AIM: To study the pathogenesis of transient intraocular pressure(IOP)after laser iridectomy with Krypton laser combined with Q-switched Nd:YAG laser.

METHODS: Totally 42 healthy rabbits(84 eyes)provided by the Animal Experimental Center of our hospital were selected, including 18 female rabbits, 24 male rabbits, average weight 2.24±0.31kg, and they were randomly divided into 6 groups, 7 rats in each group(14 eyes). We observed the change of intraocular pressure after laser iridectomy surgery at 20min, 2, 6, 18, 24h and the nitric oxide(NO), malondialdehyde(MDA), superoxide dismutase(SOD), 6-keto-prostaglandin(6-keto-PGF1α)and nitric oxide synthase(NOS)content in aqueous.

RESULTS: There was no significant difference in intraocular pressure, NO, NOS, SOD, MAD and 6-keto- PGF1α before operation(P>0.05). The intraocular pressure increased after operation, and the difference was statistically significant(P<0.05)at 20min, 2 and 6h after operation, and decreased at 18h after operation, 24h after operation(P>0.05). The levels of NO, NOS and SOD in the aqueous humor of the two groups decreased 20min, 2 and 6h after the operation(P<0.05), while increased after 6h, increased more at 18 and 24h.The difference with control group was no more significant(P>0.05). The levels of MDA and 6-keto-prostaglandin in the aqueous humor increased after the operation, and the difference was statistically significant at 20min, 2 and 6h after operation(P<0.05), while decreased at 18 and 24h and the difference with control group was not significant(P>0.05).

CONCLUSION: The increase of transient intraocular pressure after laser iridectomy may relate to the increase of malondialdehyde, 6-keto-prostaglandin content and the decrease of superoxide dismutase and nitric oxide in the aqueous humor after operation.