 2. Epithelial-off standard (SCXL) to accelerated corneal collagen cross-linking (ACXL) for the treatment of keratoconus.

Setting:

Wenzhou Medical University, China. Key Laboratory of Vision Science, Ministry of Health of the People's Republic of China, Wenzhou. University Hospitals Bristol NHS Foundation Trust, United Kingdom Hywel Dda University Health Board, Carmarthen, United Kingdom St. Thomas' Hospital, United Kingdom King's College, London, United Kingdom

Methods:

For objective 1: Primary outcomes were changes at 1 year in uncorrected distance visual acuity, maximum keratometry (Kmax), and mean keratometry (mean K). Secondary outcomes were changes at 1 year in corrected distance visual acuity, mean refractive spherical equivalent, central corneal thickness, endothelial cell density, and the occurrence of adverse events. For objective 2: Primary outcomes were changes in uncorrected distance visual acuity, maximum keratometry (Kmax), and mean keratometry (mean K). Secondary outcomes were changes in corrected distance visual acuity, mean refractive spherical equivalent, central corneal thickness (CCT), and endothelial cell density (ECD).

Results:

1. SCXL showed a greater reduction in mean K [SMD 0.28; 95%CI 0.03-0.53; P=0.03] compared with TECXL. SCXL had a comparable effect on reducing mean K with TECXL protocols using chemical enhancers (SMD 0.05; 95%CI -0.36 to 0.45; P=0.82) but a greater reduction in mean K compared with TECXL with current iontophoretic protocols (SMD 0.43; 95% CI 0.10-0.75; P=0.01). 2. SCXL showed a greater reduction in Kmax (SMD 0.32; 95%CI 0.16, 0.48) than ACXL. The decrease in CCT (SMD 0.32; 95% CI 0.03, 0.61) and ECD (SMD 0.26; 95%CI 0.06, 0.46) was less with ACXL than with SCXL.

Conclusions:

With the exception of less reduction in mean K with current iontophoretic protocols, analysis of the limited number of comparative studies available seems to demonstrate that SCXL and TECXL have a comparable effect on visual, refractive, pachymetric, and endothelial parameters at 1 year after surgery. Further follow-up is required to determine whether these techniques are comparable in the long-term. SCXL has a greater effect in terms of reduction in Kmax than ACXL, while ACXL induces less reduction in CCT and ECD than SCXL. Further well-designed randomized controlled trials comparing ACXL and SCXL are indicated.

Financial Disclosure:

None