Effect of topical 1% atropine sulfate on intraocular pressure in normal horses.

The research aims to study the impact of the topical application of 1% atropine sulfate on the intraocular pressure (IOP) in healthy horses. It was found that such treatment resulted in a small, yet significant decrease in IOP in most horses, although some showed an increase, thereby recommending caution in its use for glaucoma treatment.

Study Design and Procedures

• The study included eleven healthy horses subjected to bilateral measurements of their intraocular pressure (IOP) twice a day, at specific time points, over a span of five days.
• The first couple of days did not include any form of medication application. Subsequently, the researchers applied 0.1mL of 1% atropine sulfate ointment topically to one eye of each horse twice a day for three days, rendering this eye as the treatment eye and the other as the control.
• An additional recording of IOP was taken from eight horses three days after stopping the atropine treatment.

Key Findings and Results

• There was no notable difference in the IOP of the treatment and control eyes during the initial two-day period without any medication. However, during the treatment phase, the IOP of the eyes treated with the atropine sulfate ointment was significantly lower in ten out of the eleven horses, showing an average reduction of 11.2%, compared to the untreated eyes.
• Interestingly, one horse experienced a significant increase in IOP in its treated eye compared to the rest of the horses that were part of the study. The researchers did not note any significant variation in the IOP of the control eyes over the observation period.
• There wasn’t any significant variation in the intraocular pressure results recorded at 8AM and 4PM. This indicates that the time of day does not considerably influence this measured pressure.

Conclusions and Clinical Implications

• The research concludes that the use of topical 1% atropine sulfate results in a noticeable, though small reduction in intraocular pressure in most horses with normal ocular pressure. Nevertheless, since it increased the IOP in a horse, researchers recommend caution in its use particularly in horses with glaucoma.
• This research adds to the understanding and treatment of ocular conditions in horses, particularly glaucoma, and highlights the importance of individual responses to medication.