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Vision Tests

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Your doctor will also tell you if you have reduced near vision.

Refraction

The doctor tests your eyes with different lenses until the lens that corrects your vision the best (sometimes better than 20/20 or 6/6) is found. The result of a refraction test determines your prescription eyeglass or contact lens strength.

Visual field test

Normally, a person's visual field forms a rough circle with a natural blind spot. If your vision is normal, you should be able to see objects clearly throughout the entire visual field except for the area with the natural blind spot. When you are using both eyes to see, the blind spots do not interfere with your vision.

You may have vision loss in certain areas of the visual field if you are not able to see:

  • Test objects during tangent screen testing.
  • Movements or light flashes during perimetry testing.

Abnormal results during Amsler grid testing include:

  • Not being able to see the black dot at the center of the grid.
  • Not being able to see all four edges of the grid.
  • Having blank spots or dark spots on the grid (other than the black dot at the center).
  • Seeing lines that look wavy or curved.

Gaps in different parts of the visual field may have many causes, including eye diseases (such as glaucoma and macular degeneration) or nervous system problems (such as stroke). If results on any of the visual field tests are abnormal, you will need further tests to determine the cause.

Color vision test

People who have normal color vision are able to distinguish the colored numbers, symbols, or paths from the background of colored dots.

If you are not able to distinguish some or all of the colored patterns from the background, you may have a color vision problem. You may be able to pick out some patterns of colors but not others. Or you may be able to pick out patterns that are different from a person with normal vision, depending on what type of color vision problem you have.

Many conditions can change your vision test results. Your doctor will discuss any significant abnormal results with you in relation to your symptoms and past health.

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

  • Your ability to understand or follow instructions. Some vision tests cannot be done on babies, small children, or people who cannot understand or follow the instructions.
  • Your ability to stay alert and respond to questions.
  • Failure to wear prescribed eyeglasses or contact lenses.
  • Poor lighting.

WebMD Medical Reference from Healthwise

Last Updated: May 29, 2013
This information is not intended to replace the advice of a doctor. Healthwise disclaims any liability for the decisions you make based on this information.

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