Glaucoma
Basic Information
Epidemiology
Genetics and Breed Predisposition
Horses prone to developing recurrent uveitis are at risk for developing glaucoma.
Clinical Presentation
History, Chief Complaint
• The most common cause of glaucoma in horses is chronic or recurrent uveitis (a type of secondary glaucoma). Historically, these horses have multiple episodes of intraocular inflammation followed by a severe, unrelenting bout of ocular cloudiness and discomfort (as a result of the development of glaucoma) that does not respond to traditional uveitis therapy.
• Horses with primary glaucoma most commonly present with partial or diffuse corneal edema. These eyes may or may not be painful.
Physical Exam Findings
• Horses with secondary glaucoma associated with chronic uveitis have high IOP (40–80 mm Hg); diffusely edematous corneas; and signs of chronic intraocular inflammation, such as posterior synechia (adhesions), a miotic pupil, and cataract formation. These eyes may appear enlarged or normal sized (Figure 1).
• Horses with primary glaucoma most commonly present with partial or diffuse corneal edema. These eyes may or may not be painful. Early in the disease process, vision and pupil size may be normal. IOP may range from 35 to 80 mm Hg.
• With chronic primary glaucoma, vision decreases, the cornea becomes diffusely edematous, and other signs of chronic glaucoma may become evident (eg, diffuse corneal edema, corneal striae, retinal and optic nerve degeneration). In general, however, the horse tends to lose vision much later in the disease process compared with dogs and humans. An increased size of the eye (>40–45 mm anterior to posterior) and lens subluxation may also occur late in the disease.