The effect of topical latanoprost on anterior segment anatomic relationships in normal dogs

Objective: Topical latanoprost 0.005% is commonly used in dogs with primary angle closure glaucoma (PACG), and marked miosis has been reported in the literature. To further explore the effect of topical latanoprost on anterior segment anatomy, we performed iridocorneal angle biometrics in normal beagle dogs.

Methods: Thirty-five normal female beagle dogs were assessed using anterior segment optical coherence tomography (AS-OCT). One eye of each dog was scanned with the AS-OCT in the superotemporal quadrant. One drop of latanoprost 0.005% was applied topically, and the OCT scan was repeated 30 min later. Images were imported into ImageJ, and pupil diameter, anterior chamber angle, angle opening distance, angle recess area (ARA), anterior chamber hemifield, and anterior chamber depth were measured.

Results: A single drop of latanoprost resulted in marked miosis, anterior bowing of the peripheral iris, narrowing of the iridocorneal angle, and shallowing of the anterior chamber. The anterior segment parameters demonstrated a significant reduction (P-value ≤ 0.001) from baseline following latanoprost with the exception of the ARA (P = 0.07).

Conclusions: Latanoprost significantly decreases pupil diameter and narrows the iridocorneal angle in normal female beagle dogs. Therefore, the utility of latanoprost as a prophylactic treatment for PACG in fellow eyes may be limited. Studies using quantitative iridocorneal angle measurements in goniodysgenic dogs are warranted to understand the changes in iridocorneal angle morphology that occur in PACG in response to topical application of latanoprost.