Thinner Corneas Appear to Have More Striking Effects of Corneal Collagen Crosslinking in Patients with Progressive Keratoconus

Purpose. To analyze the outcomes and difference after UVA/riboflavin corneal collagen crosslinking (CXL) in four different corneal thickness groups of patients with progressive keratoconus. Methods. Retrospective study. Eyes with progressive keratoconus after CXL were divided into 4 subgroups as follows: group 1, thinnest corneal thickness (TCT) <= 400 mu m; group 2, 400 mu m < TCT <= 450 mu m; group 3, 450 mu m < TCT <= 500 mu m; group 4, TCT = 500 mu m. Baseline, 6-month, and 12-month visual acuity, corneal topography, TCT, and endothelial cell density were evaluated. Results. The analysis included 123 eyes of 101 patients. At 6 and 12 months after CXL, there was a mean improvement about visual acuity and keratometry values in all patients. There was a reduction in the change of maximum keratometry (K-max) with the increase of TCT. After 1 year of treatment, it was 3.04 +/- 0.75D in group 1, 2.38 +/- 0.51D in group 2, 1.57 +/- 0.35D in group 3, and 0.31 +/- 0.20D in group 4. Conclusion. CXL is successful in halting the progression of keratoconus and there was a negative linear correlation between TCT and K-max. Advanced cases of progressive keratoconus seemed to obtain more benefits from the flatting effects of CXL.