Equine Glaucoma (Secondary to Uveitis) – NAVLE Study Guide

Overview and Clinical Importance

Glaucoma is a multifactorial neurodegenerative ocular disease characterized by elevated intraocular pressure (IOP) that leads to progressive loss of retinal ganglion cells and optic nerve damage, ultimately resulting in blindness. In horses, glaucoma is most commonly secondary to equine recurrent uveitis (ERU), making it a critical sequela to recognize and manage. The prevalence of equine glaucoma is reported between 0.07% and 0.5%, though it is likely underdiagnosed because clinical signs are often subtle and easily confused with ongoing uveitis.

Understanding the pathophysiology, clinical presentation, and management of glaucoma secondary to uveitis is essential for the NAVLE, as horses with ERU represent a significant proportion of equine ophthalmology cases encountered in general practice.

Anatomy and Physiology of Aqueous Humor Dynamics

Aqueous humor is produced by the ciliary body epithelium through both active secretion (involving carbonic anhydrase and Na+/K+ ATPase) and passive ultrafiltration. This clear fluid provides nutrients to the avascular lens and cornea while removing metabolic waste products.