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Home vision tests
Definition
Home vision tests measure the ability to see fine detail.
Alternative Names
Visual acuity test - home; Amsler grid test
How the Test is Performed
There are three vision tests that can be done at home: Amsler grid, distance vision, and near vision testing.
AMSLER GRID TEST:
This test helps detect macular degeneration, a disease that may cause blurred vision, distortion, or blank spots. If you normally wear glasses for reading, wear them for this test. If you wear bifocals, look through the bottom reading portion.
Do the test with each eye separately, first the right and then the left. Hold the test grid right in front of you, 14 inches away from your eye. Look at the dot in the center of the grid, not at the grid pattern.
While looking at the dot, you will see the rest of the grid in your peripheral vision. All the lines, both vertical and horizontal, should appear straight and unbroken. They should meet at all the crossing points with no missing areas. If any lines appear distorted or broken, note their location on the grid.
DISTANCE VISION:
This is the standard eye chart doctors use, which has been adapted for home use.
The chart is attached to a wall at eye level. Stand 10 feet away from the chart. If you wear glasses or contact lenses for distance vision, wear them for the test.
Check each eye separately, first the right and then the left. Keep both eyes open and cover one eye with the palm of the hand.
Read the chart, beginning with the top line and moving down the lines until it is too difficult read the letters. Record the number of the smallest line that you read correctly. Repeat with the other eye.
NEAR VISION:
This is similar to the distance vision test above, but it is held only 14 inches away. If you wear glasses for reading, wear them for the test.
Hold the near vision test card about 14 inches from your eyes. Do not bring the card any closer. Read the chart using each eye separately as described above. Record the size of the smallest line you were able to accurately read.
How to Prepare for the Test
You need a well-lit area at least 10 feet long for the distance vision test, and the following:
- Measuring tape or a yardstick
- Eye charts
- Tape or tacks to hang the eye charts on the wall
- A pencil to record results
- Another person to help (if possible)
The vision chart needs to be tacked to the wall at eye level. Mark the floor with a piece of tape exactly 10 feet from the chart on the wall.
How the Test Will Feel
The tests cause no discomfort.
Why the Test is Performed
Your vision may change gradually. You can adjust to the change without being aware of it.
Home vision tests can help detect eye and vision problems early. Perform home vision tests every year.
People who are at risk for macular degeneration may be told by their ophthalmologist to perform the Amsler grid test more often. It is best to do this test once a week. Macular degeneration changes are gradual, and you can miss them if you test daily.
Normal Results
- Amsler grid test: All lines appear straight and unbroken with no distorted or missing areas
- Distance vision test: All letters on the 20/20 line read correctly
- Near vision test: You are able to read the line labeled 20/20 or J-1
What Abnormal Results Mean
Abnormal results may mean you have a vision problem or eye disease and you should have a professional eye examination.
- Amsler grid test: If the grid appears distorted or broken, there may be a problem with the retina.
- Distance vision test: If you do not read the 20/20 line correctly, it may be a sign of nearsightedness (myopia), farsightedness (hyperopia), astigmatism, or another eye abnormality.
- Near vision test: Not being able to read the small type may be a sign of aging vision (presbyopia).
Risks
The tests have no risks.
Considerations
If you have any of the following symptoms, get a professional eye examination:
- Difficulty focusing on near objects
- Double vision
- Eye pain
- Feeling like there is a "skin" or "film" over the eye or eyes
- Frequent changing of glasses
- Light flashes, dark spots, or ghost-like images
- Objects or faces looking blurred or foggy
- Rainbow-colored rings around lights
- Straight lines look wavy
- Trouble seeing at night, trouble adjusting to darkened rooms
If children have any of the following symptoms, they should also have a professional eye examination:
- Crossed eyes
- Difficulty in school
- Excessive blinking
- Getting very close to an object (for example, the television) in order to see it
- Head tilting
- Squinting
- Watery eyes
References
Colenbrander A. Measuring vision and vision loss. In: Tasman W, Jaeger EA, eds. Duane's Ophthalmology. 15th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2009:chap 51.
Skarf B, Glaser JS, Trick GL. Neuro-ophthalmologic examination: the visual sensory system. In: Tasman W, Jaeger EA, eds. Duane's Ophthalmology. 15th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2009:chap 2.
American Academy of Ophthalmology Preferred Practice Patterns Committee. Preferred Practice Pattern Guidelines. Comprehensive Adult Medical Eye Evaluation. San Francisco, CA: American Academy of Ophthalmology, 2010. Accessed January 17, 2011.
Miller D, Schor P, Magnante P. Optics of the normal eye. In: Yanoff M, Duker JS, eds. Ophthalmology. 3rd ed. St. Louis, Mo: Mosby Elsevier;2008:chap 2.6.
Reviewed By: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine; and Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision Institute, La Jolla, California. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
