Effects of topical administration of 0.005% latanoprost solution on eyes of clinically normal horses.

The study investigates the effects of 0.005% latanoprost solution, typically used for treating glaucoma, on the intraocular pressure (IOP) of healthy horses. Despite its effectiveness in reducing IOP, latanoprost was found to cause a high frequency of side effects, potentially increasing the risk of inflammation in horses prone to uveitis.

Objective and Methodology

This research study aimed to discern the impact of 0.005% latanoprost solution on the IOP of the eyes in healthy horses and to identify the rate of side effects that followed the drug’s administration. The researchers worked with 20 adult, clinically healthy horses. Measurement of IOP was obtained at multiple time intervals across nine days – days 1 and 2 served as a baseline, days 3 to 7 for the treatment period, and days 8 to 9 were used for follow-up.

• The latanoprost solution was applied to one eye (chosen at random) of each horse every 24 hours during the treatment period, following the 7 AM IOP recording.
• The observation attributes also included tracking of pupil size and regular examination for symptoms like conjunctival hyperemia, epiphora, blepharospasm, blepharedema, and aqueous flare alongside IOP measurement.

Findings

The study discovered that the treatment led to a considerable decrease in IOP in the eyes of the horses under treatment. The mean values for this reduction were at 1.03 mm Hg (or 5%) among males and at a higher 3.01 mm Hg (or 17%) amongst females.

• Each of the treated horses experienced some level of miosis – contraction of the pupil – typically reaching a peak between 4 to 8 hours post-treatment.
• A range of side effects were also noted. Conjunctival hyperemia, epiphora, blepharospasm, and blepharedema were found in 100, 57, 42, and 12% of treated eyes respectively, occurring between 2 to 24 hours after the drug was administered. Notably, no instances of aqueous flare were observed at any time during the study.

Conclusion

Although 0.005% latanoprost solution effectively reduced IOP with every daily dose, the presence of side effects was considerably high. It’s noteworthy that recurring uveitis seems to be a risk factor for glaucoma in horses, and this introduces the consideration that routine latanoprost treatment might further the risk of prostaglandin-induced inflammatory conditions in susceptible animals.