Purpose: To describe the clinical and histopathologic features of glaucoma associated with Descemet's membrane (DM) detachment in five horses without prior history of intraocular surgery.
Animals studied: Three Appaloosa horses and two Thoroughbreds were included in this study. The affected horses ranged in age from 16 to 27 years and presented with severe diffuse corneal edema.
Procedure: Five eyes were enucleated due to intraocular hypertension and/or chronic corneal ulceration. The enucleated globes were evaluated by the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW). Each globe was routinely processed for histopathology and analyzed by light microscopy. A histologic diagnosis of glaucoma was reached by demonstrating a loss of optic nerve axonal tissue by measuring neurofilament-immunopositive axons with automated image analysis software.
Results: All five horses presented with unilateral severe diffuse corneal edema that had developed between 2 and 16 weeks prior to enucleation. Intraocular pressures for the affected eyes were between 9 and 87 mmHg prior to enucleation. Descemet's membrane detachment was identified histopathologically in all five globes (5/5, 100%). All five eyes had an avascular spindle cell proliferation filling the space between the displaced peripheral DM and the corneal stroma. Neurofilament immunostaining revealed axonal loss consistent with glaucoma.
Conclusion: Equine glaucoma may be associated with Descemet's membrane detachment. This detachment and glaucoma is a possible differential diagnosis for severe equine corneal edema. In this case series, an eye with a DM detachment had a poor prognosis for retention.
Keywords: Descemet's membrane detachment; corneal edema; equine; glaucoma; ocular hypertension; ophthalmology.
© 2016 American College of Veterinary Ophthalmologists.