BIOMECHANICAL INVESTIGATION OF CORNEAL ST ABILITY AFTER PRK

Background: Photorefraktive keratectomy (PRK) is the most frequent ref ractive surgical procedure worldwide. The central corneal thickness is reduced due to removal of the anterior stroma, including Bowman's lay er, with a laser beam. This procedure results in considerable alterati ons of the corneal structure. What does this mean for the mechanical p roperties of the cornea? Methods: lntraocular pressure was increased v ia a 180 degrees tilt. Before and during this procedure, corneal topog raphy was measured by photokeratoscopy. We examined 26 patients after PRK and 25 controls who had not undergone any surgical procedure. Resu lts: The corneal center flattened by 0.038 +/- 0.05 dpt (P > 0.05) in the PRK patients and by 0.187 +/- 0.045 dpt (P < 0.05) in the control group. PRK patients within 1 year after operation showed a minimal cen tral corneal steepening,whereas PRK patients after more than 1 year sh owed a reaction similar to that in normal corneas (P < 0.05). Conclusi on: Corneal stability is altered after PRK. After 1 year corneal stabi lity seems to normalize due to stromal remodelling.