ARF 193NM EXCIMER-LASER CORNEAL SURGERY AND PHOTOOXIDATIVE STRESS IN AQUEOUS-HUMOR AND LENS OF RABBIT - ONE-MONTH FOLLOW-UP

Twenty male albino rabbits were studied. Four animals served as contro ls; the remaining 16 animals represented the treated group. All the tr eated animals were exposed to the same amount of energy delivered by t he excimer laser (pulse rate: 20 Hz, fluence 250mJ/cm(2); number of pu lses: 6032; cumulative UV dose 1508 J/cm(2)) and were divided into eig ht groups of 2 animals each (four eyes). Samples of aqueous humor and lens were obtained at the following intervals: 5, 10, 20 and 40 min an d 1, 2, 3 and 4 weeks after photorefractive keratectomy (PRK). The lev els of reduced and oxidized glutathione, hydrogen peroxide, ascorbic a cid and malondialdehyde were determined. Aqueous humor analyses, twent y min after PRK, showed no significant differences with pre-treatment values, while the observed variations in lens were constantly present over the entire follow-up period (one month). These findings suggest t hat the biochemical lens alterations induced by PRK may represent the earliest events relevant to cataractogenesis in the rabbit.