Abstract
Purpose: :
To evaluate the clinical safety and efficacy of riboflavin/UVA induced collagen cross–linking for stabilizing the progression of post–LASIK ectasia and keratoconus.
Methods: :
7 eyes of 5 patients with moderate to advanced ectasia following LASIK were included. A central corneal abrasion was created, then photosensitizing riboflavin drops were applied and the eyes were exposed to UVA (370 nm, 3 mW/cm2) at a 2 cm distance for 30 minutes. Post operative examinations were performed in the 6 month intervals, including visual acuity testing, corneal topography, slit–lamp examination, endothelial cell count density, elasticity testing with a contact ultrasonic device, and clinical photographic documentation. 6 eyes received further treatment with PRK in 3 months in order to facilitate visual rehabilitation.
Results: :
All treated eyes showed improvement of their ectasia. In 6 eyes, there was a reduction of maximal keratometry readings (mean=3.01 D) and a decrease in refractive error (2.14 D). Corneal and lens transparency, endothelial cell count density and intraocular pressure were unchanged. Cornea elasticity measurements changed from an average 15.75 m/sec pre–op to 32.25 post–op.Visual acuity, both UCVA (20/100 to 20/60) and BSCVA (20/50 to 20/25) improved significantlly in all 7 eyes.
Conclusions: :
Collagen cross–linking may offer promise in the stabilization of progressive ectasia following LASIK by increasing corneal rigidity. This stability may enable excimer refractive surgery correction in keratoconus, which has been traditionally contra–indicated. Long term studies are necessary to evaluate the duration of the stiffening effect and monitor long–term stability.
Keywords: cornea: clinical science • refractive surgery: LASIK • refractive surgery: complications