Changes in optic nerve head blood flow induced by the combined therapy of latanoprost and beta blockers

Abstract

To assess the effects of combined therapy with latanoprost and beta blockers on optic nerve head (ONH) blood flow in normal-tension glaucoma (NTG) patients. Intraocular pressure (IOP), ONH blood flow (laser speckle flowgraphy) and blood pressure were measured in 15 eyes of 15 NTG patients (41-76 years old) before treatment or after a 1-month washout period. Similar measurements were performed at 2 months after the commencement of treatment with latanoprost and at 3 months after the start of combined therapy of latanoprost with 0.5% timolol or 2% carteolol in a crossover study using the envelope method. Measurement was carried out 2-3 hr after the morning application of eyedrops. Latanoprost decreased IOP with no significant change in ONH blood flow. Concomitant use of timolol or carteolol further decreased IOP with no significant difference between these two drugs. Only the combined therapy of latanoprost with carteolol significantly (p < 0.01) increased ONH blood flow by approximately 10%, compared to initial levels. There was no significant change in mean blood pressure, ocular perfusion pressure or pulse rate as a result of these therapies. Topical latanoprost-carteolol combined therapy increased ONH blood flow in NTG patients, unlike latanoprost-timolol therapy. Because ocular perfusion pressure was unchanged, direct vasodilative effects were suspected as the mechanism.