EVALUATION OF PENTOXIFYLLINE IN THE PREVENTION OF HAZE AFTER PHOTOREFRACTIVE KERATECTOMY IN THE RABBIT

BACKGROUND: Pentoxifylline (PTX) is a methylxanthine derivative that, besides its hemorrheologic properties, possesses multiple physiologic effects at the cellular level. It has been used in keloid prevention d ue to its ability to inhibit the secretion of collagen and glycosamino glycans from activated fibroblasts. METHODS: Ten New Zealand White (NZ W) rabbits underwent a -7.00 diopters, 6.0 mm diameter photorefractive keratectomy after laser ablation of the epithelium with a VISX 20/20 excimer laser. The bare stroma was stained with fresh 0.5% dichlorotri azinyl aminofluorescein (DTAF). The procedure was performed on both ey es, 4 days apart. One eye received 1% Pentoxifylline qid and the other balanced salt solution qid as a control for 4 weeks, starting the sam e day of surgery, Two masked observers graded the amount of haze at 2, 4, 6, and 8 weeks after surgery using slit-lamp biomicroscopy. Three rabbits were sacrificed at 2 and 4 weeks followed by two rabbits at 6 and 8 weeks. The area between the DTAF-stained collagen to the base of the epithelium was measured using a digital image analyzer. RESULTS: There was no statistically significant difference in the amount of haz e either by slit-lamp microscopy or by histological analysis between t he pentoxifylline-treated eyes and the controls at any time interval ( Student's t-test: 0.16 to 0.92) CONCLUSION: Pentoxifylline did not see m to affect haze formation in a PRK rabbit model. As no signs of toxic ity were observed, further studies might examine higher concentrations or dose frequencies.