Colour blindness is a disorder in which the individuals affected have a partial or total inability to detect certain wavelengths of the visual spectrum. Colour blindness varies between individuals in both the insensitivity and the wavelengths they are unable to see. There are several different defects and they are named after the Greek word for the primary colours: protos for red, deutros for green and tritos for blue. Someone with a complete red defect is said to have protoanopia and if he has partial defect they are said to have protoanomaly. The most common defect involves the green receptors and leaves people unable to distinguish red and green, but still sensitive to red light. The next most common failure is in the red receptors. These people also confuse red and green but are insensitive to red light. Less common are failure of the blue receptors, total failure of all receptors and failure of the rods.
There are certain jobs that require the ability to distinguish between colours. Whether or not an individual with colour vision defects is capable of doing a particular job depends on the degree of the defect and the importance of accurate colour distinction to the job function. It is best not to enter into employment where colour discrimination is an important factor or where it affects career prospects in the future. On the other hand, there is no point in ruling out a particular career if the disability is mild and manageable. It is important to establish the degree of disability and then make a decision. Some of the professions where colour blindness restricts employment are: Armed Services (some branches); Customs & Excise; Civil Aviation – pilots, engineers, technical & maintenance staff, air traffic controllers; Railways - drivers, engineers & maintenance staff; Fire Service; Hospital Laboratory Technicians and Pharmacists; Workers in paint, paper and textile manufacture, photography and fine art reproduction.