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Vision Tests

Why It Is Done

Visual acuity tests may be done:

  • As part of a routine eye exam to screen for vision problems. How often you should have routine eye exams changes as you age. Adults and children and teens have different schedules for eye exams.
  • To monitor an eye problem, such as diabetic retinopathy, or to find out if a treatment is working.
  • To determine if you need glasses or contact lenses to improve your vision.
  • After an injury to the eye, to check if your sight was affected.
  • When you obtain or renew your driver's license or for some types of employment.
  • To check the near vision of school-age children who have trouble reading, poor school performance, or blurred vision while doing work up close.

Refraction is done:

  • To determine the correct prescription for eyeglasses or contact lenses.
  • To find out if blurred vision is caused by refractive error or eye disease.

Visual field tests may be done:

  • To check for vision loss in any area of your visual field.
  • To screen for eye diseases, such as macular degeneration and glaucoma, which cause gaps in the visual field.
  • To look for damage to the nerves of the eye following a stroke, head injury, or other condition that causes reduced blood flow to the brain.

Color vision tests may be done:

  • As part of a routine eye exam.
  • To screen for or diagnose color blindness.
  • To screen applicants for jobs in which color perception is important, such as truck driving, electronics, or the military.

How To Prepare

If you wear glasses or contact lenses, bring them with you to the exam since the tests cannot be properly performed without them. If you have a copy of your current eyeglass prescription, bring it with you.

If you have a young child, it is best to practice eye tests at home before you take your child to the appointment. This can help your child cooperate better during the real testing. For more information, see the topic Pediatric Preparation for Medical Tests.

Many medicines may affect the results of vision tests. Be sure to tell your doctor about all the over-the-counter and prescription medicines you take.

Talk to your doctor about any concerns you have regarding the need for vision tests, how they will be done, or what the results will mean. To help you understand the importance of these tests, fill out the medical test information form(What is a PDF document?).

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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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