The visual acuity test is used to determine the smallest letters that can be read on a standardized chart (Snellen chart) or on a card 20 feet (6 meters) away. Special tables are used when testing at distances less than 20 feet (6 meters). If you're not sure about the letter, you might guess. This test is done on each eye one at a time.
If necessary, it is repeated while wearing your glasses or contact lenses. You may also be asked to read letters or numbers from a card 14 inches (36 centimeters) from your face. This will test your near vision. The Snellen eye chart is the most common method used by eye doctors to measure visual acuity, which is the clarity with which a person can see.
During an eye exam, patients will read the Snellen chart 20 feet away. The lower the patient can read in the chart, the better his visual acuity. The eye chart is used to measure visual acuity, which refers to how well you can see without glasses or contact lenses. The results are used to determine if you need glasses to correct your vision.
It's part of a general assessment of overall eye health. Modern optometric examination rooms are equipped with electronic eye reading tables, making it easy to produce accurate readings. You will be asked to remove your glasses or contact lenses and to stand or sit 20 feet (6 meters) from the eye chart. Donders performed eye exams by having people look at a graphic on the wall and describe what they could see.
The Snellen chart is an eye chart that measures a person's vision by how well they can read and see details. The smallest row of letters that the patient reads accurately determines the visual acuity in the uncovered eye. More than 100 years after its invention, ophthalmologists around the world continue to use the Snellen chart. The Snellen chart makes it easy for eye doctors to prescribe corrective lenses and restore clear vision.
Eye professionals can use certain tables to measure distance vision and others to measure near vision. Using a Snellen chart at home can give you an idea of your visual acuity, but it's not a substitute for an actual eye exam. Snellen's eye chart is read by covering one eye and reading aloud the letters on the chart, starting at the top and moving down. Eye charts don't help the ophthalmologist determine if you have an eye disease, such as glaucoma, or a retinal problem.
You will be asked to cover one eye with your palm, a piece of paper, or a small palette while reading aloud the smallest line of letters you can see on the chart. The visual acuity test is a routine part of an eye exam or a general physical exam, especially if there is a change in vision or a vision problem. Snellen created the standardized eye chart. Every ophthalmologist or eye doctor had a chart they preferred, says Jenny E.
There are several versions of the Snellen eye chart for people, such as young children, who can't read the letters of the alphabet.