Effect of topical betablockers on human retinal vessels diameters

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Abstract
Purpose: To measure the effect of topicalbetaxolol 0.5% and timolol 0.5% on retinal vesselsdiameters by means of photographic enlargment.Methods: Thirteen glaucomatous patients(primary open angle glaucoma (POAG) and ocular hypertensive (OH)) were treatedtwice daily with betaxolol 0.5% for one year.These same patients were subsequently treated with timolol 0.5% during the following year. Fundus photographs were taken with Canoncamera 30 ° angle at baseline and two hours afterinstillation at 3, 6 and 12 months of treatment for each drug.The diameters of the superior and inferiortemporal vessels (arteries and veins) were measured at one and two discradii from the margin of the disc using photographicenlargment (× 66.7) of the right eye and were analysed under double masked fashion during the same session.Results: A significant increase of the meanarterial diameter (+ 7.4% p = 0.000 paired t) was found after 12months of betaxolol treatment, while no persistent further difference (+ 1.3% NS) was found after 12 months of timolol treatment.No modification was found in venous diameter.Conclusion: Betaxolol treatment isassociated with a beneficial effect on retinal arterieswidth whereas Timolol does not yield the same amplitude of benefit.