Eye charts are used to measure visual acuity, which is the ability to see details at a distance. The most common type of eye chart is the Snellen chart, developed in the 1860s by Dutch ophthalmologist Hermann Snellen. This type of eye chart is used for children who are too young to read or for adults who have difficulty reading or speaking. Other types of eye charts include the LogMar chart, the Landolt C, E chart, the Lea test, the Golovin-Sivtsev chart, the Rosenbaum chart, and the Jaeger chart.
The Snellen eye chart contains several lines of capital letters, with the largest letter in the top row. During an eye exam, the ophthalmologist will ask you to look for the smallest line of letters you can see and read it. If a person, especially a young child, is unable to cooperate with visual acuity tests through an eye chart, doctors can be alerted to possible visual acuity deficiencies by asking parents if the child seems to see well. Optotype is another term that could define an eye chart and is still the most common test for evaluating standard vision.
Practically, this is achieved by covering one eye with one hand, a piece of paper, or a small palette. For this test, the child sits in a chair 10 feet away from the board, gently holding an eye mask over one eye. Modern optometric examination rooms are equipped with electronic eye reading tables, making it easy to produce accurate readings. Depending on what your ophthalmologist is trying to measure, the Jaeger chart can be used in two different ways.
If you don't wear glasses or contact lenses, your ophthalmologist will use the results to see if you need them.Eye charts do not provide doctors with information about eye diseases such as glaucoma, retinal problems, or loss of peripheral vision. Eye charts don't help the ophthalmologist determine if you have an eye disease or a retinal problem. He took his time with me and always asked me ahead of time if I was okay with the eye test I was about to have.