The effects of methylprednisolone on laser induced retinal injuries

Methylprednisolone have been demonstrated to ameliorate retinal photic injury. In the current study we examined its effect on laser induced retinal injury. Retinal lesions were inflicted by argon laser (0.05 W, 0.1 sec, 200 micrometer) in 36 pigmented DA rats. The treated groups received intra-peritoneally methylprednisolone (160 mg/kg) in saline, injected 3 times a day for 2 days, starting immediately after exposure. The controls received the vehicle on the same schedule. The rats were sacrificed 3, 20 or 60 days after laser exposure and the lesions were evaluated by light microscopy and morphometric measurements. Laser injuries were associated with disruption of the outer retinal layers. Three and 20 days after exposure, the loss of the photoreceptor-cell nuclei was significantly milder in the treated groups as compared with controls (39. 1 Vs 55.3% loss, treated and control respectively, 20 days after exposure p=0.00008). There was no difference 60 days after exposure. In conclusion, methylprednisolone reduced temporarily the photoreceptor cell loss in argon laser induced retinal injury, when treatment was started immediately after laser exposure. There was no long term effect.