Therapy of normal tension glaucoma: effect of brinzolamide on ocular haemodynamics

BACKGROUND: Altered ocular perfusion plays a role in the pathophysiology of normal tension glaucoma. Dorzolamide, a locally applied inhibitor of carbonic anhydrase, is thought to increase ocular blood flow. Less data are available regarding the influence exercised on ocular perfusion by brinzolamide, another and different, locally administered, inhibitor of carbonic anhydrase. PATIENTS AND METHODS: n = 15 eyes of 8 normal tension glaucoma patients were subjected to colour Doppler imaging and Langham-OBF (LOBF) before and during a therapy for 3 - 5 weeks with brinzolamide. RESULTS: Brinzolamide reduces intraocular pressure from 15.8 +/- 0.9 to 12.6 +/- 0.9 mm Hg (n = 15; P < 0.05). Systolic as well as diastolic blood flow velocities, resistive (RI) and pulsatility index (PI), measured by CDI, remained unchanged in the presence of brinzolamide. LOBF values are also not influenced by brinzolamide (1014 + 115 before vs. 1113 +/- 178 microl under therapy; n = 15; n. s.). DISCUSSION: Brinzolamide does not exercise any impact on ocular haemodynamics. This is different from the properties of dorzolamide that had been reported previously.