Medical Encyclopedia


Medical Encyclopedia

Other encyclopedia topics:  A-Ag  Ah-Ap  Aq-Az  B-Bk  Bl-Bz  C-Cg  Ch-Co  Cp-Cz  D-Di  Dj-Dz  E-Ep  Eq-Ez  F  G  H-Hf  Hg-Hz  I-In  Io-Iz  J  K  L-Ln  Lo-Lz  M-Mf  Mg-Mz  N  O  P-Pl  Pm-Pz  Q  R  S-Sh  Si-Sp  Sq-Sz  T-Tn  To-Tz  U  V  W  X  Y  Z  0-9 

Home vision tests

Contents of this page:


Visual acuity test
Visual acuity test

Alternative Names    Return to top

Visual acuity test - home; Amsler grid test

Definition    Return to top

Home vision tests measure the ability to see fine detail.

How the Test is Performed    Return to top

There are three vision tests that can be done at home: Amsler grid, distance vision, and near vision testing.


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 directly in front of you, 14 inches away from your eye, and 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, and meet at all the crossing points with no missing areas. If any lines appear distorted or broken you should note the location of these on the grid.


This is the standard eye chart used by doctors adapted for use at home. 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. Each eye is checked 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 was read correctly. Repeat with the other eye.


This is similar to the distance vision test above, but for use at 14 inches. If you wear glasses for reading, wear them for the test. Hold the near vision test card about 14 inches from the 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 which you were able to read accurately.

How to Prepare for the Test    Return to top

A well-lit area at least 10 feet long is needed for the distance vision test. You will need measuring tape or yardstick, eye charts, tape or tacks to hang the eye charts on the wall, pencil to record results, and -- if possible -- another person to help. 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 wall where the chart is.

How the Test Will Feel    Return to top

The tests cause no discomfort.

Why the Test is Performed    Return to top

Vision may change gradually, and you adjust to the change without being aware of it. Home vision tests are useful in early detection of eye and vision problems. Perform home vision tests every year. Many people at risk for macular degeneration may be told by their ophthalmologist to perform the Amsler grid test more frequently.

Normal Results    Return to top

What Abnormal Results Mean    Return to top

Abnormal results may mean there is a vision problem or eye disease and that 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 the 20/20 line is not correctly read, it may be a sign of nearsightedness (myopia), farsightedness (hyperopia), astigmatism, or other eye abnormality.

Near vision test: Not being able to read the small type may be a sign of aging vision (presbyopia).

Risks    Return to top

The tests have no risks.

Considerations    Return to top

If there are any of the following symptoms, have a professional eye examination:

If children have any of the following symptoms, they should also have a professional eye examination.

Update Date: 1/21/2009

Updated by: Paul B. Griggs, MD, Department of Ophthalmology, Virginia Mason Medical Center, Seattle, WA . Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M. Logo

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 1997-2009, A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.