COMPARATIVE STUDY BETWEEN PRK AND LASIK XTRA FOR MANAGEMENT OF THIN CORNEAS WITH MODERATE MYOPIA

To compare the results of using PRK alone   versus using lasik and crosslinking (lasik XTRA) for thin corneas between 450- 500um with moderate myopia (6 degree or less)

The Memorial Institute For Ophthalmic Research

Prospective interventional comparative study of (100) eyes ( 50 eye in each group) (30 males and 25 female) aged between 18-50 years with unilateral or bilateral thin cornea and moderate myopia. Patients were done by 1 surgeon in the memorial institute for ophthamic research (MIOR) with follow up period was at least 1years.Inclusion Criteria : patients with unilateral or bilateral thin cornea (450-500 um) , moderate myopia (-6.00 or less ) , all other  parameters in the pentacam are normal .Excluison Criteria : corneal thickness more than 500um or less than 450 um , high myopia more than 6 degree, presence of other suspect parameters in pentacam  , kc  .Surgical Technique :  In PRK use the original technique remove epithelium , apply laser then use Mitomycin for 45 sec .  In lasik xtra create flap , apply laser then use riboflavin for 1.5  min and apply ultraviolet for 1.5 min

     .PreOperative :full ophthalmic examination UCVA , BCVA , cycloplegic refraction , fundus examination , pentacam   .post operative:  follow up healing of epithelium in PRK  , stability of flap in lasik xtra, demarcation line in lasik xtra , stability of post operative refraction , signs of post lasik ectasia .

99 % of eyes  showed improvement in vision with stable refraction over the follow up period  . over follow up for at least 1 year,  only one  eye showed signs of post lasik ectasia  in the lasik xtra group , (3) patients showed delay in the epithelial healing more than 10 days , only 1 patient in lasik xtra group showed regression and need redo after 3 months , 5 patients showed post operative haze (2 in lasik xtra group and 3 in PRK group ) .

using both PRK  or  lasik XTRA for thin corneas with moderate myopia are safe with comparable results in safety and in refractive efficacy  and stability.

No significant complications had occurred in both techniques all over the study