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
- 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
- To check for vision loss in any area of your
- To screen for eye diseases, such as
macular degeneration and
glaucoma, which cause gaps in the visual
- 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
- As part of a routine eye
- To screen for or diagnose color
- 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?).