Corneal collagen crosslinking in progressive keratoconus: Changes in corneal irregularity indices and correlation with the best spectacle-corrected visual acuity

PURPOSE: To report the mean refractive and topographic changes in progressive keratoconus (KC) patients post corneal collagen crosslinking (CXL) to assess the progression of corneal irregularity indices and their relationship with best spectacle-corrected visual acuity (BSCVA). SETTING: Ocular Microsurgery Institute (IMO) of Barcelona, Spain. METHODS: This is a retrospective uncontrolled study in eyes with progressive KC. In all 62 eyes from 48 patients, BSCVA, mean K, corneal irregularity at 3 mm and 5 mm were measured before CXL, at six months, and then annually until the last visit. For data analysis, patients were divided into three groups according to their mean preoperative K: group 1 included 12 patients with mean K value less than 43.9 D, group 2 included 41 patients with mean K value between 44-47.9 D, and group 3 included 10 patients with mean K value greater than 48 D. RESULTS: All patients showed an improvement in BSCVA from 0.13 to 0.06 (p < 0.001) and a statistically significant decrease in maximum keratometry (Kmax) from 48.22 to 47.25 D (p < 0.001) and minimum keratometry (Kmin) from 45.7 to 44.89 D (p < 0.001). Measurement of corneal irregularity also showed a statistically significant decrease at 3 mm from 4.71 to 4.25 (p < 0.001) and at 5 mm from 4.87 to 4.51 (p < 0.007). No statistically significant results were found according to study group. CONCLUSION: The improvement in ocular surface regularity indices was statistically significant in all patients studied, with a possible association between changes in corneal irregularity, corneal flattening and other topographic changes and the improvement in vision observed in KC patients undergoing CXL.