Causes, treatment, and outcome of hyphema, fibrin, and vitreal hemorrhage in horses: 219 cases (2012-2023).

Objective: To determine the causes, time to resolution, effect of therapeutics, and ocular sequelae of hyphema, fibrin, and/or vitreal hemorrhage in horses.
Animals: 225 horses (219 eyes) who were diagnosed with hyphema, fibrin, and/or vitreal hemorrhage.
Methods: Records were retrospectively reviewed for the horses. Signalment, ophthalmic examination findings, causes, treatments, and outcomes were evaluated.
Results: Common causes of intraocular fibrin or hemorrhage were equine recurrent uveitis (42/219 horses), corneal stromal abscess (32/219 horses), corneal stromal ulcer (25/219 horses), and trauma (21/219 horses). Eyes with fibrin that were treated with intracameral tissue plasminogen activator (TPA; n = 18 eyes) had significantly lower days to resolution (8.9 ± 12.6 days) compared to eyes not treated with TPA (28.3 ± 46.7 days). Ocular sequelae in horses with fibrin, such as cataracts (18/120 eyes), synechiae (11/120 eyes), and vision loss (17/120 eyes), were significantly less common in eyes treated with TPA. Sequelae in eyes with hyphema included cataracts (9/36 eyes), synechiae (6/36 eyes), and vision loss (5/36 eyes). Although 41 horses had an enucleation at presentation because of severe disease, 14/144 (< 10%) of horses with follow-up required an enucleation.
Clinical Relevance: The presence of blood products in the eyes of horses suggests severe ocular disease, but if the eye is not enucleated at presentation, the prognosis is good for maintaining the eye. Also, the use of intracameral TPA in horses with anterior chamber fibrin but not those with hyphema, results in less adverse ocular sequelae.