Assessment of Corneal Cross-Linking Effect on Progressive Keratoconus by Using the ABCD Grading System

The aim of this study was to assess changes in corneal parameters 6 months after corneal cross-linking for progressive keratoconus, using the ABCD system.

This retrospective study was conducted at the King Khaled Eye Specialist Hospital (Riyadh, Saudi Arabia) between January 1 and July 30, 2022. This study included 16 eyes of 16 patients with keratoconus who underwent corneal cross-linking at the same hospital and were at least 18 years old. At least one preoperative (T0) and one postoperative examination was performed for each patient. Six months after the procedure (T1), patients underwent corneal tomography. The parameters A, B, C, and D were also evaluated. Other parameters monitored included maximal keratometry (Kmax) (K1 and K2), Belin/Ambrósio Enhanced Ectasia Display, and index vertical asymmetry. The progression of ectasia was identified by a consistent change in at least two parameters: steepening of the anterior corneal surface or the posterior corneal surface, thinning or an increase in the rate at which the corneal thickness changed from the periphery to the thinnest point, where the magnitude of the change was greater than the normal noise of the testing system.

Among the patients, 68.8% were men. The patients' average age was 25.8±5 years. Throughout the 6-month postoperative follow-up, parameters A, B, and C exhibited substantial changes (P = 0.000 for parameters A, B, and C). Parameter A increased 6 months after surgery, whereas parameters B and C decreased. Preoperatively and 6 months after surgery, Kmax, K1, and Belin/Ambrosio-enhanced ectasia demonstrated substantial differences. However, parameter D, K2, and the average pachymetric progression index did not change significantly.

Anterior and posterior corneal curvatures and corneal thickness profiles can be useful for monitoring the progression of keratoconus and the success of the corneal cross-linking operation.