Doppler ultrasonography of the central retinal artery in normals treated with topical timolol.

Using high-resolution Duplex scanning it is possible to evaluate the blood flow velocity in the central retinal artery of eyes of normal individuals. The flow velocity can be divided into its systolic and diastolic phases. Topical timolol maleate 0.5%, a non-selective beta-adrenergic receptor blocking agent, was then administered to one eye in each of the normals and the flow velocity was again recorded. The flow velocity improvement was significant, with a 43.58% increase in the systolic phase and a 61.53% increase in the diastolic phase. The diastolic component increased from 49.29% to 55.56%. The increased flow velocity may be due to a vasodilatory effect of timolol. The technique is briefly described and the significance of the results discussed.