Changes in the ABCD keratoconus grade after corneal cross linking

Abstract

AbstractPurposeTo assess the changes in the ABCD keratoconus staging system after 3 and 6 months and Material corneal cross linking.MethodsThirty one eyes of 31 pationts with keratocnus who were corneal cross linking with the rebofelavin A and ultraviolet ray laser were assessed preoperative and postoperative assessments included determination of distance corrected visual acuity (DCVA), refraction. and Scheimpflug tomography with the Pentacam HR. In the ABCD keratoconus staging system, the elements A, B, C, and D stand for anterior and posterior radii of curvature in a 3.0‐mm zone centered on the thinnest point (TP), corneal thickness at the TP, and DCVA, respectively.ResultsCorneal cross linking produced no significant changes (preoperatively vs. postoperatively) in the anterior (6.91 ± 0.39 vs. 6.92 ± 0.41 vs. 6.94 ± 0.40 mm, p = 0.397) and posterior (5.29 ± 0.42 vs. 5.23 ± 0.44 vs. 5.26 ± 0.44 mm, p = 0.003) radii of curvature of the 3‐mm zone centered on the corneal TP associated with a statistically significant invariant in the DCVA (0.82 ± 0.16 vs. 0.76 ± 0.18 vs. 0.79 ± 0.20 in the decimal notation, p = 0.066) with a little improvement in the corneal thickness at the TP (446.77 ± 89.01 vs. 453.96 ± 38.16 vs. 457.64 ± 37.93 µm, p < 0.001). The most changes occurred in element B of the ABCD keratoconus classification. and elements A, C and D did not show changes in their postoperative stages after corneal cross linking. ABCD keratoconus staging before corneal cross linking was A1B2C1D1 and changed to A1B2C1D1 3and 6 months after surgery.ConclusionThe ABCD staging system provides a more comprehensive guide that better illustrates the structural changes and visual acuity as one aspect of visual function after the corneal cross linking.