[The clinical study of corneal cross-linking with hypo-osmolar riboflavin solution in thin keratoconic corneas]

To evaluate the clinical results of keratoconic eyes with thin corneas that were treated by using corneal collagen cross-linking with hypo-osmolar riboflavin solution.

Retrospective, nonrandomized study. Fifteen eyes of 15 patients with progressive keratoconus and corneal thickness of less than 400 µm (without the epithelium) were included in this study. Application of hypo-osmolar riboflavin solution to the cornea for 30 minutes after its de-epithelialization was followed by ultraviolet A collagen cross-linking. Corneal thickness was measured with anterior segment OCT before surgery, after epithelial removal, and after hypotonic riboflavin solution application. Before the ultraviolet A application was started, we must be sure that the thinnest cornea was equal to or greater than 400 µm. Examinations comprised an evaluation of uncorrected distance visual acuity and best corrected visual acuity, slit-lamp microscopy, corneal topography, and endothelial cell counting after the procedure.

Before surgery, the mean corneal thickness (with the epithelium) was (399.27 ± 17.87) µm, and after the removal of epithelium, the thickness of the cornea was reduced to (354.00 ± 18.57) µm. After the application of the hypo-osmolar riboflavin solution, this value increased to (477.73 ± 20.87) µm. The improvements in visual acuity and keratometry readings occurred during the follow-up. No statistically signiflcant differences were found between preoperative and postoperative endothelial cell counts. No complications such as scarring lesions in the stroma and corneal endothelial damage were observed throughout the study period.

The results of our study, using hypo-osmolar riboflavin solution in a cross-linking procedure in thin corneas, show a stability of keratoconus 12 months after cross-linking.