Abstract

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 HTP_D (20.2 (0.5)/16.3 (0.5)) and in CTL_D (16.0 (0.5)/12.3 (0.5)) was highly significantly (p <0.001) reduced and was significantly (p<0.03) reduced in vehicle (V) treated eyes (HTP_V: 20.3 (0.4)/19.0 (0.4)) and CTL_V: 15.8 (0.4)/14.9 (0.3)) when compared with respective baseline measurements. OPA (mm Hg) in HTP_D (2.1 (0.1)/2.5 (0.1)) and CTL_D (2.2 (0.1)/2.6 (0.2)) eyes was significantly (p<0.05) increased and unaffected in vehicle treated eyes when compared with respective baseline measurements. Systemic perfusion variables were also unchanged.

CONCLUSION Dorzolamide increased OPA in HTP and CTL. Drugs stimulating OPA may improve prognosis of POAGs.