Localised scotomata and types of vascular occlusion in diabetic retinopathy

In 13 patients with diabetic retinopathy who had localised scotomata in the central visual field that could not be ascribed to haemorrhages, cotton wool spots or hard exudates, visual field data obtained by computerised perimetry were correlated with the corresponding retinal morphology as seen on fundus photographs and fluorescein angiograms. It was attempted to relate the retinal areas corresponding to the scotomata to areas of distribution from the central retinal artery. In six cases localised scotomata could be correlated with focal areas of angiographical non-perfusion in the macular area. When these areas of non-perfusion were traversed by a patient vessel, the retinal zone adjacent to this vessel was found to have retained light sensitivity. Two localised scotomata could be correlated with retinal areas peripheral from occluded arterioles, but no scotoma was found which could be related th retinal venous occlusion. In five cases scotomata occurred, however, which could not be related to areas of distribution from the central retinal artery. It is concluded that factors other than retinal vascular occlusion probably are involved in causing impairment of neurosensory function in diabetic maculopathy.