Dr. Charles H. Williams was a Harvard medical grad specializing in ophthalmology. His extensive education in the field of ophthalmology allowed him to hold positions in relevant departments of railway companies. While head of the medical and insurance division of the railway system, he designed a lantern for detecting color blindness that may have been present in railway workers. Motivation for this invention was brought about by the belief that many engineers suffered from color blindness. This belief was due to the large amount of tragic train wrecks in the 1800's. Since then, there has been many variations of the lantern test.
Individuals who suffer from color blindness are unable to differentiate between certain color patterns, combinations of color or specific shades of color. While the average eye is able to recognize thousands of color combinations, a color blind eye is limited to certain shades. The William lantern color sense test combines colored slates and lighting used to test for color blindness. Testing is conducted in both dark and light surroundings. Modern technology has made this test more accurate and advanced, allowing it to become one popular method in measuring color visibility while detecting color vision abnormalities.
Many career fields require applicants to take and pass a color sense test. Such tests are critical in fields where signal lights, flags and other navigational tools are needed. Therefore, those who suffer from a color vision deficiency (color blindness) may also be restricted from joining the military, working in transportation or operating certain machinery. For this reason, the Williams lantern color sense test is popular in the railway, aviation and military career fields.
The Williams lantern color sense test is just one of many methods for detecting color blindness. Another commonly used test is the Ishihara test for color blindness. This test is conducted by using several tiny colored dots in a pattern. Each pattern consists of a mixture of colors with a picture of numbers or letters placed in the center. The picture in the center is a different color than the colors that surround it. Blindness to the center image typically indicates potential color blindness.
Although lantern tests are designed to detect color blindness, they do not provide insight as to which kind of color blindness is present. Lantern tests also lack the sophistication needed to measure the severity of the blindness.