We studied 40 patients, 25 males and 15 females, aged between 53 and 68 years (mean 63.4) with chronic simple open-angle glaucoma. The patients were divided in a random, double-blind manner into two groups. Group A was administered a non-selective beta-blocker (Timolol maleate 0.5%) twice a day. Group B was administered a non-selective drug with intrinsic sympathomimetic activity (Carteolol 2%). All the patients were examined with an Color Doppler Imaging (CDI) of the ophthalmic artery (OA) and the posterior ciliary arteries (PCA's) and computerised perimetry before starting treatment and after one year of treatment. CDI was performed using an Asynchronous-Hitachi ecograph with a 7.5 MHz linear probe. The visual field examination was performed with a Humphrey 740 perimeter and the 30.2 Full Threshold program.

Statistical analysis was performed, using the Student t test for paired and unpaired data, on the variations in the peak systolic velocity (PSV) and the resistance indices (RI) in the vessels studied with Color Doppler imaging as well as the MD and the CPSD of computerised perimetry

The results are summarized in Table 1.

	controls	Timolol Maleate	P<0.05	Carteolol	P<0.05	P<0.05*
IOP	23.200± 1.1764	14.200±3.033	0.012	15.400±3.507	0.027	0.070
PSV OA	32.360±3.902	31.740±5.764	0.862	37.680±3.569	0.239	0.082
RI OA	0.740±0.031	0.730±0.042	0.294	0.666±0.064	0.078	0.143
PSV PCA’s	12.570±1.943	14.960±2.759	0.290	14.380±1.690	0.173	0.668
RI PCA’s	0.643±0.106	0.572±0.061	0.833	0.422±0.038	0.050	0.005
MD	-6.073±3.128	-8.822±3.478	0.006	-2.658±2.476	0.048	0.002
SF	1.856±0.949	2.947±0.987	0.044	2.336±1.035	0.370	0.199
CPSD	4.527±1.328	4.779±1.851	0.778	1.678±3.105	0.039	0.002

*comparision between Timolol maleate and Carteolol

Tab 1 – Statistical assessment of the variation in the the perimetric and flow indeces after topical treatment with Timolol maleate and Carteolol.

This study revealed how a good pressure compensation is obtained with Carteolol even if the tonometric values were slightly higher than the control group. The reduction in ocular pressure is accompanied by a reduction in the resistance indices for the posterior ciliary arteries with statistically significant improvement in the perimetric indices as compared with the group treated with Timolol maleate, where there was a progressive worsening. The significant reduction in the PCA's resistance indices in the group treated with Carteolol can be linked to the drug interaction with the vessel endothelium. This leads to intraluminal release of vasodilating prostacyclins, as well as the extraluminar release of vasodilating endothelial factors (in particular nitric oxide) as a result of the activation of the alpha-2 adrenergic receptors (7).

We believe that Carteolol, although it has a similar pressure-reducing effect to Timolol maleate, is also a drug which is effective in blocking glaucomatous optic neuropathy, reducing the posterior ciliary artery resistance and thus improving circulation at the head of the optic nerve.

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