Permanent corneal haze after riboflavin-UVA-induced cross-linking in keratoconus

Retrospective evaluation of haze development after riboflavin-ultraviolet (UV) A-induced corneal collagen cross-linking (CXL).

One hundred sixty-three eyes of 127 patients with stage 1-3 keratoconus according to Krumeich's classification were included in this retrospective analysis. Follow-up was 1 year. Preoperatively and at all follow-up examinations uncorrected visual acuity, best spectacle-corrected visual acuity (BSCVA), slit-lamp microscopic findings, corneal topography, and corneal thickness were recorded.

At 1 year after CXL, 149 (91.4%) eyes of 114 patients had a clear cornea without stromal haze (control group), whereas 14 eyes (8.6%) of 13 patients developed clinically significant stromal haze (haze group). Preoperatively, the mean keratometry (K) value of the apex was 62.1+/-13.8 diopters (D) in the control group and 71.1+/-13.2 D in the haze group (P=.02). The mean corneal thickness before the procedure was 478.1+/-52.4 mum in the control group and 420.0+/-33.9 mum in the haze group (P=.001). Uncorrected visual acuity and BSCVA, which were similar between groups preoperatively (P=.59 and P=.75, respectively), were improved in the control group (P=.023 and P=.001, respectively), but reduced in the haze group (P=.012 and P=.004, respectively) postoperatively.

The parameters defining the stage of keratoconus, such as K-value and corneal thickness, could be considered predicting factors for possible development of corneal haze after riboflavin-UVA-induced CXL. Advanced keratoconus should be considered at higher risk of haze development after CXL due to low corneal thickness and high corneal curvature.