EFFECT OF TOPICAL PILOCARPINE TREATMENT ON TEAR PRODUCTION IN DOGS

Tear production, evaluated every 2 hours from 8 AM to 8 PM by use of t he Schirmer tear test over a 3-day period, was not significantly diffe rent between left and right eyes in 12 dogs. However, a significant di urnal pattern was evident. Tear production was lowest at midday and hi ghest in the late afternoon/early evening. After pilocarpine HCl ophth almic solution (0.25, 1.0, or 2.0%; 1 drop) was administered topically to the left eye of each dog at 7 AM on days 4, 6, and 8, respectively , tear production war determined for both eyes every 2 hours from 8 AM to 8 PM on the day of treatment. Analysis of tear values between eyes and between each eye's treatment and pretreatment values did not reve al significant change for the treated eye, but tear production was sig nificantly less in the untreated eye, compared with its pretreatment v alues and with values in the treated eye. On day 10 (48 hours after th e last treatment), tear production values were not significantly diffe rent between left and right eyes, and for both eyes, were not signific antly different from the mean pretreatment tear production values. Top ical application of 0.25, 1.0, or 2.0% pilocarpine HCl consistently ca used blepharospasm, conjunctival hyperemia, and miosis of the treated eye, without significant increase in tear production. We concluded tha t topical application of pilocarpine, at the concentrations used, may have little value in treating disorders involving reduced tear product ion.