[Corneal scar development after cross-linking in keratoconus]

Abstract

Background: Corneal scar development after riboflavin-UVA-induced corneal collagen cross-linking (CXL) was retrospectively evaluated.

Patients and methods: A total of 163 CXL-treated eyes in 127 patients with stage 1-3 keratoconus according to Krumeich's classification were included in this retrospective analysis. The follow-up period was 1 year. At the first and at all follow-up examinations uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), biomicroscopic findings, corneal topography and corneal thickness were recorded.

Results: At 1 year following CXL, 149 eyes (91.4%) of 114 patients had a clear cornea without corneal scar (control group), while 14 eyes (8.6%) of 13 patients developed clinically significant corneal scar (scar group). Preoperatively, the mean K value of the apex was 62.1 ± 13.8 D in the control group and 71.1 ± 13.2 D in the scar group (P=.02). The mean value of corneal thickness before the procedure was 478.1 ± 52.4 μm in the control group and 420.0 ± 33.9 μm in the scar group (P=.001). The UCVA and BCVA, which were preoperatively similar between groups (P=.59, P=.75 respectively), were postoperatively improved in the control group (P=.023, P=.001 respectively), but reduced in the scar group (P=.012, P=.004 respectively).

Conclusion: K-values and corneal thickness could be considered as predictive factors for the possible development of corneal scarring after riboflavin-UVA-induced CXL. Advanced keratoconus appears to be associated with a higher risk of corneal scar development due to lower corneal thickness, greater curvature and intrinsic tissue characteristics.