Accelerated versus Conventional Corneal Collagen Cross-Linking for Progressive Keratoconus

Abstract We aimed to compare the effect of accelerated and conventional corneal collagen cross-linking (CXL) on visual, refractive, and topographic parameters in patients with progressive keratoconus. Between December ۲۰۱۴ and February ۲۰۱۶, at Imam Khomeini Hospital, Ahvaz Jundishapur University of Medical Sciences, Iran, we compared ۳۷ eyes of ۲۱ patients treated by conventional CXL (CCXL; ۳ mW/cm۲ in ۳۰ minutes) with ۳۴ eyes of ۱۸ patients treated by accelerated CXL (ACXL; ۱۸ mW/cm۲ in ۵ minutes) based on generalizing estimation equation analysis in terms of corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), corneal endothelial cell indices, and topographic parameters before and at ۳, ۶ and ۱۲ months after the operation. The mean UDVA and spherical equivalent changes were similar in the two groups, but an improvement in CDVA was only observed in the CCXL group (P = ۰.۰۰۳). Keratometry (minimum and maximum) was significantly decreased in the CCXL group (P = ۰.۰۴۳ and P = ۰.۰۰۸, respectively). Indices of keratoconus progression—surface asymmetry index (SAI), keratoconus prediction index (KPI), and keratoconus index (KCI)—were significantly lower in the CCXL group than in the ACXL group (P = ۰.۰۰۲, P < ۰.۰۰۱, and P < ۰.۰۰۱, respectively). The thinnest corneal thickness (TCT) was not significantly different between the two groups (P = ۰.۱۵). The reduction of corneal endothelial cell density was also similar between the two groups; however, polymorphism and polymegethism were significantly lower in the ACXL group than in the CCXL group. In conclusion, we showed that although ACXL at ۱۸ mW/cm۲ slowed keratoconus progression safely during a ۱-year follow-up, CCXL at ۳ mW/cm۲ may be superior in the prevention of keratoconus progression.