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eye examination Alternative Names
routine eye examination, standard ophthalmic examination
Definition
In a routine eye examination, a person's eyes are examined with special instruments that can detect normal and abnormal structures and conditions. The person's visual acuity, peripheral vision and colour vision, are measured, as well.
Who is a candidate for the test?
Everyone should have regular eye examinations. If a person does not have eye problems, it is recommended they have their eyes examined every 3 to 5 years until about the age of 50. After 50 years old, the eyes may need to be checked more frequently for eye disorders. If a person has other eye problems, the doctor may recommend eye examinations more frequently. Children should have their first eye examination at around the age of 3 or 4 years old.
How is the test performed?
First, the doctor will ask about the eyes, any vision problems and general health. Next, he or she will test the eye muscles to see if eye movements are normal. Peripheral vision, or the ability to see out of the side of the eyes, can be tested as well.
Before the eyeballs are examined, the person is asked to read a standard eye chart to determine how well the person can see, or to check the visual acuity. The person is usually assigned a numeric value for each eye, such as 20/20 or 6/6 vision or excellent vision, or 20/40 or 6/12 for poorer vision. The larger the bottom number of the fraction is, the worse the vision. Then, the person is given a series of coloured dot patterns to test the ability to see colours.
Often, the doctor will put special eye drops into the eyes that cause the pupils to open wider, or dilate. When the pupils are wide open, the doctor can get a better view of the inside of the eyes.
Once the pupils are dilated, the doctor will look into each eye with a special instrument called an ophthalmoscope. Through this instrument, the internal structures of the eye can be seen. These structures include the retina, the back of the eyeball or the fundus, the blood vessels and the head of the optic nerve, which carries the images a person sees to the brain. The surface of the cornea, the outermost portion of the front of the eye, can be examined for defects or scratches. The pressure inside the eyeball can be measured to test for glaucoma. Glaucoma is a disease of the eye in which there is increased pressure inside the eyeball. It can cause a gradual loss of vision.
What is involved in preparation for the test?
A person should request specific instructions from the doctor. Usually, no preparation is necessary for a routine eye examination.
What do the test results mean?
Normal results include the following: - 20/20 or 6/6 vision
- the ability to see colours
- normal optic nerve, retina, blood vessels, and fundus
- no evidence of glaucoma
- a transparent cornea free of scratches
Abnormal results may include the following: - myopia, or nearsightedness, which is the ability to see near objects better than far objects
- astigmatism, or blurred vision
- hyperopia, or farsightedness, which is the ability to see far objects better than near objects
- presbyopia, or an inability to focus on near objects that often occurs in middle-aged persons
- colour blindness, which is an inability to see certain colours
- blocked tear duct, or a blockage in the tube that carries tears away from the eye
- cataracts, or a clouding of the lens in the eye that can cause vision problems
- eye trauma or injury
- lazy eye, an eye movement disorder also called strabismus
- eye diseases
- glaucoma
- damage to the optic nerve, blood vessels, or fundus
- scratches or defects on the cornea
Author: David T. Moran, MD
Reviewer: eknowhow Medical Review Panel
Editor: Dr John Hearne
Last Updated: 6/06/2005
Contributors
Potential conflict of interest information for reviewers available on request |
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