Pindolol and timolol: short-term influence on angioscotomas and static brightness contrast sensitivity.

In a double-masked, short-term study on 12 healthy elderly volunteers, angioscotomas and contrast sensitivities were measured 2 h after treatment with placebo, pindolol 1% and timolol 0.5%. In perimetry, angioscotomas did neither change in deepness nor in diameter significantly. However, the mean differential light sensitivity was highest with timolol (15.5 dB) and lower with pindolol (15.2 dB p less than 0.018) and placebo (15.0 dB; p less than 0.004). In contrast sensitivity testings, the mean contrast sensitivity was lowest with timolol (15.0 dB) and higher with pindolol (15.3 dB p less than 0.001) and placebo (15.7 dB; p less than 0.001). The differences between pindolol and placebo were not significant in both tests. The contrasting results may be explained by the locations where retinal sensitivity was tested, near or far from retinal vessels i.e. foveally or near the blind spot. Pharmacologically, the main difference between the two medications is the intrinsic sympathomimetic activity of pindolol.