PURPOSE To report the outcomes of keratoconic eyes after corneal collagen cross-linking (CXL) with a hypo-osmolar riboflavin and ultraviolet-A (UVA) irradiation in patients with thin corneas (minimum corneal thickness less than 400 um after epithelial removal).
DESIGN Prospective case series.
METHODS Eight patients (12 eyes, with minimum corneal thickness less than 400 um after epithelial removal) were included in the study. All patients underwent CXL using a hypo-osmolar riboflavin solution to the cornea after its de-epithelization. Uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) (decimal scale), manifest refraction (diopters, D), central corneal thickness (CCT), endothelial cell density, and topography were evaluated before and at months 1 and 3 after the procedure.
RESULTS Before surgery, the mean corneal thickness (with the epithelium) was 404.0±26.36um, and after the removal of epithelium, the thickness of the cornea was reduced to 365.8±31.36um. After the application of the hypo-osmolar riboflavin solution, this value increased to 442.5±36.72 um and decreased to 412.6±26.45um at 1 month and remained at 3 month (410.4 ±32.91um). Before surgery, the mean K-value of the apex of the keratoconus was 65.9±12.8 diopters, and this value remained unchanged at 66.5±11.7 diopters at 1 month after treatment, and decreased to 64.9±17.3 diopters at 3 month. No significant decrease of endothelial cell density was observed (preoperative: 2702±210 cells/mm2, 3 month after treatment: 2651±180 cells/mm2). Mean best-corrected visual acuity at the time of the treatment was 0.56±0.47 logarithm of the minimal angle of resolution, and 3 month after the treatment, this value was not different (0.62±0.52 logarithm of the minimal angle of resolution).
CONCLUSIONS The results of our study showed a stability and safety of keratoconus in thin corneas after cross-linking by using hypo-osmolar riboflavin solution.