The effects of panretinal photocoagulation (PRP) on intravitreal proliferation were evaluated in an experimental model for proliferative vitreoretinopathy (PVR). Thirty-three pigmented rabbits underwent argon laser PRP in one eye. Cultured fibroblasts (2 x 10(5) or 4 x 10(5) cells) were implanted into the intact vitreous of both eyes of each animal either 3 days after PRP (when acute laser lesions were present) or 4 weeks after PRP (scarred laser lesions). PVR was assessed by indirect ophthalmoscopy for 4-8 weeks. Histological examination included staining with monoclonal antibodies against glial fibrillary acidic protein (GFAP). In both groups significantly more severe stages of PVR developed after PRP than in the controls. Total retinal detachments ensued in 13 photocoagulated eyes versus five controls. PRP induced invasion of macrophages, proliferation of retinal pigment epithelium and a conspicuous Müller cell response, enhancing intraocular inflammation, which stimulated intravitreal proliferation and aggravated PVR.