In six eyes we found typical signs that could serve as criteria for the differentiation of ischemic from non-ischemic retinal branch vein occlusion. Perimetry showed a mean defect (in the affected area) of more than 10 dB in eyes with defects in the retinal nerve fiber layer in contrast with 5 dB on one eye without nerve fiber defects. Secondly, fluorescein angiography showed ischemic areas in all eyes examined with localized defects in the photographs of the retinal nerve fiber layer. Damage of the retinal nerve fiber layer was observed before capillary obliteration could be detected by fluorescein angiography. Thirdly, semiquantitative optic disc morphometry demonstrated that using the difference between pallor and excavation as the only sign in ascending optic atrophy is not always useful. Fourthly, photography of the retinal nerve fiber layer showed that there is no correlation between the extension of the ischemic area and the sector angle of the defect of the retinal nerve fiber layer. Photography of the retinal nerve fiber layer can differentiative ischemic from non-ischemic retinal branch vein occlusion because of the qualitative detection of localized retinal nerve fiber layer defects. Consequently, this method is not only of great clinical importance for the diagnosis of different optic lesions, but is also useful for the prognosis and management of occlusion of the retinal branch vein.