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Cataracts are the most common cause of blindness worldwide. In the United States, cataracts lead to visual impairment more frequently than any other cause [link widoczny dla zalogowanych], but—since most of them are treatable—cataracts do not typically lead to permanent blindness in this country. (Congdon N, et al., for the Eye Diseases Prevalence Research Group. Causes and prevalence of visual impairment among adults in the United States. Arch Ophthalmol. 2004;122(4):477-85)
What is a Cataract?The lens—the primary focusing apparatus of the eye—is a transparent, elliptical, lamellar structure (similar to a tightly-packed onion) that is enclosed within a thin, clear capsule at the front of the eye.Aging, disease, and environmental factors reduce the circulation, plasticity, and clarity of the lens. Opacities form within the layers of the lens and, over several years, coalesce to form cataracts.Depending on the location of a cataract within the lens, various degrees of visual impairment may result. Cataracts that form beneath the posterior lens capsule [link widoczny dla zalogowanych], for example [link widoczny dla zalogowanych], disproportionately impair vision because the opacity is situated at a point where incoming light rays cross before proceeding to the retina.What are the Signs and Symptoms of a Cataract? Gradual, painless visual blurringDecreased visual acuity (particularly in bright light or when reading)Impaired color perceptionDecreased contrast sensitivityGlare (especially from bright lights, such as oncoming headlights)Temporarily enhanced near vision (as a lens opacifies, it causes increased near-sightedness; far-sighted individuals who need eyeglasses to see close objects may experience a period of “second sight”)Rarely, a cataract will swell and block the drainage of fluid from the anterior chamber of the eye, causing closed-angle glaucoma and painWhat are the Risk Factors for Cataracts?Age (85% are age-related)Gender (women are affected more frequently than men)Corticosteroid useAlcoholSystemic disease (diabetes, autoimmune illness, etc.)Ultraviolet radiation (particularly UV-B)SmokingEye trauma
How is a Cataract Diagnosed?Cataracts can be detected during clinical examination in a doctor’s office. Routine examination with a hand-held ophthalmoscope will reveal most cataracts (even those that don’t cause noticeable visual impairment).Slit-lamp examination—usually performed by an ophthalmologist or optometrist—can provide more details about a cataract’s size and location within the lens.How are Cataracts Treated?As cataracts develop, patients often require new glasses or frequent changes in old prescriptions.Polarized lenses reduce glare caused by cataracts that don’t yet require surgery.Indirect lighting during reading or other close-up work reduces pupillary constriction and maximizes vision.Cataracts that cause significant visual impairment (best corrected vision is <20/40 or vision is insufficient for accomplishing necessary or desired activities) are candidates for surgery.Modern cataract surgery involves the removal of the entire lens and usually the placement of a silicone or plastic lens to replace the optical power lost by removal of the original lens.Recent developments in intraocular lens technology Rezoom or ReSTOR lenses) allow patients to see at all distances, thus reducing dependence on accessory reading glasses.Cataract surgery is typically performed under local anesthesia and IV sedation; patients often remain awake during the procedure, which may last 15 – 20 minutes.Topical h
(From Rosenberg E, Sperazza L. The visually impaired patient. Am Fam Phys. 2008;77(10):1431-36)
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