The existence of congenital cataracts has been known for more than 200 years. Documented by Duke-Elder, several subtypes are described; however, a posterior polar cataract is distinct from other forms of congenital lens opacities.
A posterior polar cataract is a round, discoid, opaque mass (see the image below) that is composed of malformed and distorted lens fibers located in the central posterior part of the lens. This location is its most significant feature, in addition to its proximity to and possible adherence with the posterior capsule. Moreover, the capsule itself may be weakened. As such, posterior polar cataract removal is a challenge to the surgeon because of its adherence to or the associated weakness of the posterior capsule.
The posterior polar cataract is seen as a dense discoid opacity. The central fibrous mass consists of degenerated lens fibers surrounded by several small globular vacuoles containing what appears as a refractile substance as well as some lens degenerative fiber material.
See What the Eyes Tell You: 16 Abnormalities of the Lens, a Critical Images slideshow, to help recognize lens abnormalities that are clues to various conditions and diseases.
Posterior polar cataract, a distinctive subtype of lens opacity, presents as an area of degenerative and malformed lens fibers that form an opacity in the central posterior subcapsular area of the lens. Often, this opacity is adherent to the lens capsule, thereby making uncomplicated surgical removal problematic.
Posterior polar cataract surgery is associated with an increased incidence of rupture of the posterior capsule. Only in recent times have the advances in control of fluidics and aspiration during phacoemulsification prompted various approaches to meet this surgical challenge.