Corneal Cross-linking for Keratoconus and Post-LASIK Ectasia and Failure Rate: A 3 Years Follow-up Study

Abstract PURPOSE: To report the response of keratoconus(KC) and post-LASIK ectasia (referred as ‘’ectasia’’) to the corneal crosslinking(CXL) and to compare the rate of progression between KC and ectasia at 3 years.METHODS: Retrospective cohort study of patients undergoing CXL for either KC or ectasia. 54 eyes(31 patients) with ectasia and 111 eyes(67 patients) with KC were included in the study. Corrected distance Visual acuities(CDVA), refraction, keratometry(K) and pachymetry were followed over 3 years. Simultaneous Photorefractive keratectomy(PRK) and CXL was performed on 20 KC and 20 ectasia eyes. Intrastromal Corneal Ring Segments(ICRS) was performed on 51 KC and 6 ectasia eyes.RESULTS: In KC, CDVA, spherical equivalence, sphere, cylinder and mean K improved at 3 years post-CXL(p-value<0.05), but, these values improved without reaching a statistical significance in ectasia. 12 of 54 eyes with ectasia(22.2%) and 4 of 111 eyes(3.6%) with KC had progression post CXL(p-value:0.0001). Ectasia patients diagnosed with progression were older at presentation (36.1 years) than non-progressive ectasia patients(31 years)(p-value:0.02), and also older than KC patients.Sub-analysis excluding PRK and ICRS cases showed that there was an improvement in mean sphere (from -5.23±4.2D to-4.46±3.89D)(p-value:0.03) cylinder(from 2.54±1.68D to 1.97±1.51D)(p-value:0.03) mean keratometry(from 46.81±3.78D to 46.01±3.25D)(p-value:0.006) in KC patients 3 years post CXL(40patients). Compared to baseline, all the mean refractive and tomographic variables deteriorated at 3 years post CXL in ectasia(28 patients)(p-value>0.05). Also, 2 of 40 patients with KC(5%) vs. 7 of 28 patients with ectasia(25%) had progression 3 years post-CXL and the difference between both groups remained statistically significant(p-value:0.027). CONCLUSION: Eyes with post-LASIK ectasia seems to be less responsive to CXL than KC.