Different accelerated corneal collagen cross-linking treatment modalities in progressive keratoconus

Background: To compare the outcomes of two different protocols of accelerated corneal crosslinking (CXL) on visual, corneal high order aberrations (HOA) and topographic parameters in patients with progressive keratoconus. Methods: In this prospective comparative study, sixty-six eyes of 66 patients with progressive keratoconus were divided into two groups; 37 eyes in Group 1 received 18 mWcm(2) for five minutes, and 29 eyes in Group 2 were treated with 9 mW/cm(2) for 10 min. The uncorrected distant visual acuity (UCVA), best-corrected distant visual acuity (BCVA), corneal HOAs and topography parameters were measured preoperatively and postoperatively at the end of 12 months. The data for the two groups were compared statistically. Results: The mean UCVA and BCVA were significantly improved at the postoperative 12 months compared with the preoperative values in both groups (P <0.05 for all). A significant improvement in corneal HOAs was observed in both groups (P <0.05 for all). The change in corneal coma value was significantly higher in Group 2 (P <0.05). The change in keratometric values K1, K2, AvgK and maximum keratometry (AKf) were significantly higher in Group 2 (P <0.05 for all). The regression model showed that the most important factor predicting the change in AKf was the type of CXL (beta =- 0.482, P= 0.005). Conclusions: Accelerated CXL using 10 min of UVA irradiance at 9 mWcm(2) showed better topographic improvements and coma values than five minutes of UVA irradiance at 18 mW/cm(2) independent of keratoconus severity.