Primary open-angle glaucoma patients characterized by ocular vasospasm demonstrate a different ocular vascular response to timolol versus betaxolol

We evaluated the retrobulbar response to a selective versus nonselective be ta blocker in a subgroup of primary open-angle glaucoma patients (POAG) cha racterized by ocular vasospasm. Eleven patients who exhibited ocular vasosp asm (i.e. a significant increase in ophthalmic artery blood flow velocity o r a significant decrease in ophthalmic artery resistance index during hyper capnia) underwent medication washout for 4 weeks and were enrolled in a dou ble-masked cross-over study (betaxolol versus timolol). Patients were evalu ated for blood flow velocity of the retrobulbar vessels using color Doppler imaging, intraocular pressure, visual field sensitivity and contrast sensi tivity at the beginning and end of each 4 week treatment period. Timolol treatment caused a significant reduction in IOP (p = .007), but no change in retrobulbar hemodynamics or visual function. After betaxolol trea tment, resistance index fell significantly (p = .040) in the ophthalmic art ery and increased significantly in both the central retinal (p = .003) and temporal posterior ciliary arteries (p = .030). Also following betaxolol tr eatment, contrast sensitivity improved significantly (p = .006), and a sign ificant positive correlation was shown between change in contrast sensitivi ty and change in resistance index (r = .70; p = .015) of the ciliary arteri es. POAG patients characterized by ocular vasospasm display a significant h emodynamic response to betaxolol, but not to timolol.