Amsler grid test

Alternative names
Visual acuity test - home; Home vision tests

Definition
Home vision tests measure the ability to see fine detail.

How the test is performed

There are 3 vision tests that can be done at home: distance vision, near vision, and Amsler grid testing.

DISTANCE VISION:
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.

NEAR VISION:
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.

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 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.

How to prepare for the test
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.

Children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child’s age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child’s age:

     
  • Toddler test or procedure preparation (1 to 3 years)  
  • Preschooler test or procedure preparation (3 to 6 years)  
  • Schoolage test or procedure preparation (6 to 12 years)  
  • Adolescent test or procedure preparation (12 to 18 years)

How the test will feel

The test cause no discomfort.

Why the test is performed
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 Values

     
  • Distance vision test: All letters on the 20/20 line read correctly.  
  • Near vision test: The ability to read line labeled 20/20 or J-1.  
  • Amsler grid test: All lines appear straight and unbroken with no distorted or missing areas.

What abnormal results mean
Abnormal results may mean there is a vision problem or eye disease and that you should have a professional eye examination.

Distance vision test: If the 20/20 line is not correctly read, it may be a sign of nearsighte dness (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 ).

Amsler grid test: If the grid appears distorted or broken, there may be a problem with the retina.

What the risks are
The tests have no risks.

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

     
  • Difficulty focusing on near objects  
  • Objects or faces looking blurred or foggy  
  • Double vision  
  • Impression of “skin” or “film” over the eye  
  • Frequent changing of glasses  
  • Trouble seeing at night, trouble adjusting to darkened rooms  
  • Light flashes, dark spots, or ghostlike images  
  • Rainbow-colored rings around lights  
  • Straight lines look wavy  
  • Eye pain  
  • A curtain-like blotting-out of vision

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

     
  • Getting very close to an object (for example, television) in order to see it  
  • Watering eyes  
  • Crossed eyes  
  • Head-tilting  
  • Excessive blinking  
  • Squinting  
  • Difficulty in school

Johns Hopkins patient information

Last revised: December 5, 2012
by David A. Scott, M.D.

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