Changes in retrobulbar ocular hemodynamics and visual function in low tension glaucoma patients after six months of treatment with nifedipine

Purpose. Reduced ocular blood flow, possibly from ocular vasospasm, has been suggested as a cause for vision loss associated with normal-tension glaucoma (NTG). Calcium channel blocking agents have recently been proposed as treatment for ocular vasospasm. Methods. Color Doppler imaging (CDI) of the ophthalmic, central retinal and short posterior ciliary arteries, visual field sensitivity and static spatial contrast sensitivity were evaluated for sixteen NTG patients (9 Female/ 7 Male: Age 58.8 ± 15 years) after 3 weeks of drug washout and again following 6 months of treatment with nifedipine. Results. Nifedipine did not alter IOP, blood pressure or heart rate. The drug left peak systolic velocity, end diastolic velocity and resistive index in each retrobulbar vessel unaltered. Visual field sensitivity and contrast sensitivity (CS) at 3 spatial frequencies also showed no change. CS did, however, improve significantly at 6 cpd (p = .004). Within the 16 patients, regression analysis revealed an apparent association between drug induced changes in CS (r = .81, p<.001) and ophthalmic artery indices and between visual field sensitivity (r = -.55, p < .05) and central retinal artery resistive index. A significant correlation between age (r = -.64, p < .01) and ophthalmic artery indices was also noted at baseline. Conclusions. Nifedipine did not provide universal benefit for improving ocular blood flow velocity in NTG patients. Drug induced changes in ocular blood flow velocity may be related to changes in certain measures of visual function in some patients.