Influence of instillation of carbonic anhydrase inhibitors on the circulation in the optic nerve head

Purpose: To report the effect of instillation of carbonic anhydrase inhibitors on the circulation of optic nerve head in healthy adults. Cases and Method: This study was made on 10 healthy humans between 24 and 56 years of age. Five cases received daily instillation of 1% dorzolamide in one eye. The other 5 cases received daily instillation of 1% brinzolamide. The fellow eyes received physiological saline and served as control. Laser speckle method was used to quantitate the blood flow velocity in the artery, vein and microcirculation in the optic nerve head. Square blur rate (SBR) served as indicator of blood flow velocity before and after 2 weeks of instillation. Results: There was no significant difference in the circulation of optic nerve head before and after 2 weeks of instillation of dorzolamide or brinzolamide when compared with the fellow eye. Conclusion: Daily instillation of dorzolamide or brinzolamide for 2 weeks does not significantly influence the circulation in the optic nerve head in healthy adults when measured by laser speckle method.