Vision Impairment


Description: Image result for slogan for 10th anniversary related to chemistryVision Impairment

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

The most common causes of visual impairment globally are uncorrected refractive errors (43%), cataracts (33%), and glaucoma (2%).Refractive errors include near-sightedness, far-sightedness, presbyopia, and astigmatism. Cataracts are the most common cause of blindness.Other disorders that may cause visual problems include age-related macular degeneration, diabetic retinopathy, corneal clouding, childhood blindness, and a number of infections.Visual impairment can also be caused by problems in the brain due to stroke, premature birth, or trauma among others. These cases are known as cortical visual impairment.Screening for vision problems in children may improve future vision and educational achievement.Screening adults without symptoms is of uncertain benefit.Diagnosis is by an eye exam.

The World Health Organization (WHO) estimates that 80% of visual impairment is either preventable or curable with treatment. This includes cataracts, the infections river blindness and trachoma, glaucoma, diabetic retinopathy, uncorrected refractive errors, and some cases of childhood blindness. Many people with significant visual impairment benefit from vision rehabilitation, changes in their environment, and assistive devices. The definition of visual impairment is reduced vision not corrected by glasses or contact lenses.


The most common causes of visual impairment globally in 2010 were:

  • Refractive error (42%)
  • Cataract (33%)
  • Glaucoma (2%)
  • Age-related macular degeneration (1%)
  • Corneal opacification (1%)
  • Diabetic retinopathy (1%)
  • Childhood blindness
  • Trachoma (1%)
  • Undetermined (18%)

The most common causes of blindness worldwide in 2010 were:

  • Cataracts (51%)
  • Glaucoma (8%)
  • Age-related macular degeneration (5%)
  • Corneal opacification (4%)
  • Childhood blindness (4%)
  • Refractive errors (3%)
  • Trachoma (3%)
  • Diabetic retinopathy (1%)
  • Undetermined (21%)

About 90% of people who are visually impaired live in the developing world. Age-related macular degeneration, glaucoma, and diabetic retinopathy are the leading causes of blindness in the developed world.

Among working-age adults who are newly blind in England and Wales the most common causes in 2010 were:

  • Hereditary retinal disorders (20.2%)
  • Diabetic retinopathy (14.4%)
  • Optic atrophy (14.1%)
  • Glaucoma (5.9%)
  • Congenital abnormalities (5.1%)
  • Disorders of the visual cortex (4.1%)
  • Cerebrovascular disease (3.2%)
  • Degeneration of the macula and posterior pole (3.0%)
  • Myopia (2.8%)
  • Corneal disorders (2.6%)
  • Malignant neoplasms of the brain and nervous system (1.5%)
  • Retinal detachment (1.4%)


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Journal of optometry : open access