Comparison of Sequential vs Same-Day Simultaneous Collagen Cross-Linking and Topography-Guided PRK for Treatment of Keratoconus

Abstract

Purpose: The safety and efficacy of corneal collagen cross-linking (CXL) and topography-guided photorefractive keratectomy (PRK) using a different sequence and timing were evaluated in consecutive keratoconus cases. Methods: This study included a total of 325 eyes with keratoconus. Eyes were divided into two groups. The first group (n=127 eyes) underwent CXL with subsequent topography-guided PRK performed 6 months later (sequential group) and the second group (n=198 eyes) underwent CXL and PRK in a combined procedure on the same day (simultaneous group). Statistical differences were examined for pre- to postoperative changes in uncorrected (UCVA, logMAR) and best-spectaclecorrected visual acuity (BSCVA, logMAR), manifest refraction spherical equivalent (MRSE), keratometry (K), topography, central corneal thickness, endothelial cell count, corneal haze, and ectatic progression. Mean follow-up was 36±18 months (range: 24 to 68 months). Results: At last follow-up in the sequential group, the mean UCVA improved from 0.9±0.3 logMAR to 0.49±0.25 logMAR, and mean BSCVA from 0.41±0.25 logMAR to 0.16±0.22 logMAR. Mean reduction in spherical equivalent refraction was 2.50±1.20 diopters (D), mean haze score was 1.2±0.5, and mean reduction in K was 2.75±1.30 D. In the simultaneous group, mean UCVA improved from 0.96±0.2 logMAR to 0.3±0.2 logMAR, and mean BSCVA from 0.39±0.3 logMAR to 0.11±0.16 logMAR. Mean reduction in spherical equivalent refraction was 3.20±1.40 D, mean haze score was 0.5±0.3, and mean reduction in K was 3.50±1.3 D. Endothelial cell count preoperatively and at last follow-up was unchanged ( P <.05) in both groups. Statistically, the simultaneous group did better ( P <.05) in all fields evaluated, with improvement in UCVA and BSCVA, a greater mean reduction in spherical equivalent refraction and keratometry, and less corneal haze. Conclusions: Same-day simultaneous topography-guided PRK and CXL appears to be superior to sequential CXL with later PRK in the visual rehabilitation of progressing keratoconus. [ J Refract Surg . 2009;25:S812–S818.]