Accelerated Corneal Collagen Cross-Linking in Thin Keratoconic Corneas

Abstract

To report the outcomes of accelerated corneal collagen cross-linking in patients with thin corneas (minimum corneal thickness < 400 µm). Thirty-four eyes of 34 patients with a minimum corneal thickness less than 400 µm were included. All patients underwent accelerated corneal collagen cross-linking (irradiance power of 30 mW/cm² at 3 minutes with a total surface dose of 5.4 J/cm²). Uncorrected (UDVA) and corrected distance visual acuity (CDVA), manifest refraction (diopters [D]), and topography were evaluated at baseline and at the 1-, 6-, and 12-month follow-up visit. Endothelial cell density (cells/mm²) was calculated preoperatively and postoperatively at 12 months. The corneal stromal demarcation line was measured using anterior segment optical coherence tomography at 1 month postoperatively. The mean age of all patients (14 women and 20 men) was 23.08 ± 3.90 years (range: 16 to 29 years). UDVA and CDVA increased but not significantly. UDVA improved from 0.67 ± 0.32 (20/93 ± 20/41 Snellen) to 0.56 ± 0.28 logMAR (20/72 ± 20/38 Snellen) (P = .033) and CDVA improved from 0.49 ± 0.19 (20/61 ± 20/30 Snellen) to 0.42 ± 0.19 logMAR (20/52 ± 20/30 Snellen) (P = .009) at the last follow-up visit. The mean spherical and cylindrical refractions did not significantly change (P = .100 and 0.139, respectively). At the last follow-up visit, the flat keratometry decreased from 47.40 ± 2.52 to 46.95 ± 2.48 D, steep keratometry decreased from 51.04 ± 3.71 to 50.62 ± 3.57 D, and apex keratometry decreased from 57.58 ± 4.49 to 56.26 ± 4.47 D (P = .001, = .0019, = .001, respectively) from baseline. The mean endothelial cell density changed from 2,726.02 ± 230.21 to 2,714.58 ± 218.26 cells/mm² at 12 months postoperatively (P =.086). The results of this study revealed that accelerated corneal collagen cross-linking stabilized the progression of keratoconus without a significant endothelial cell density loss during the 12 months of follow-up.