Peer-reviewed veterinary case report
How eye drops affect eye pressure and pupil size in normal cats
By Stadtbäumer, Katrin et al.·Published in Veterinary ophthalmology·2006·Clinic for Surgery and Ophthalmology·View original on PubMed →
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Original publication title: Effects of mydriatics on intraocular pressure and pupil size in the normal feline eye.
- Species:
- cat
Plain-English summary
A group of 10 healthy adult cats was tested to see how different eye drops affected their pupil size and eye pressure. The drops included 1% atropine, 1% cyclopentolate, 0.5% tropicamide, and 10% phenylephrine. The results showed that atropine caused the most significant increase in eye pressure and dilated the pupils the most, while phenylephrine had little to no effect. The changes in pupil size lasted longer than the changes in eye pressure.
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Abstract
OBJECTIVE: To determine the effect of various mydriatics (1% atropine, 1% cyclopentolate, 0.5% tropicamide, 10% phenylephrine) on intraocular pressure (IOP) and pupil size (PS) in normal cats. ANIMALS STUDIED: The mydriatics were tested in 10 adult ophthalmoscopically normal European Domestic Short-haired cats. Procedure Single-dose drug studies were divided into placebo (vehicle of phenylephrine), 10% phenylephrine, 0.5% tropicamide, 1% cyclopentolate and 1% atropine. After measurement of IOP and pupil size (PS) at 8 a.m. on the first day, one drop of the tested drug was applied to one randomly selected eye. The IOP and PS were measured for a minimum of 36 h until the pupil returned to pretest size. RESULTS: Ten per cent phenylephrine had no significant effect on IOP, and the effect on the pupil size was minimal (<or= 1 mm difference). One per cent atropine showed a maximal mean difference of 4.3 mmHg +/- 4.1 mmHg in IOP compared to the untreated eye. These differences were statistically significant at 1, 3, 6, 12 and 16 h post-treatment. At 1, 1.5 and 2 h after unilateral application of 1% cyclopentolate, the IOP in the treated eye was significantly higher than the IOP in the untreated eye with a maximal mean difference of 4.1 mmHg +/- 4.5 mmHg. With 0.5% tropicamide, IOP of the treated eye was significantly higher than IOP of the untreated eye at 1 and 1.5 h after treatment with a maximal mean difference of 3.5 mmHg +/- 3.3 mmHg. One per cent atropine caused the greatest increase in IOP, followed by 1% cyclopentolate and 0.5% tropicamide. The dilating effect of atropine, cyclopentolate and tropicamide lasted longer than the effect on intraocular pressure. CONCLUSIONS: The parasympatholytics 1% atropine, 1% cyclopentolate and 0.5% tropicamide caused a statistically significant elevation of IOP and produced mydriasis in the treated eye in normal cats, while the sympathomimetic 10% phenylephrine had no significant effect on IOP or pupil size.
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Search related cases →Original publication on PubMed: https://pubmed.ncbi.nlm.nih.gov/16771758/