The effects of 1% prednisolone acetate on pupil diameter and intraocular pressure in healthy dogs treated with 0.005% latanoprost

Purpose: Prostaglandin analogs contribute to blood-aqueous barrier breakdown and may exacerbate uveitis. As these analogs induce de novo synthesis of endogenous prostaglandins, their therapeutic, hypotensive effect could potentially be inhibited by anti-inflammatory treatment. We therefore evaluated whether topical 1% prednisolone acetate alters the effects of 0.005% latanoprost on pupil diameter (PD) and intraocular pressure (IOP). Animals studied: Ten healthy Labrador retriever dogs from the Israel Guide Dog Center for the Blind. Methods: Pupil diameter and IOP were measured hourly, 8 AM–4 PM, with the right and left eyes serving as control (CE) and treated (TE) eyes, respectively. Measurements were conducted during four sessions: (1) without treatment (n = 10), (2) following latanoprost treatment (n = 10) at 8 AM, (3) following prednisolone treatment (n = 7) at 8 AM, and (4) bilateral latanoprost treatment at 8 AM, prednisolone treatment in TE at 11 AM (n = 8). The different number of dogs in sessions 3 and 4 is because some dogs were matched with their new owners earlier than expected. Results: Pupil diameters were not affected by the addition of prednisolone and, at 4 PM, were 3.82 ± 0.47 and 3.97 ± 0.36 mm in TE and CE, respectively (P = 0.175, Wilcoxon). IOPs were not affected by the addition of prednisolone and, at 4 PM, were 9.0 ± 0.8 and 9.3 ± 0.8 mm Hg in TE and CE, respectively (P = 0.339, Wilcoxon). Conclusion: Prednisolone did not alter latanoprost's miotic and hypotensive effects in normal dogs during this study period.