Effect of vehicle on pilocarpine-induced miosis.

To determine the effect of 1.4% polyvinyl alcohol (PVA) and castor oil vehicles on the pilocarpine-induced miosis, we studied the miotic effect of 2% pilocarpine-PVA and oily drops on 4 young and 10 elderly people and the miotic effect of 4% pilocarpine-PVA and oily drops on 13 elderly people. The miosis developed fast within 15 min, and maximum miosis was rached within 1 h. Oily drops of pilocarpine induced stronger maximum miosis than corresponding PVA-drops. The pupil remained contracted to less than 50% of its starting diameter after pilocarpine-PVA drops for 3-4 h and after oily drops for 9 h and returned to its starting diameter after pilocarpine-PVA drops 9-10 h and after oily drops 20-24 h following administration. The difference in the effect between pilocarpine-PVA and oily drops was independent of the subjects' age.