Effect of Topical 1% Tetracaine Hydrochloride on Intraocular Pressure in Ophthalmologically Normal Horses; a Pilot Study.

The research study investigates the impact of topical 1% tetracaine hydrochloride on the intraocular pressure (IOP) of healthy horses. It concluded with no significant changes in IOP after applying 1% tetracaine.

Study Methodology

• The study included 30 eyes of 15 clinically normal horses.
• The horses were evenly split into two groups: a treatment group and a control group.
• Before applying 1% tetracaine or placebo, the initial IOP readings (T0) were documented for every horse in both groups.
• One drop of tetracaine was applied to one eye of each horse in the treatment group (comprising 8 horses).
• In the control group (7 horses), one drop of artificial tear was applied to one randomly selected eye.

Outcome Measurements

• The IOP was measured repeatedly at 2 minutes (T2), 5 minutes (T5), 15 minutes (T15), and 30 minutes (T30) after application with a rebound tonometer.
• The comparisons were made between IOP readings at different time intervals.

Study Results

• No significant variation was observed in the treatment group’s IOP readings (P = .3).
• The highest IOP value noted at T2 returned back to the baseline value at T30.
• There was no substantial discrepancy found in the mean IOP values between the treatment and the control groups.
• Similarly, no significant differences were observed between the males and females at any of the timepoints (P > .05).

Conclusion

• The results of the study demonstrated a nonsignificant increase in the IOP 2 minutes post the instillation of 1% tetracaine in horses.
• This suggests that applying topical 1% tetracaine may not influence IOP in a significant way in clinically normal horses.