Changes in the electroretinogram of eyes with diabetic retinopathy treated by vitrectomy

Flash electroretinogram (ERG) and 30 Hz flicker ERG before and after operation were tested in 55 eyes of 46 patients with proliferative diabetic retinopathy who were treated by vitrectomy. The results were evaluated with preoperative ocular findings -the existence of retinal detachment, posterior vitreous detachment, panretinal photocoagulation (PRP) and vitreal hemorrhage and intraocular tamponade materials. In the group without retinal detachment, the amplitude of the ERG b-wave and a-wave after vitrectomy decreased significantly if PRP was not done before operation. In the group with retinal detachment, when retinal detachment was restricted to the posterior pole of the fundus, when posterior vitreous detachment had occurred in only a small area of the fundus, when there was vitreous hemorrhage or when silicone oil was injected in the operation, the amplitude of the ERG b-wave and a-wave decreased significantly after the operation. In both groups, the latency of 30 Hz flicker ERG was shortened significantly after vitrectomy.