Health Encyclopedia

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 3 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. This is a disease that causes blurred vision, distorted vision, or blank spots in the vision. 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 (35 centimeters) 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 using a pen or pencil.

DISTANCE VISION

This is the standard eye chart that doctors use, it has been adapted for home use.

The chart is attached to a wall at eye level. Stand 10 feet (3 meters) 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 to read the letters. Record the number of the smallest line that you know you read correctly. Repeat with the other eye.

NEAR VISION

This is similar to the distance vision test above, but the near vision test card is held only 14 inches (35 centimeters) away. If you wear glasses for reading, wear them for the test.

Hold the card about 14 inches (35 centimeters) 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.

Recently, smartphone apps have become available that can measure your vision and even produce a prescription. Most of these apps require an additional device to attach to your phone. Be sure to verify their accuracy before relying on them.

How to Prepare for the Test

You need a well-lit area at least 10 feet (3 meters) 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), since they can stand close to the chart and tell you if you read the letters correctly

The vision chart needs to be tacked to the wall at eye level. Mark the floor with a piece of tape exactly 10 feet (3 meters) 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 without you being aware of it.

Home vision tests can help detect eye and vision problems early. Home vision tests should be performed under the direction of your health care provider to detect changes that may occur between eye exams. They do not take the place of a professional eye exam.

People who are at risk of developing macular degeneration may be told by their ophthalmologist to perform the Amsler grid test more often. It is best to do this test not more often than once a week. Macular degeneration changes are gradual, and you can miss them if you test daily.

Normal Results

Normal results for each of the tests are as follows:

• 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
• 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) to see it
• Head tilting
• Squinting
• Watery eyes

References

Chuck RS, Dunn SP, Flaxel CJ; American Academy of Ophthalmology Preferred Practice Pattern Committee, et al. Comprehensive adult medical eye evaluation preferred practice pattern. Ophthalmology. 2021;128(1):1-29. www.aaojournal.org/article/S0161-6420(20)31026-5/fulltext. Published November 12, 2020. Accessed April 5, 2023.

Prokopich CL, Hrynchak P, Flanagan JG, Hynes AF, Chisholm C. Ocular health assessment. In: Elliott DB, ed. Clinical Procedures in Primary Eye Care. 5th ed. Philadelphia, PA: Elsevier; 2021:chap 7.

Review Date:2/12/2023
Reviewed By:Franklin W. Lusby, MD, Ophthalmologist, Lusby Vision Institute, La Jolla, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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