Effects of Omidenepag Isopropyl Versus Latanoprost Eye Drops on Intraocular Pressure, Pupil Diameter, and Anterior Chamber Parameters in Normal Feline Eyes: A Pilot Study.

Abstract

OBJECTIVES: This study aimed to compare the effect of the newly developed selective prostaglandin E2 receptor agonist, omidenepag isopropyl (OMDI), and latanoprost on intraocular pressure (IOP), pupil diameter (PD), and anterior chamber parameters in normal feline eyes. ANIMAL STUDIED: Twenty-two client-owned cats (n = 44 normal eyes) were included in the study. PROCEDURE: IOP and PD were evaluated at baseline (0), 2, and 4 h after drug administration. Ultrasound biomicroscopy was employed to assess parameters such as the iridocorneal angle (ICA), area of the ciliary cleft (CCA), width of the ciliary cleft, mid-width of the ciliary cleft (mid-CCW), angle-opening distance, length of the ciliary cleft, ciliary muscle thickness (CMT), and scleral ciliary process angle. RESULTS: The OMDI-treated eyes showed a significant reduction in IOP compared with normal control eyes, unlike latanoprost-treated eyes. Compared with the control eyes, latanoprost-treated eyes showed a significantly greater decrease in PD than OMDI-treated eyes. The OMDI-treated eyes demonstrated a statistically significant increase in mid-CCW and CCA compared with the latanoprost-treated eyes. Both the OMDI- and latanoprost-treated eyes showed an increase in ICA and CMT compared with the control eyes. CONCLUSION: OMDI effectively reduced IOP in cats for at least 4 h without reducing PD. An increase in the CCA and mid-CCW, observed exclusively with OMDI, suggests that the hypotensive effect may be mediated by the conventional outflow pathway. Additionally, an increase in CMT in both the OMDI- and latanoprost-treated eyes may indicate an effect on the uveoscleral outflow pathway.