Normal variation in, and effect of 2% pilocarpine on, intraocular pressure and pupil size in female horses.

This research paper investigates the variation in intraocular pressure (IOP) and pupil size in normal female horses, as well as the effect of 2% pilocarpine hydrochloride on these parameters. It was found that the variation in IOP and pupil size was not significant during a set time frame and that a single dose of 2% pilocarpine did not significantly change these parameters. However, after multiple daily applications of 2% pilocarpine, a trend towards increased IOP was observed while the decrease in the vertical size of the pupil was significant.

Study Methodology

• The study involved 10 female horses with normotensive eyes (regular eye pressure).
• Intraocular Pressure (IOP) and horizontal and vertical pupil sizes were measured in these horses from 8 AM to 8 PM at specific time intervals (0, 0.5, 1, 2, 4, 6, 8, 10, and 12 hours).
• This set of measurements was then repeated after introducing a single dose application of 2% pilocarpine hydrochloride into both eyes.
• A second experiment involved the application of 2% pilocarpine twice daily for five days. Measurements of IOP and pupil size were taken at 8 AM and noon during this phase of the study.

Findings of the Study

• The natural variation in IOP and pupil size between 8 AM and 8 PM was found to be insignificant.
• This regularity was not significantly affected after the application of a single dose of 2% pilocarpine.
• In the multiple-dose experiment, the IOP at noon on the fifth day was significantly higher than the IOP in the morning on the first and second days.
• The IOP in the morning on the fifth day was significantly higher than the IOP in the morning and at noon on the first and second days.
• The IOP at noon on the fourth day was also significantly higher than the morning IOP on the first and second days and at noon on the first day.
• The decrease in the vertical size of the pupil after multiple applications of 2% pilocarpine was significant.

Conclusion

• The natural variation in IOP and pupil size in horses between 8 AM and 8 PM is not significant.
• A single dose of 2% pilocarpine does not significantly change these parameters during the same time frame.
• However, after multiple twice-daily applications of 2% pilocarpine, an increasing trend was seen in IOP and a significant decrease was noted in the vertical size of the pupil.