THE EFFECTS OF TOPICAL CORTICOSTEROIDS AND PLASMIN INHIBITORS ON REFRACTIVE OUTCOME, HAZE, AND VISUAL PERFORMANCE AFTER PHOTOREFRACTIVE KERATECTOMY - A PROSPECTIVE, RANDOMIZED, OBSERVER-MASKED STUDY

Background: This study of 86 patients with 12 months of follow-up was designed to determine whether topical corticosteroids or plasmin inhib itors have an effect on the outcome of photorefractive keratectomy. Me thods: Patients were allocated randomly to either steroid (0.1% fluoro metholone for 6 months), plasmin-inhibitor (aprotinin 40 IU/ml for 3 w eeks), or control (no treatment) groups and underwent either -3.00- or -6.00-diopter (D) corrections. Results: With -3.00-D corrections, the mean refractive change was significantly greater at 3 and 6 months (P < 0.05) in the steroid group compared with the control group. When st eroids were discontinued, the difference became insignificant within 3 months. Similarly, with -6.00-D procedures the mean refractive change was greater at 6 weeks and 3 and 6 months (P < 0.01), but the refract ive change again became insignificant 3 months after stopping steroid treatment. Four patients treated with steroids had a hyperopic shift g reater than +2.00 D of that intended at 12 months. Similar overcorrect ions were not noted in the other treatment groups. There were no diffe rences in refractive outcome between the aprotinin and control groups at any stage. With -6.00-D procedures, objective measurements of haze were significantly greater in the aprotinin group compared with the co ntrol group at 9 and 12 months (P < 0.05). With this exception, there were no differences in haze, forward or backward scatter of light, bes t-corrected visual acuity, or halo measurements between the groups. Co nclusions: Corticosteroids can maintain a hyperopic shift during their administration, but this effect is reversed on cessation of treatment . Objective tests have shown that steroids have no effect on corneal h aze or visual performance after PRK. There is no justification for rou tinely submitting all patients to long-term steroid regimens and their associated side effects. Treatment with aprotinin produced no benefic ial effect on refractive outcome, and haze was greater in the -6.00-D procedures. The concept of modulating the plasminogen activator/plasmi n system to regulate wound healing after PRK is discussed.