Topical carbonic anhydrase inhibition increases ocular pulse amplitude in high tension primary open angle glaucoma

BACKGROUND Ocular pulse amplitude (OPA) is reduced in normal tension primary open angle glaucoma (NTP) patients when compared with healthy age matched controls (CTL) while increased OPA appears to protect ocular hypertensive patients from visual field loss. If NTP is accompanied by vasospasm, as in roughly half of the primary open angle glaucoma (POAG) population (independent of intraocular pressure, IOP), calcium channel blockers increase OPA and thus stabilise visual fields in these patients. Current glaucoma drugs reduce IOP but do not activate (compromised) ocular perfusion. METHODS The influence of dorzolamide, a topical carbonic anhydrase inhibitor in standard dosage (three times daily, one eye) on OPA, IOP, blood pressure, and heart rate was investigated in a randomised, prospective, masked clinical trial assessing the acute effects of dorzolamidev placebo before and 2 days after application in 33 cataract patients with (n = 14) and without (n = 19) high tension POAG (HTP) who provided informed consent. RESULTS Following application of dorzolamide (D) IOP (mm Hg, mean (SEM)) in HTPD (20.2 (0.5)/16.3 (0.5)) and in CTLD (16.0 (0.5)/12.3 (0.5)) was highly significantly (p