An eyesight test can determine the quality of a person's vision and sometimes detect other health issues. There are a variety of these tests that pinpoint specific vision problems. For example, a color test can show if there are problems with color blindness or if a nerve disease may be impairing the eyesight. These tests can be required to obtain a driver’s license or specialized work certificate. An eyesight test is typically a painless procedure that involves reading an eye chart.
One of the most common vision tests is called the Snellen eyesight test, which is given to determine the distance a person can see clearly. A series of letters are placed on a chart, which vary in size. If a person can only see the largest letter clearly, he is said to have 20/400 vision. When he clearly sees the smallest letters, he has 20/20 vision. This does not mean the vision is perfect, it only means that it is average.
An optometrist can use a number of these tests while he is doing an eye examination. The tests can determine if there are any vision problems, and also detect certain eye diseases. They can be used to diagnose brain conditions or systemic disease. Neurological disorders can cause the muscles surrounding the eye to malfunction. An eyesight test may be the only way to diagnose these types of disorders because some have no other symptoms.
If a patient complains to an optometrist about blurred vision, the doctor will typically perform a refraction test. This type of eyesight test is commonly done when corrective surgery or glasses can improve a patient’s eyesight. It consists of doing several vision tests as well as checking for nearsightedness or farsightedness. A refraction eyesight test should be done every few years after the age of 40. Aging can worsen vision problems.
There are other diseases and conditions, which, if left unchecked, can cause vision loss. High blood pressure and diabetes can cause muscle deterioration or glaucoma. Over exposure to harmful ultra violet rays can raise the risk of developing cataracts.
An eyesight test should be given to children at around six months of age. This can detect some learning difficulties. Focusing and distance should be measured, along with hand-to-eye coordination.