A cataract is a clouding of the eye's lens, which is normally clear, leading to impaired vision. This cloudiness causes vision to appear blurry, hazy, or foggy, as if looking through a frosted or fogged-up window. Cataracts often develop slowly and primarily affect older adults, but they can also occur due to injury, certain diseases, or be present from birth. Symptoms include blurred vision, difficulty seeing at night, sensitivity to glare, seeing halos around lights, and colors appearing faded or yellowed. Cataracts do not usually cause pain but can lead to significant vision loss if untreated. Surgery to remove the clouded lens and replace it with a clear artificial lens is the most effective treatment.

How Cataracts Affect Vision

The lens of the eye focuses light onto the retina to create a clear image. When cataracts develop, the lens becomes opaque, blocking or scattering light and reducing vision clarity. This results in blurred or dim vision and difficulty seeing fine details, especially in low light or glare conditions.

Causes and Risk Factors

Cataracts mainly result from the natural aging process, where proteins in the lens degenerate and clump together. Other causes include eye trauma, radiation exposure, congenital defects, diabetes, prolonged corticosteroid use, smoking, and excessive sunlight exposure. Oxidative stress and changes in lens metabolism contribute to protein damage and cataract formation.

Types of Cataracts

• Nuclear cataracts: Affect the center of the lens, causing distant objects to blur.
• Cortical cataracts: Begin at the lens edges and spread inward.
• Posterior subcapsular cataracts: Form at the back of the lens and can rapidly affect reading vision.
• Congenital cataracts: Present at birth or develop in early childhood.

Treatment

Cataract surgery is a common, safe, and effective procedure where the cloudy lens is replaced with an artificial intraocular lens (IOL). Surgery is generally recommended when cataracts significantly impair daily activities.

In summary, a cataract is a clouding of the eye lens that gradually reduces vision, commonly due to aging, and is treatable by surgery.