To assess the change of nitric oxide(NO) concentration according to photorefractive keratectomy(PRK) depth and the role of NO in cataractohenesis after excimer laser PRK. The treated 36 rabbits were divided into 12 groups according to PRK depth(-3.0, -7.0, -11.0 diopter [0]), the dates of sampling(the 1st day and the 7th day after PRK), and reatment of NOS inhibitor (NG-nitro-L-arginine methylester, L-NAME). NO concentration and superoxide dismutase(SOD) activity in the aqueous humor and malondialdehyde(MDA) concentration in the lens were measured. Changes of lens epithelium were examined by eletron microscopy on the 3rd day and the 6th day after -11.0D of PRK. The NO and MDA concentration in the group without L-NAME treatment on the 1st day after -11.0D of PRK were significantly higher than those in the L-NAME treated group and control group. The activity of SOD increased in all of the PRK treated group on the 1st day and was even higher on the 7th day. The histopathological changes of lens epithelium on the 3rd day after PRK were compatible with cellular necrosis and those of the 6th day after PRK were compatible with cellular reparing. The results suggested that the toxicity of NO after PRK correcting over -11.0D may a role in cataractogenesis, but the progress could be suppressed by treatment of NOS inhibitor.
Aqueous Humor ; Epithelium ; Lasers, Excimer ; Malondialdehyde ; Microscopy ; Necrosis ; NG-Nitroarginine Methyl Ester ; Nitric Oxide* ; Photorefractive Keratectomy* ; Rabbits ; Superoxide Dismutase ; Superoxides