Subepithelial accelerated corneal collagen cross-linking in primary keratoconus

Abstract

Objective To investigate the safety and effectiveness of subepithelial accelerated corneal collagen cross-linking (ACXL) in primary keratoconus. Methods Seventeen primary keratoconus eyes of 17 patients were enrolled in this self-controlled study. After making a complete epithelial flap, the underlying stroma was bathed in a 0.1% riboflavin solution for 10 minutes. The cornea was then treated with a KXL system with 30 mW/cm2 UVA for 4 minutes, providing a total energy of 7.2 J/cm2. The flap was then repositioned. Uncorrected visual acuity (UCVA), manifest refraction, best corrected visual acuity (BCVA), haze score, corneal keratometry, keratoconus index (KI), minimum corneal thickness (CT), and endothelial cell density (ECD) were evaluated preoperatively and at 1 month, 3 months, and 1 year postoperatively.The general linear model of repeated measures, Dunnett t-test, and paired t-test were used for analysis. Results On the first postoperative day, 3 patients had level 2 pain scores and the others had level 1. The corneal epithelium of all eyes recovered on postoperative day 5. One year postoperation, UCVA gradually improved (F=3.245, P<0.05), and the spherical equivalent slowly decreased (F=3.466, P<0.05). The flat K-value and steep K-value decreased following an initial increase (FK1=5.572, P<0.05; FK2=8.659, P<0.01). The decrease in KI was significant (F=3.660, P<0.05). CT decreased by 6% (F=20.501, P<0.01). BCVA, ECD, and the percentage of hexagonal cells did not change significantly. Conclusion Subepithelial ACXL is safe and effective in controlling the progression of primary keratoconus. Key words: Keratoconus; Therapy outcome; Epithelial flap; Corneal collagen cross-linking; Accelerated cross-linking