Color blindness is a condition that affects many people across the world. It is important to note that color blindness does not necessarily indicate a complete absence of color perception. It usually means that an individual is less sensitive to particular colors or shades than a person with normal vision. In most cases, a colorblind person suffers from an inability to distinguish shades of green or shades of red. Other than this, they tend to perceive most colors accurately.
Color blindness appears to be an inherited problem which is passed through to a child from an affected parent. The problem has been narrowed down to the 'X' chromosome. A woman may have a defective 'X' chromosome but have normal color vision whereas her son might inherit the abnormal color vision from her.
For adults, the standard method of testing is to use the Ishihara plates testing technique. The Ishihara plates are plates that contain various colored dots on them. The dots around the plate are of different shades of the same color. Within this plate, there is usually a shape or a number depicted by different shades of another color. The area between the dots is left blank white. A person is then asked to tell the tester what is seen. A colorblind person will not be able to notice the number or shape on some of the discs but will be able to notice them on other discs. This is a very basic and yet very effective method of testing an individual for color blindness. This test does only apply to adults who are literate and cannot be used for children.
A color vision test for children uses different testing techniques. For children who are able to understand shapes, a test similar to the one mentioned above is used, but the numbers are replaced with shapes. Although this is less accurate (it is easier to distinguish a shape than a number), it is very useful and fun for children who are taking the test. Some schools insist on this test while for others it is not mandatory. Early diagnosis of the problem could be useful because it helps the child as a student. A lot of the teaching that occurs at a young age involves the perception of colors. A child who is unable to perceive colors should not suffer because of the lack of ability in color perception.