Effect of topically applied 2% pilocarpine and 0.25% demecarium bromide on blood-aqueous barrier permeability in dogs

Abstract

The effect of topically applied 2% pilocarpine and 0.25% demecarium bromide on aqueous humor flare was evaluated while treating normal eyes of dogs 3 times daily for 8 days. Fifteen clinically normal Beagles were allotted to 2 drug treatment groups, and flare was measured, using laser flaremetry. Pilocarpine caused an increase of flare to 167 photon counts (pc)/ms at 7 hours, compared with the nontreated control eye mean value 3.7 pc/ms. By 31 hours, flare had decreased to 70 pc/ms with 3 daily topical treatments. By 55 hours, the flare measurement was in the normal range. Intraocular pressure (IOP) decreased in the treated eyes, compared with the nontreated eyes, and maximal decrease in IOP was observed at the same time as maximal flare. Demecarium induced a similar increase in flare and decrease in IOP, with peak effect seen at 31 hours. At that time, the flaremetry result was 28 pc/ms, compared with 3.4 pc/ms in the nontreated control eyes. After 8 days of 3 times daily treatment, flare values had returned to normal in eyes of dogs in both treatment groups. The transient increase in aqueous humor protein concentration did not result in ocular or visual damage, and long-term changes were not seen. The amount of flare increase attributable to topical application of pilocarpine was greater than the increase in human eyes when measured by use of laser flaremetry.