Comparison of intraocular treatment of DMTU and SOD following retinal ischemia in rats

The effect of intravitreal injections of DMTU (dimethylthiourea) and SOD (s uperoxide dismutase), two free radical scavengers, was evaluated in a rat m odel of retinal ischemia induced by elevated intraocular pressure. The drug s were administered just before or just after a 60 min ischemia. At days 2 and 7 after reperfusion, retinal recovery was evaluated by electroretinogra phy. At day 7, layer thicknesses and cell rows were measured from histologi c sections of paraffin-embedded retinas. In the vehicle-treated control gro up, we observed a decrease in the inner retinal layers and b-wave amplitude impairment. SOD injection (6 units/eye) protected the retina from ischemia /reperfusion injury. At day 2 after reperfusion, electroretinographic recov ery was more efficient when SOD was administered just after ischemia (99%) than after pretreatment with SOD (81%) (p<0.03). In the DMTU-treated group (75 mu g/eye), only the pretreatment induced significant electrophysiologic (40%) (p<0.001) and morphologic recovery.