Collagen Crosslinking by Combined Riboflavin/Ultraviolet–A (UVA) Treatment can stop the progression of Keratoconus

Abstract

Abstract: : Purpose: In the course of keratoconus a penetrating keratoplasty is required in approximately 20% of the patients. In previous experimental studies with rabbit and porcine corneas we detected a significant increase in corneal biomechanical stiffness after Riboflavin/Ultraviolet–A induced collagen crosslinking. The aim of this prospective non–randomized clinical pilot study was to evaluate the effect of the new collagen crosslinking method on progression of keratectasia in patient with keratoconus. Methods: Sixty eyes of 48 patients with progressive keratoconus with moderate or advanced keratectasia (maximal k–reading, 41.70 to 72.47 D) were included. After removal of the corneal epithelium photosensitizing Riboflavin drops (0.1% Riboflavin–5–phosphat, 20% Dextran) were applied every 5 minutes and the cornea was exposed to UVA (370nm, 3mW/cm²) in a 1–cm distance for 30 minutes. Data to verify a preoperative progression of keratoconus were available up to 42 months before treatment. Postoperative follow–up ranged from 1 to 38 months. Examinations included visual acuity testing, corneal topography, pachymetry and measurement of endothelial cell density. Results: The k–readings showed a statistically significant progression from the first documented to the preoperative measurements (paired student t test; p = 0.003; 95% confidence interval, –2.375 to –0.511). None of the patients with a follow–up longer than 3 months showed progression of the k–readings in the treated eye (paired Student t test, p = 0.15; 95% confidence interval –0.138 to 0.896). In 31 eyes (51.7%) a postoperative regression of the maximal k–readings with an average reduction of 2.87 ± 2.56 D (range 0.18 to 9.97 D) was observed. Before regression or stabilization of the keratoconus 24 eyes (40%) showed a transient mild to moderate increase of the maximal k–readings. Best corrected visual acuity improved postoperative slightly by 1.4 ± 2.04 lines. Conclusions: Collagen crosslinking by Riboflavin/Ultraviolet–A seems to be a useful and sufficient treatment in patients with advanced keratoconus to prevent further progression. This treatment might be helpful to reduce the need for penetrating keratoplasty in these patients. In a 38 month follow–up no negative side effects of the treatment were seen in our patients.

Keywords: keratoconus • cornea: clinical science • cornea: stroma and keratocytes