Evaluation of the tourniquet test as a predictor of diabetic retinopathy.

Medical practitioners often have difficulty in assessing the presence or severity of diabetic retinopathy. The tourniquet test is a method of assessing diabetic capillary fragility that has been felt to reliably correlate with background and proliferative diabetic retinopathy. We studied 100 consecutive diabetic patients and 50 age-matched controls in a masked fashion, using fundus photographs and fluorescein angiography to correlate the amount of capillary fragility with the presence and severity of background and proliferative diabetic retinopathy. Although the severity of diabetic capillary fragility did correlate with the presence and severity of diabetic retinopathy (p less than 0.001), this test was not as good an indicator of diabetic retinopathy as were other risk factors such as duration of diabetes (p much less than 0.001). The tourniquet test is unreliable in predicting the presence or severity of diabetic retinopathy because of its high false negative response rate.