Equine phacoclastic uveitis: the clinical manifestations, light microscopic findings, and therapy of 7 cases.

This study is about diagnosing and treating lens rupture in horses – both acutely and chronically – a condition which causes inflammation and often leads to blindness if not attended to quickly and thoroughly.

Clinical Manifestations

• The acute symptoms of a lens rupture include a developing cataract, pigmentation of the iris being displaced into the lens, parts of the lens cortex sticking to the iris and corneal endothelial cells, miosis (excessive constriction of the pupil), and enough inflammation of the eye’s fluids to cause a noticeable cloudiness. It was also found that there usually was a corneal or scleral perforation associated with the rupture that led to ulceration or corneal edema and scarring.
• The signs of chronic phacoclastic uveitis – the long-term inflammation caused by the lens rupture – are blindness, shrunken and non-functional eyeballs (phthisis bulbi), and a general opacity of the cornea due to scarring, new blood vessels forming, pigmentation, and edema (swelling caused by excess fluid).

Treatment

• In one case, a horse with acute phacoclastic uveitis was successfully treated by removing the ruptured lens using phacoemulsification – a procedure involving the use of ultrasonic waves to break the lens into small pieces, which are then suctioned out. The inflammation was controlled with medicinal therapy.
• For horses with chronic phacoclastic uveitis, however, the treatment was more drastic. The inflamed eyes had to be removed – a process called enucleation – despite attempts to manage the inflammation and non-ulcerative keratitis (inflammation of the cornea) with long-term medication.

Comparison with Other Animals

• The symptoms and the lack of effect of medicinal therapy are similar to what has been found in dogs, cats, and rabbits, but the microscopic findings in horses are different from those in dogs and rabbits.