Corneal Cross-linking with Hypo-osmolar Riboflavin Solution in Thin Keratoconic Corneas

Purpose: To evaluate the 1-year results of keratoconic eyes with thin corneas that were treated by a hypo-osmolar riboflavin solution and ultraviolet A collagen cross-linking (CXL).

Design: Retrospective, nonrandomized study.

Methods: setting: Department of Ophthalmology, Carl Gustav Carus University Hospital, Dresden, Germany. study population: Thirty-two eyes of 29 patients with progressive keratoconus and a corneal thickness of less than 400 μm (without the epithelium). intervention: Application of a hypo-osmolar riboflavin solution to the cornea after its de-epithelization followed by ultraviolet A collagen cross-linking. main outcome measures: Thirty-two eyes with a follow-up within 1 year were evaluated before and after the procedure. Examinations comprised an evaluation of visual acuity, corneal topography, slit-lamp microscopy, and corneal thickness measurements.

Results: Before surgery, the mean corneal thickness (with the epithelium) was 382.3 ± 41.9 μm, and after the removal of epithelium, the thickness of the cornea was reduced to 337.0 ± 51.9 μm. After the application of the hypo-osmolar riboflavin solution, this value increased to 451.8 ± 46.7 μm. Before surgery, the mean K-value of the apex of the keratoconus was 65.6 ± 11.2 diopters, and 1 year after treatment, this value remained unchanged at 64.9 ± 11.0 diopters (P = .839). Mean best-corrected visual acuity at the time of the treatment was 0.63 ± 0.37 logarithm of the minimal angle of resolution, and 1 year after the treatment, this value was not statistically different (0.59 ± 0.42 logarithm of the minimal angle of resolution; P = .662). At the last follow-up examination, which was 1 year after the procedure, all corneas were transparent, without any scarring lesions in the stroma.

Conclusions: The results of our study, using hypo-osmolar riboflavin solution in a cross-linking procedure of thin corneas, show a stability of keratoconus one year after cross-linking. Application of the hypo-osmolar riboflavin solution preserved cross-linked corneas from developing stromal scars.