Characteristics of a Vision Test

Vision tests administered by optometrists can identify present or potential issues with your vision. Understanding what each test is for and what to expect can help you prepare for your eye appointments by lessening any anxiety. If you wear contact lenses or glasses you should bring these to your appointment.

Acuity Test

• You may not be familiar with the name of this test, but this is the one you are most likely acquainted with. In the acuity test, a chart of letters or symbols is used to measure how well your eyes are able to recognize details both near and far. You'll be asked to read the chart using only your right eye, your left eye and both eyes simultaneously.

Refraction Test

• The refraction test is used to determine if you need lenses to correct your vision. This test is usually administered as a result of your acuity test results. It determines if you suffer from nearsightedness or farsightedness - both of which can be the cause of blurred vision. Your eye doctor may dilate your pupils for this test. After the dilation takes place, the doctor will shine a light into each of your eyes. Next, trial lenses will be placed before your eyes. These lenses are adjusted repeatedly until your retinas properly focus on the light. You will be asked to compare the effects of each lens, letting the doctor know which lens improves your vision the best.

Visual Field Tests

• The visual field test checks your eyes for issues with peripheral vision. It is important that you can see everything in your visual field when you fix your gaze in one direction. The results of this test can assist in diagnosing eye disease or problems with your nervous system. There are three parts to this test.

  The first part is the confrontation test in which your doctor will be positioned two or three feet in front of you. You will be required to cover one eye at a time while focusing on the doctor's nose. The doctor then moves their finger to the edge of your visual field, to the center and to the opposite edge. Still staring at the doctor's nose, you will be asked to give a signal when you are able to see his finger. The same test is repeated with the other eye. In the Amsler grid test, a chart consisting of a 4-inch square with boxes formed by straight lines and a black dot at the center is used. Your eye care professional will hold it about a foot from your face. While covering one eye you will be asked to focus on the black dot. The test is then repeated with your other eye. During this test you should tell your doctor if you cannot see the dot, if you see spots other than the black dot or if the lines on the grid are blurred or distorted.

  In the perimetry visual field test, a machine administers random flashes of lights to various points in your visual field. While you stare at the center of a bowl-shaped instrument, you will be asked to press a button when the lights appear. Computer monitoring of your responses then produces a printout showing places in your visual field where you did not see the light.

  The last visual field test is called a tangent screen test. In this test a black screen with a figure similar to a bull's eye is placed three to six feet away from you. You'll cover one eye and stare at a specific point on the screen. Different objects of different sizes are placed on a wand and moved from the outside edge of the screen toward the center. As you indicate when the object is visible to you, the point is marked on the screen. The points are then connected to create an outline of your visual field. You will then repeat the test with your other eye.

Color Vision Test

• The color vision test determines if you're able to recognize colors and will reveal If you are colorblind. Military and law enforcement careers, as well as some jobs in electronics routinely require this testing. When this test is administered, you will be presented with a sample of the symbols and patterns you can expect to see during the test. Sitting and covering one eye, your doctor will hold a color test approximately 14 inches away from you. When the patterns are held up you will be asked to identify the symbol or pattern that you see. Not all of the cards presented will have a hidden symbol or pattern. If you don't see anything, you should report this. You will then repeat the test with your other eye.