Vision Tests
Guide
How It Is Done continued...
Color vision tests check your ability to distinguish colors. In the most commonly used color vision test, you look for different colored numbers or symbols hidden in varying backgrounds of colored dots.
First, you are shown sample patterns and told what symbols and numbers you can expect to see. You then sit at a table and cover one eye. The doctor holds the color test patterns about 14 in. (36 cm) away from you. Some patterns are harder to pick out than others. As the doctor holds up a pattern, you will identify the number or symbol you see and trace it using a pointer. Some patterns may not have a number or symbol. The test is then repeated with the other eye.
How It Feels
You should not feel any discomfort during these vision tests.
When dilating eyedrops are used
Dilating drops may make your eyes sting and cause a medicine taste in your mouth. You will have trouble focusing your eyes for up to 12 hours after your eyes have been dilated. Your distance vision usually is not affected as much as your near vision, though your eyes may be very sensitive to light. Do not drive for several hours after your eyes have been dilated. Wearing sunglasses may make you more comfortable until the effect of the drops wears off.
Risks
In some people, the dilating eyedrops can cause an allergic reaction.
Results
Vision tests check many different functions of the eye. Your doctor will let you know if your eyesight is normal or if it is better or worse than normal. He or she may also be able to tell you why you have a vision problem.
Visual acuity testing
The visual acuity score compares your distance vision with that of people who have normal vision, using an eye chart. Each eye's score is expressed as two numbers, such as 20/20 (6/6) or 20/100 (6/30). The first number is the distance you stand from the chart, usually 20 ft (6 m) when using a typical wall chart. The second number is the distance from which people with normal eyesight can read the same line on the eye chart.