Patients with diabetic retinopathy have ERGs that become more abnormal with the progression of their retinopathy. The most sensitive features of the ERG to diabetic retinopathy are the flicker ERG and oscillatory potentials (OPs). The OPs amplitude is reduced with diabetic retinopathy. The flicker ERG amplitude is reduced and the implicit time is lengthened with diabetic retinopathy. These ERG parameters are sensitive predictors of progression to high risk characteristics in eyes with diabetic retinopathy, and provide unique predictive information that supplements ophthalmoscopy and fluorescein angiography.Diabetic Retinopathy
The ERG is a sensitive and specific predictor of eyes with CRVO that will develop neovascularization of the iris (NVI) and subsequent neovascular glaucoma. A simple few minute test — the 30 Hz flicker ERG — taken the first time the patient presents with symptoms of CRVO, can predict with 93% accuracy whether the patient will develop NVI. Studies have shown that the ERG is much better at predicting outcomes in this disease than is fluorescein angiography.Central Retinal Vein Occlusion (CRVO)
The effect of carotid artery stenosis on the ERG depends upon the extent and severity of the occlusion, and the amount of collateral circulation that has developed through the circle of Willis and the external carotid artery. As the eye becomes more ischemic, developing venous stasis retinopathy, a-wave and b-wave amplitude and timing are significantly affected, and the 30 Hz flicker response is notably delayed.Stenosis of the Carotid Artery
In patients with sickle-cell retinopathy in the absence of peripheral retinal neovascularization, ERG the a-wave and b-wave have normal amplitude and timing, and oscillatory potential amplitudes are normal. If peripheral retinal neovascularization is present, all ERG components are reduced in amplitude.Sickle Cell Retinopathy
