Color Doppler imaging study in patients with primary open-angle glaucoma treated with timolol 0.5% and carteolol 2%

To evaluate with color Doppler imaging (CDI), in patients with primary open-angle glaucoma (PDAG), the possible influence on ocular hemodynamics of a beta-blocking agent with intrinsic sympathomimetic acitivity (carteolol 2%) compared to a beta-blocker agent without this activity.

A study was carried out on 20 patients, with bilateral POaG, intraocular pressure (IOP) < or = 20 mmHg, all treated twice a day with timolol maleate 0.5% ophthalmic solution. The visual field was evaluated (Octopus 2000 perimeter, G1 program) examining the mean sensitivity (MS) and the mean defect (MD). CDI was carried out to evaluate the resistance index of the internal carotid artery (ICA), the ophthalmic artery (OA), the central retinal artery (CRA), and the short posterior ciliary arteries (SPCA). After these examinations, the therapy was changed to carteolol 2% twice a day. After six months of treatment the examinations were repeated. The data were analysed statistically using Student's t test.

The mean intraocular pressure during treatment with timolol 0.5% was 16.7 +/- 1.67 mmHg and 16.33 +/- 1.72 mmHg after treatment with carteolol 2%, the difference not being significant (p=0.494). After six months of treatment with carteolol 2% the MS increased significantly from 22.4 +/- 2.5 dB to 24.1 +/- 1.8 dB (p=0.018), and the mean defect (MD) fell from 5.3 +/- 0.8 dB to 4.7 +/- 0.6 dB (p=0.011). There was no significant difference in the resistance index of the CA, the OA and the CRA with the two treatments, whereas the resistance index of the SPCA dropped significantly, from 0.80 +/- 0.05 to 0.77 +/- 0.02 (p = 0.017).

CDI did not show significant differences in the resistance indexes of the internal CA, the OA, and the CRA after treatment with carteolol 2% but the resistance index of the SPCA was significantly reduced. Carteolol 2% induced significant changes in the perimetric indexes examined, with an increase in MS and a decrease in MD. These findings suggest that the intrinsic sympathomimetic activity of carteolol may reduce peripheral vascular resistance of the SCA, thus improving perfusion of the optic nerve head, with a protective effect on visual function.