Antioxidants reduce corneal light scattering after excimer keratectomy in rabbits.
OBJECTIVE
Excimer laser-corneal tissue interaction liberates highly reactive free radicals. Our aim was to determine if intraoperative application of antioxidants reduces the postoperative corneal light scattering by minimizing free radical-mediated cellular injury.


METHODS
Phototherapeutic keratectomy (PTK) was performed in 20 rabbit eyes. Following 40-microns epithelial ablation, rabbits were divided into two groups and received 1-minute intraoperative application of either 50% dimethyl sulfoxide and 1% superoxide dismutase or vehicle (balanced salt solution) only. This was followed by a 6-mm diameter 100-microns PTK. Corneal light scattering was measured for 18 weeks using scatterometry. A light scattering index (SI) ranging from 0-10 was calculated; SI = 1 represents normal scattering. Light microscopic examination was performed in selected corneas.


RESULTS
The mean baseline SI was similar for both groups (P = 0.95). Corneal haze followed a pattern of gradually increasing to peak at 2-3 weeks, and regressing partially thereafter. The decrease in mean SI following antioxidant application (dimethyl sulfoxide and superoxide dismutase) as compared to control group approached significance at 3 weeks (0.1 > P > 0.05) and was highly significant at 9 weeks (P < 0.05).


CONCLUSIONS
Intraoperative application of antioxidants decreases light scattering following excimer keratectomy in rabbit corneas. UV-induced free radicals may play a role in the pathogenesis of corneal light scattering following excimer laser keratectomy.
Jain
S
S
Wilmer Institute, Johns Hopkins University, Baltimore, Maryland 21287-9233, USA.
Hahn
T W
TW
McCally
R L
RL
Azar
D T
DT
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D003315:Cornea / Q000473:pathology / Q000601:surgery*; D003318:Corneal Opacity / Q000473:pathology; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D005609:Free Radicals; D007646:Keratotomy, Radial; D053685:Laser Therapy / Q000295:instrumentation*; D008027:Light; D018613:Microscopy, Confocal; D009883:Ophthalmic Solutions; D011817:Rabbits; D017382:Reactive Oxygen Species / Q000378:metabolism; D012542:Scattering, Radiation; D013482:Superoxide Dismutase / Q000494:pharmacology; D014945:Wound Healing / Q000187:drug effects
D000975:Antioxidants; D005609:Free Radicals; D009883:Ophthalmic Solutions; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase; D004121:Dimethyl Sulfoxide