Cataract

– A congenital or degenerative opacity of the lens that leads to a gradual loss of vision.

Causes and Incidence

Cataracts are associated primarily with aging (senile cataracts) and chemical changes in lens proteins. Trauma, toxins, systemic disease, and intraocular inflammation are also causes. Congenital cataracts, which are rare, are the result of inborn errors of metabolism, exposure of a first-trimester fetus to rubella or toxins, and congenital anomalies. Cataracts are the third leading cause of blindness in the United States, and virtually everyone would develop cataracts if they lived long enough. More than 60% of those over 65 years of age and 90% of those over age 85 demonstrate lens opacities.

Disease Process

Senile cataracts form as a result of a chemical change in the gelatinous lens protein encapsulated behind the iris. As a result, the protein coagulates, the lens gradually clouds, and normal lens fibers swell and migrate within the lens. Because of these changes, a blurred image is cast on the retina. If the condition goes untreated, the opacity eventually becomes complete and blindness results.

Symptoms

Symptoms include progressive, painless blurring and distortion of objects, glare from bright lights, and gradual loss of vision. Signs include a gray or white coloring on the pupil and myopia.

Potential Complications

The primary complication is blindness.

Diagnostic Tests

Cataracts are identified by ophthalmoscopic or slitlamp examination.

Treatments

Surgery
Intracapsular or extracapsular removal of the lens; follow-up laser surgery to remove secondary membrane that often forms.

Drugs
Topical antiinfective drugs, mydriaticcycloplegics, and hyperosmotic agents are used preoperatively; corticosteroids and mydriatics are used postoperatively.

General
Corrective lenses, lens implants, and eyeglasses to correct hyperopia.

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