ALTERATIONS IN BLOOD-AQUEOUS BARRIER AFTER CORNEAL REFRACTIVE SURGERY

Purpose. To assess alterations in the blood-aqueous barrier after radi al keratotomy (RK), photorefractive keratectomy (PRK), laser in situ k eratomileusis (LASIK), and phototherapeutic keratectomy (PTK). Methods . Aqueous flare was evaluated using the Kowa FM 500 laser flare meter in a total of 87 eyes from 82 patients who underwent refractive surger y. Measurements were obtained preoperatively in 51 eyes of 51 patients who underwent RK or PRK and again at the end of surgery, and at 1 day and 1 week postoperatively. These patients had been randomized (doubl e masked) to receive topical 0.1% dexamethasone, polymyxin B (6,000 U/ ml), and 0.5% neomycin 4 times a day for 1 week after surgery, or poly myxin B (6,000 U/ml) and 0.5% neomycin for 1 week. Aqueous flare measu rements were also obtained before surgery in 36 eyes (31 patients) tha t underwent LASIK and again at 1 day and 1 and 2 weeks postoperatively . All patients in this group received topical 0.1% dexamethasone, poly myxin B (6,000 U/ml), and 0.5% Neomycin 4 times a day for 15 days afte r surgery. Results. Uneventful RK induced a significant increase in fl are immediately after surgery, although this did return to baseline 1 day after surgery (Friedman test). Measurements at 7 days after surger y were similar in steroid-treated and untreated groups. Limbal bleedin g, which occurred in 23% (12/51) eyes, did not induce significantly in creased flare as compared to uneventful RK. Microperforations, which o ccurred in 18% (9/51) eyes, did induce significant alterations in the blood-aqueous barrier that persisted for >1 day, but measurements retu rned to preoperative levels by day 7. PRK and LASIK induced substantia lly increased flare in some eyes. Phototherapeutic keratectomy, in par ticular, induced an elevation in flare measurements that did not retur n to normal levels even by 15 days after surgery (Friedman test). Conc lusions. Using mean results of laser flare meter evaluation, uneventfu l RK appears to induce short-lasting elevations in aqueous flare in bo th steroid-treated and untreated patients. Microperforation induced pr ominent alterations in flare measurements, although limbal bleeding di d not. Both PRK and LASIK did appear to increase flare measurements in some eyes, while PTK induced significant elevations in aqueous flare in the majority of eyes.