PURPOSE:To evaluate the activitv of protein kinase C(PKC) in response to retinal photochemical insult in rat. Furthermore, to investigate the effect of dexamethasone(DXM ) on PKC activity. METHODS :The experiments were performed on 48 SI') rats whieh were separated into two groups,control and treated groups,and the latter received daily intraperitoneal injections of DXM (1 mg/kg)for 5 consecutive days,starting 3 days before light exposure. The animals were continually exposed to green fluorescent light (510nm~560nm) with an illuminance level of (1 900plusmn;106.9)lx for 24 hrs.The retinal enzyme activity of PKC was tested at 6 hrs,1 day,3 days,7 days,and 14 days after light exposure respectively. RESULTS:In animal models,PKC activity showed a transient increase in both groups at 6 hrs after light exposure and then decrease persistently there alter. The activity of PKC was unresponsive to DXM intervention. CONCLUSIONS :These results suggested that the persistent lower PKC activity might result in disturbance of retinal function in rat retinal photochemical injury. （Chin J Ocul Fundus Dis,1997,13: 78-80）