Intraocular pressure reduction with topically administered pilocarpine, timolol and betaxolol in normal tension glaucoma.

The IOP-lowering effect of topical glaucoma medication has been studied mainly in eyes with ocular hypertension or high tension glaucoma. We tested the IOP-lowering effect of the commonly used topical medications (pilocarpine, timolol and betaxolol) in eyes with normal tension glaucoma. Instillation of 2% pilocarpine hydrochloride three times a day had no statistically significant lowering effect on the IOP level (F test, P = 0.0596, n = 18). 0.5% timolol maleate administered twice a day (n = 16) and 0.5% betaxolol hydrochloride administered twice a day (n = 17) led to statistically significant lowering of the IOP level (F test, P < 0.0001 for timolol and P = 0.0001 for betaxolol). There was no statistically significant difference in IOP-reducing effect whether topical IOP-lowering medication had been used previously or not. The results for 11 eyes participating in all three tests were similar to the results for the other eyes in the three test groups.