Effect of different antiglaucomatous drugs on ocular perfusion pressures

In an attempt to elucidate whether antiglaucomatous drugs, especially beta-blockers, affect systemic and/or ocular blood flow, we measured ocular perfusion pressures (PP), systemic blood pressure (BP) and heart rate in 50 healthy subjects before and after topical instillation of the following eye drops: timolol 0.5% (n = 10), betaxolol 0.5% (n = 10), carteolol 2% (n = 10), pilocarpine 2% (n = 10) and acetazolamide 750 mg per os (n = 10). The ocular perfusion pressures were measured by OODG as described by Ulrich. By means of this method--retinal and ciliary perfusion pressure can be recorded separately and simultaneously. Our results indicated that, in spite of a statistically significant decrease in IOP in all 5 groups, there was no change in retinal or ciliary perfusion pressure, heart rate or blood pressure in any of the groups except the carteolol subjects. The ocular perfusion pressures should be increased with reduction of the IOP when the systemic parameters remain unchanged. This was not the case in our experiments and therefore it can be suggested that a relative reduction in ocular perfusion pressure occurs with all agents and, in this respect, timolol and betaxolol did not affect ocular perfusion pressure more than pilocarpine and acetazolamide. Carteolol, however, produced a slight decrease (alpha less than 0.02) in ocular perfusion pressure, in spite of lowering of the IOP.