PURPOSE: To help the ophthalmologist who wishes to know the perfusion status of the retina outside the macula, we determined whether clinical examination can predict capillary nonperfusion in diabetic retinopathy (DR) as accurately as fluorescein angiography (FA). DESIGN: Prospective observational case series. METHODS: SETTING: Clinical practice. STUDY POPULATION: Both eyes of 20 patients with clinically significant diabetic macular edema (CSME). OBSERVATION PROCEDURE: The location of capillary nonperfusion was recorded following 90-diopter lens slit-lamp biomicroscopy, and the same measurements made on FA. MAIN OUTCOME MEASURE: In the nasal and temporal quadrants of each eye, the clinical results were compared with the "gold standard" FA. RESULTS: Most patients (84%) had definite peripheral capillary nonperfusion. Biomicroscopy results were highly correlated with angiography, with only a few differences of clinical importance. CONCLUSIONS: Clinical examination can determine the location of capillary nonperfusion in DR with a high degree of accuracy.