The effects of intravenous romifidine on intraocular pressure in clinically normal horses and horses with incidental ophthalmic findings.

Design: Original study.

Objective: To evaluate the effect of sedation with romifidine hydrochloride 1% (Sedivet: Boehringer-Ingelheim) on intraocular pressure (IOP) in the normal horse and horses with incidental ophthalmic findings as measured by applanation tonometry.

Animals: Nineteen clinically normal horses (13 geldings, six mares) and eight horses (three geldings, five mares) with incidental ophthalmic findings were included in this study.

Procedures: All horses underwent complete ophthalmic examination with pharmacologic mydriasis a minimum of 2 weeks prior to IOP evaluation. Baseline intraocular pressure values were obtained following auriculopalpebral nerve block and topical anesthetic. Immediately thereafter, romifidine was administered intravenously (75 µg/kg) and the IOP recorded at 5, 15, 30, 45 and 60 min postsedation in both eyes. Five successive readings were obtained at each time point, the low and high value discarded, and three remaining readings averaged for a mean.

Results: The changes with time were consistent between eyes and OD and OS results were pooled. The mean IOP at baseline was 26.35 ± 5.57 mmHg. Mean IOP values were significantly lower than baseline at 5 (P < 0.0001), 15 (P < 0.0001), 30 (P = 0.0003), 45 (P < 0.0001) and 60 (P = 0.0005) minutes. The largest change from baseline (16.7%) was noted at t = 15 min.

Conclusions And Clinical Relevance: Administration of romifidine significantly decreased the IOP from baseline at all time points measured. The greatest decline in IOP was noted at 15 min postsedation. Results are consistent with other studies noting a decline in IOP with administration of α-2 agonists.