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You are here : 3-RX.com > Medical Encyclopedia > Diseases and Conditions > Visual Impairment

Visual Impairment

Alternate Names : Impaired Vision

Overview, Causes, & Risk Factors | Symptoms & Signs | Diagnosis & Tests | Prevention & Expectations | Treatment & Monitoring

Visual impairment refers to sight that has less quality, strength, or value than normal. Sight becomes weakened or damaged in some way.

What is going on in the body?

Some people are born with visual impairments. Vision changes can also occur in people of any age for a number of reasons, including conditions within the eyes, as well as conditions within the brain. The change in a person's sight may be minor or severe. Vision problems can range from an inability to see certain colors to blurred vision or complete loss of sight. The visual impairment may be acute, meaning occuring suddenly, or chronic, which means that the visual changes last for a long period of time.

What are the causes and risks of the condition?

A person may be born with visual impairments, or they may occur later in life. Common causes of visual impairment include the following:

  • damage to the visual nerves, such as that caused by head injury,brain tumor, or infection
  • diabetes
  • glaucoma, or abnormally high pressure inside the eye
  • injuries to the eye, such as corneal injuries
  • brain damage, such as that from a stroke, or brain attack
  • refractive errors, which means that objects appear blurry only when they are up close or when they are far away. This is commonly known as being nearsighted or farsighted. Nearsightedness, or myopia, means that objects that are far away are not seen clearly. Farsightedness, or hyperopia, means that objects that are close are blurry, while objects far away can be seen clearly. These conditions often are the reasons people need glasses.
  • color blindness, an inherited condition that is much more likely in males
  • macular degeneration, a common cause of poor sight in the elderly. This condition affects the retina, or back of the eye, and occurs for unknown reasons.
  • cataracts, another common cause of poor vision in the elderly, although it can occur even in newborn babies Cataracts describe a clouding of the lens, or focusing, part of the eye.
  • aging, which can cause people to need reading glasses or bifocals starting around the age of 40 or 50. This condition is called presbyopia and is considered normal.
  • astigmatism, or blurred vision in only certain areas of sight, which is caused by abnormal bending of light through the eye
  • medication side effects, such as those from the heart medication digoxin or the antibiotic ethambutol


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    Visual Impairment: Symptoms & Signs

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