Cataract Confusion Clarified

Anatomy The canine lens is suspended in the eye by zonular ligaments which arise from the ciliary epithelium and attach to the lens at the equator. The lens capsule is an elastic basement membrane which encloses the underlying anterior epithelium and lens fibers. The size of the lens is approximately 7mm in the anterior/posterior aspect and 10mm as the equatorial diameter. The anterior lens capsule is much thicker (50-70um) than the posterior capsule (2-4 um) and is an important factor when performing cataract extraction. Lens fibers run parallel to each other, running from anterior to posterior. However, the fibers don’t quite reach the anterior and posterior poles or cover the entire circumference and thereby form the upright, anterior ‘Y’ suture and inverted, posterior ‘Y’ suture. The lens is nourished in the embryo by the hyaloid artery arising from the posterior segment and later in life, by the aqueous humor and vitreous. Mittendorf’s dot represents the insertion of the hyaloid artery on to the posterior lens capsule.