User:Mr. Ibrahem/Visual impairment
Medical condition / 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.[7] The term blindness is used for complete or nearly complete vision loss.[7] Visual impairment may cause difficulties with normal daily activities such as driving, reading, socializing, and walking.[2]
Visual impairment | |
---|---|
Other names | Vision impairment, vision loss |
A white cane, the international symbol of blindness | |
Specialty | Ophthalmology |
Symptoms | Decreased ability to see[1][2] |
Complications | Non-24-hour sleep–wake disorder, falls in older adults[3][4] |
Causes | Uncorrected refractive errors, cataracts, glaucoma[5] |
Diagnostic method | Eye examination[2] |
Treatment | Vision rehabilitation, changes in the environment, assistive devices (eyeglasses, white cane)[2] |
Frequency | 940 million / 13% (2015)[6] |
The most common causes of visual impairment globally are uncorrected refractive errors (43%), cataracts (33%), and glaucoma (2%).[5] Refractive errors include near-sightedness, far-sightedness, presbyopia, and astigmatism.[5] Cataracts are the most common cause of blindness.[5] Other disorders that may cause visual problems include age-related macular degeneration, diabetic retinopathy, corneal clouding, childhood blindness, and a number of infections.[8] Visual impairment can also be caused by problems in the brain due to stroke, premature birth, or trauma among others.[9] These cases are known as cortical visual impairment.[9] Screening for vision problems in children may improve future vision and educational achievement.[10] Screening adults without symptoms is of uncertain benefit.[11] Diagnosis is by an eye exam.[2]
The World Health Organization (WHO) estimates that 80% of visual impairment is either preventable or curable with treatment.[5] This includes cataracts, the infections river blindness and trachoma, glaucoma, diabetic retinopathy, uncorrected refractive errors, and some cases of childhood blindness.[12] Many people with significant visual impairment benefit from vision rehabilitation, changes in their environment, and assistive devices.[2]
As of 2015 there were 940 million people with some degree of vision loss.[6] 246 million had low vision and 39 million were blind.[5] The majority of people with poor vision are in the developing world and are over the age of 50 years.[5] Rates of visual impairment have decreased since the 1990s.[5] Visual impairments have considerable economic costs both directly due to the cost of treatment and indirectly due to decreased ability to work.[13]