In 19 patients with bilateral proliferative diabetic retinopathy we examined the blood velocity in the ophthalmic artery with pulsed ultrasound and analyzed the outline of the pulse curve with the fast fourier transformation. The data were compared with the results in 50 normal objects. Patients with diabetic proliferative retinopathy showed increased systolic blood velocities (p less than 0.05), decreased diastolic blood velocities (p less than 0.05) and an alteration in the outline of the pulse curve (p less than 0.001). These changes can be due to diabetic-induced decrease in the elasticity of the wall of the ophthalmic artery and to microangiopathic alterations in the choroid. In some patients in the course of the ophthalmic artery, we saw localized peaks in the blood velocity, which can be interpreted as local stenosis in the ophthalmic artery.