Ocular Pathology

Anatomy and pathology of the human eye. Use it to review eye pathology for Ophthalmology Board Review or OKAP.

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Sunday, July 01, 2007

Posterior Subcapsular Cataract

Definition: An opacity in the lens positioned just anterior to the posterior lens capsule and characterized by the posterior migration of lens epithelial cells from the lens bow.
Incidence/Prevalence: Posterior subcapsular cataract may be the most common abnormality involving the lens epithelium.
Etiology: The lens is composed largely of crystallins which aggregate in cataract formation. There are many associations with posterior subcapsular cataracts including chronic vitreal inflammation, ionizing radiation, trauma and prolonged use of corticosteroids.
Clinical Findings: Younger individuals may be affected and the symptoms include complaints of glare at night with bright headlights or poor vision with accommodation. Near vision may often be more affected than distance vision. Usually the earliest sign is a focal dot-like area on the posterior capsule or a reflective sheen. With progression, translucent opacities appear (the swollen Wedl cells) on the posterior capsule that have been likened to a “cloth of gold” or “fish eggs”. Posterior capsular cataract is associated with cortical degeneration and nuclear sclerosis.
Gross: An opacity that is central and irregular is the most frequent finding (arrow 1). Tangential lighting with transillumination will reveal that the opacity lies adjacent to the posterior lens capsule. Because cataracts are usually associated with other lens changes, careful examination will often reveal spokes or other cortical changes (arrow 2).
Histopathology: Normally, the posterior capsule is devoid of epithelium. The presence of nucleated lens epithelial cells (arrow 3) anterior to the posterior capsule (arrow 4) is the key histologic criterion for posterior subcapsular cataract. Posterior subcapsular cataract begins with presumed proliferation and posterior migration of epithelial cells from the lens bow. These cells, also known as bladder or Wedl cells may enlarge five or six fold. However, they do not always appear swollen in sections.
Treatment: Surgical removal of the cataract generally restores vision. In children medicated with steroids, posterior subcapsular cataract may be abated when the steroids are stopped.

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