Sg. Krohne et al., INHIBITION OF PILOCARPINE-INDUCED AQUEOUS-HUMOR FLARE, HYPOTONY, AND MIOSIS BY TOPICAL ADMINISTRATION OF ANTIINFLAMMATORY AND ANESTHETIC DRUGS TO DOGS, American journal of veterinary research, 59(4), 1998, pp. 482-488
Objective-To investigate the mechanism by which pilocarpine causes inc
reased aqueous humor (AH) flare, hypotony, and miosis in dogs. Animals
-6 dogs with normal eyes. Procedure-Both eyes of each dog were treated
topically with a 2% solution of pilocarpine, and 1 eye of each dog wa
s additionally treated with commercially available ophthamic solutions
. Breakdown of the blood-aqueous barrier (BAB) was quantitated in each
eye, using laser flaremetry to measure AH flare. Intraocular pressure
and pupil size were also measured. Results-Pilocarpine caused increas
ed flare from BAB breakdown that was inhibited by the drugs tested. In
hibition (most to least) of BAB breakdown was flurbiprofen more than d
iclofenac, proparacaine, or suprofen, which were more than 0.125 or 1.
0% prednisolone. Inhibition appeared dose-dependent and caused consens
ual inhibition in the contralateral eye. Intraocular pressure was decr
eased only in proparacaine-treated eyes and increased in eyes treated
with nonsteroidal anti-inflammatory drugs (NSAID). Flurbiprofen and pr
oparacaine were the most effective at blocking miosis. Conclusions-Pil
ocarpine produced a predictable, reproducible BAB breakdown in dogs. M
iosis and increased AH flare were inhibited equally by proparacaine or
NSAID, suggesting that these signs were caused by neuropeptide releas
e into the AH from antidromic stimulation, which subsequently triggers
prostaglandin production. Hypotony was inhibited only by anti-inflamm
atory drugs. Clinical Relevance-Proparacaine in combination with piloc
arpine would be the best choice for treating dogs with acute glaucoma.
Topical administration of NSAID should not be used to treat dogs with
acute glaucoma, because they increase intraocular pressure and negate
the effects of pilocarpine.