Vision impairment | Symptoms & Causes | Diagnosis

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Vision impairment

What is Vision 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.

Good vision is essential for proper physical development and educational progress in growing children. The visual system in the young child is not fully mature. Equal input from both eyes is required for proper development of the visual centers in the brain. If a growing child's eye does not provide a clear focused image to the developing brain, then permanent irreversible loss of vision may result. Early detection provides the best opportunity for effective, inexpensive treatment.


The most common causes of visual impairment globally are:

  • Refractive error (42%)
  • cataract (33%)
  • glaucoma (2%)
  • age related macular degeneration (1%)
  • corneal opacification (1%)
  • diabetic retinopathy (1%)
  • childhood blindness
  • trachoma (1%)
  • < undetermined (18%)

Diagnosis & Tests

It is important that people be examined by someone specializing in low vision care prior to other rehabilitation training to rule out potential medical or surgical correction for the problem and to establish a careful baseline refraction and prescription of both normal and low vision glasses and optical aids. Only a doctor is qualified to evaluate visual functioning of a compromised visual system effectively. The American Medical Association provides an approach to evaluating visual loss as it affects an individual's ability to perform activities of daily living.
Screening adults who have no symptoms is of uncertain benefit.

Prevention & Risk Factors

The World Health Organization estimates that 80% of visual loss is either preventable or curable with treatment. This includes cataracts, onchocerciasis, trachoma, glaucoma, diabetic retinopathy, uncorrected refractive errors, and some cases of childhood blindness.

Treatments & Therapies

Aside from medical help, various sources provide information, rehabilitation, education, and work and social integration.