A<unk>  is a cloudy area in the lens of the eye that leads to a decrease in vision.<unk> s often develop slowly and can affect one or both eyes. Symptoms may include faded colors, blurry or double vision, halos around light, trouble with bright lights, and trouble seeing at night. This may result in trouble driving, reading, or recognizing faces. Poor vision caused by<unk> s may also result in an increased risk of falling and depression.<unk> s cause half of all cases of blindness and 33% of visual impairment worldwide.<unk> s are most commonly due to aging but may also occur due to trauma or radiation exposure, be present from birth, or occur following eye surgery for other problems. Risk factors include diabetes, longstanding use of corticosteroid medication, smoking tobacco, prolonged exposure to sunlight, and alcohol. The underlying mechanism involves accumulation of clumps of protein or yellow-brown pigment in the lens that reduces transmission of light to the retina at the back of the eye. Diagnosis is by an eye examination. Prevention includes wearing sunglasses and a wide brimmed hat, eating leafy vegetables and fruits, and avoiding smoking. Early on the symptoms may be improved with glasses. If this does not help, surgery to remove the cloudy lens and replace it with an artificial lens is the only effective treatment.<unk>  surgery is not readily available in many countries, and surgery is needed only if the<unk> s are causing problems and generally results in an improved quality of life. About 20 million people worldwide are blind due to<unk> s. It is the cause of approximately 5% of blindness in the United States and nearly 60% of blindness in parts of Africa and South America. Blindness from<unk> s occurs in about 10 to 40 per 100,000 children in the developing world, and 1 to 4 per 100,000 children in the developed world.<unk> s become more common with age. In the United States,<unk> s occur in 68% of those over the age of 80 years. Additionally they are more common in women, and less common in Hispanic and Black people.
Cataract
Ocular hypertension
Glaucoma
Refractive error
Vitreoretinopathy
Oculomotor nerve palsy
Auditory neuropathy
Aberrations of the eye