09/10/2021
A cataract describes any opacity of the normally transparent and avascular lens. Cataractogenesis occurs most commonly as a result of hereditary factors; however, it may also result from systemic disease (notably diabetes mellitus), lenticular trauma/inflammation, dietary deficiencies (notably associated with the use of milk replacers), exposure to pharmacologic agents (notably ketoconazole), as a sequela to the retinal atrophies (RAs), and following exposure to therapeutic radiation and chronic exposure to sunlight. Changes may be unilateral or bilateral, symmetrical or asymmetrical. A “hypermature” (or “Morgagnian”) cataract describes a cataract in which the lens cortex has begun to liquefy and resorb. The lens nucleus may sink and the capsule shrink, fibrose, and calcify. Hypermature cataracts typically have a crystalline appearance and are frequently associated with symptoms of chronic uveitis. Variable degrees of tapetal reflectivity and/or visual impairment may be present. Many breeds (and mixed breeds) may be affected by hereditary cataracts and many breed-related features including age of onset and rate of progression are described. Commonly affected breeds include the Boston Terrier, Bichon Frisé, Cocker Spaniel, Labrador Retriever, Miniature Schnauzer, Miniature Poodle, and Siberian Husky.
Morgagnian cataract may undergo spontaneous rupture into the anterior chamber causing an inflammatory reaction, which is known as phacoanaphylactic uveitis. Spontaneous rupture of lens capsule may cause secondary glaucoma. It may also be complicated with phacolytic glaucoma when the lens protein leaked through the anterior capsule clogging the trabecular meshwork obstructing the aqueous outflow.
During the presented case we were able to observe high intraocular pressure bilaterally (71mmhg- in right eye and 34mmhg- in left eye), which gives the idea of secondary glaucoma due to hypermature cataract.