About Visual Impairment

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Visual impairment

From Wikipedia, the free encyclopedia

Visual impairment, also known as vision impairment or vision loss, is a decreased ability to see to a degree that causes problems not fixable by usual means, such as glasses.[1][2]Some also include those who have a decreased ability to see because they do not have access to glasses or contact lenses.[1] Visual impairment is often defined as a best corrected visual acuity of worse than either 20/40 or 20/60.[3] The term blindness is used for complete or nearly complete vision loss.[3] Visual impairment may cause people difficulties with normal daily activities such as driving, reading, socializing, and walking.[2]

The most common causes of visual impairment globally are uncorrected refractive errors (43%), cataracts (33%), and glaucoma (2%).[4] Refractive errors include near sighted, far sighted,presbyopia, and astigmatism.[4] Cataracts are the most common cause of blindness.[4] Other disorders that may cause visual problems include age related macular degeneration, diabetic retinopathy, corneal clouding, childhood blindness, and a number of infections.[5] Visual impairment can also be caused by problems in the brain due to stroke, prematurity, or trauma among others.[6] These cases are known as cortical visual impairment.[6] Screening for vision problems in children may improve future vision and educational achievement.[7] Screening adults may also be beneficial.[2] Diagnosis is by an eye exam.[2]

The World Health Organization estimates that 80% of visual impairment is either preventable or curable with treatment.[4] This includes cataracts, the infections river blindness andtrachoma, glaucoma, diabetic retinopathy, uncorrected refractive errors, and some cases of childhood blindness.[8] Many people with significant visual impairment benefit from vision rehabilitation, changes in their environmental, and assistive devices.[2]

As of 2012 there were 285 million people who were visually impaired of which 246 million had low vision and 39 million were blind.[4] The majority of people with poor vision are in thedeveloping world and are over the age of 50 years.[4] Rates of visual impairment have decreased since the 1990s.[4] Visual impairments have considerable economic costs both directly due to the cost of treatment and indirectly due to decreased ability to work.[9]

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