Standard versus Accelerated Collagen Cross-Linking in Treatment of Keratoconus: Visual, Refractive, and Topographic Outcomes

Abstract

Background: collagen cross-linking (CXL) is an effective, safe and rapidly progressive treatment modality for treatment of mild to moderate keratoconus not only in hindering the progression of the disease but also in improving the visual, refractive and topographic results. Objective: the study aims to compare the outcomes of standard and accelerated cross-linking in treatment of keratoconus. Patients and Methods: the present prospective study evaluated 99 eyes of 52 patients with keratoconus. They were classified into two groups; group (1) included 50 eyes (received standard CXL; 3Mw/cm2 , 30 min) (SCXL group) and group (2) 49 eyes (treated by accelerated CXL; 9Mw/cm2 , 10 min) (ACXL group). Spherical equivalent, uncorrected visual acuity, best-corrected visual acuity, and topographical analysis of the cornea were assessed at baseline and within 3 years postoperative. Simulated keratometry was measured in terms of Sim K-1, Sim K-2, K-max, cylindrical value, thickness of the cornea (at the thinnest point) and Q-value were evaluated. Results: postoperative uncorrected distance visual acuity and corrected distance visual acuity didn’t significantly changed in both groups. Postoperative spherical equivalent significantly decreased in standard CXL compared to accelerated CXL. Standard CXL had a greater effect in decreasing Simk-1, Simk-2, k-max and k-mean. K-max decreased from 52.33±5.55 to 50.35±5.14; P=0.07 and in accelerated group from 54.58±4.35 to 52.74±4.41; P=0.04. Also, postoperative corneal pachymetery (at thinnest location) was found to be more stable in standard CLX group. Conclusion: both standard and accelerated CXL are effective in early keratoconus management with better results in standard CXL procedure.