Human beings are able to see things because of the interaction of various parts of the optic organs. The eyes, the optic nerves and the brain are the main organs that govern a person's ability to see. The quality of a person's vision is associated with the quality of his or her eyes. In human beings there are several factors such as age and genetics which affect the refraction angle in the eyes. This causes blurred vision. A vision test is aimed at measuring a person's quality of vision. Degradation of the optic nerve system or brain related problems are different and must be tested for by a doctor using various diagnostic tools at his or her disposal. A home vision test can also be conducted for the purpose of measuring the quality of vision. Almost every vision test is designed to measure the relative inaccuracy of the refraction in the eye. These inaccuracies are corrected using eyeglasses or contact lenses, depending on the person with the problem.
There are a few different types of home vision tests. The first test is an adaptation from the standard vision chart test that one might find in an eye doctor's clinic. The subject is made to stand at a specific distance from a vision chart that has a set of lines on it with text printed. Each subsequent line is smaller and corresponds to a level of vision acuity. The line marked 20/20 is the line that corresponds to perfect vision; that is the individual can read and perceive details of an object 20 feet away from a distance of 20 feet without any assistance. If the vision is 20/40, for example, it means that the subject needs to be 20 feet away to properly see something that he or she should be able to see clearly from 40 feet away.
The same test as described above applies for near vision problems. Most people will suffer from near vision reading problems when they grow older. This is sorted out by using reading glasses. The near vision eye chart can be read and the vision acuity of the individual can be judged based on the ability to read each line. Both the above tests can be used to test one's spectacles or contact lenses as well. This is done by performing the test with the glasses on and making sure that the line for 20/20 vision is clearly visible.More articles from the Medical Tests Category