Colour Doppler ultrasonography of the ophthalmic artery: flow parameters in normal subjects. The significance of the resistance index.

Abstract

When an inversion of the ratio between the resistance index of the ophthalmic artery and that of the common carotid or an index value lower than 0.70 in the ophthalmic artery is observed, further investigation is needed as this situation cannot be considered normal. The resistance index seems to be the most reliable parameter for the estimation of normal circulation in ophthalmic arteries.