Abstract
Purpose: :
To evaluate the clinical safety and efficacy of PRK in the visual rehabilitation of eyes previously treated with riboflavin/UVA induced collagen crosslinking for stabilizing the progression of post–LASIK ectasia and keratoconus.
Methods: :
Prospective, non–randomized clinical pilot study. Seven eyes of 5 patients with moderate to advanced ectasia following LASIK were included. After pre–treatment with UVA collagen cross–linking, and at the 3 month interval 6 eyes were further treated with topography–guided PRK, utilizing the Wavelight, Allegretto TCAT platform in order to facilitate visual rehabilitation.
Results: :
In all treated eyes, the progression of keratoconus appeared to stabilize. In 6 eyes regression with a reduction of maximal keratometry readings by 3.01 D and of the refractive error by 2.14 D was found. Corneal and lens transparency, ECC and IOP 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 20/30) and BSCVA (20/50 to 20/22) improved drastically in all 6 eyes treated further with PRK.
Conclusions: :
Collagen crosslinking may offer promise in the stabilization of progression of iatrogenic keratoconus following LASIK by increasing cornea rigidity. This stability may enable excimer refractive surgery correction, which has been traditionally contra–indicated. Long term results are necessary to evaluate the duration of the stiffening effect and exclude long term side effects.
Keywords: refractive surgery: LASIK • refractive surgery: PRK • keratoconus