Colour Vision and Occupation
Colour Blindness
The term colour blindness is a common but misleading term that implies total loss of colour vision. In most cases the defect is usually only partial and the term “colour defective vision” would be more appropriate. The commonest defect is in the red/green part of the visual spectrum. Males are more commonly affected; about 8% of all males and 0.5% of females are affected to a varying degrees. There are other defects due to failure in the blue receptors, a total failure of all receptors and a failure of the other retinal receptor, the rod
Mechanism of defect
All colours can be made by mixing the three primary colours; red, green and blue in varying amounts and the eye sees colours by detecting the amounts of these primary colours. This processing is done by special nerve endings in the retina of the eye. One type of nerve ending, the cone, has three special pigments which detect one colour, either red, green or blue. If one of these nerve types is impaired there is a colour defect.
Males are more affected because the genes that control the development of these colour sensitive nerve endings are carried on the x chromozone, which is the chromozone that determines male characteristics. Females are rarely affected, but may be carriers of the trait and up to one in seven are carriers.
Colour defects can also be acquired and a common cause in our community is cataracts. As the cataract becomes more dense it filters out all colours, but the bright reds, yellows, greens and blues are more affected. It has been said that the changing colour choices of many famous painters has been due to the affect cataracts have had on their colour vision. Other diseases affecting the optic nerve and the retina also affect colour vision but these are rare and often only affect one eye.
Type of Defects
The defects are named after the Greek words for the three primary colours: Protos for red, Deutros for green and Tritos for blue. Someone who has a complete red defect is said to have Protanopia and if he only has partial defect he is said to have Protanomaly. The commonest defect involves the green receptors and it accounts for over half of the defects; 4% of all males have a partial defect and 1% have a complete defect. As the loss of colour vision is in the middle of the visual spectrum this defect causes the least awareness. The problem is the inability to distinguish red and green but they are sensitive to red light.
The next most common defect is due to failure in the red receptors, and it affects 1% of males. These people also confuse red and green but are not sensitive to red light.
There are other defects due to failure in the blue receptors, a total failure of all receptors and a failure of the other retinal receptor, the rod
Colour Vision and Occupation
Colours are constantly used to distinguish the difference between objects in everyday life. For many centuries colour has been an important part of many occupations and professions. Today the use of colour and colour coding has become much more widespread, a fact that undoubtedly influences the career choices of those with a colour vision deficiency. The use of colour extends to the work environment, and so it affects jobs and careers which require some degree of colour identification. These careers vary in the extent of reliance on colour vision, and so have been grouped into categories depending on if it is desirable or vital for operatives to have normal colour vision. This list can never be comprehensive and many jobs fall into several categories, as there are often different activities within a specific trade, profession or occupation.
Careers/Jobs/Occupations/Industries requiring perfect colour vision.
- Armed Forces (British)-
- Air Forces – certain grades
- Navy – certain grades
- Army – certain grades
- Civil aviation
- Colour matcher in dyeing, textiles, paints, inks, coloured paper, ceramics, cosmetics.
- Carpet darner/inspector, spinner, weaver, bobbin winder
- Electrical work –
- electrician
- electronics technician
- colour TV mechanic
- motor mechanic
- telephone installer
- Navigation – pilot
- fisherman
- railways
- Police – certain grades
Occupations/activities where defective colour vision may be an asset Camouflage detection.
Careers/Jobs/Occupations/Industries where defective colour vision is a handicap and important consequences might result from errors of colour judgment.
- Air traffic controller
- Buyers – textile
- yarns
- tobacco
- food e.g. fruit, cocoa, timber
- Car body resprayer, retoucher
- Cartographer
- Ceramics – painter/decorator of pottery
- Ceramics – inspector (quality control)
- Chemists and chemicals – laboratory analysis
- food chemist
- teacher of chemistry
- manufacturer of chemicals and polishes and oils
- Colour printer, etcher, retoucher
- Colour photographer
- Colour TV technician
- Coloured pencils/chalks/paints manufacturing
- Colourist/colour matcher in paints, paper, pigments, inks, dyes, wallpaper
- Cotton grader
- Coroner
- Forensic scientist
- Market gardener e.g. fruit
- Meat inspector
- Oil refining
- Paper making
- Pharmacist
- Plastics
- Paint maker and distributor
- Restorer of paintings/works of art
- Safety officer
- Tanner
- Tobacco grader
Careers/Jobs/Occupations where good colour vision is desirable, but defective colour vision would not necessarily cause a handicap.
- Accountant
- Anaesthetist
- Architect
- Arts – graphic
- commercial advertising
- Auctioneer
- Barmaid/Barman
- Bacteriologist
- Baker
- Beautician
- Botanist
- Brewer
- Butcher
- Builder/Brick Layer
- Buyer – textiles
- yarn
- tobacco
- food e.g. fruit, cocoa, timber
- Carpenter
- Carpet/lino fitter/planner
- Chiropodist
- Clothes designer
- Cook or chef
- Coroner
- Confectioner
- Cosmetics director (stage, film, TV)
- Dental surgeon and technician
- Draughtsman
- Dressmaker
- Driver Instructor
- Driver in public services e.g. bus
- Engineer (various)
- Farmer Fishmonger
- Florist
- Forester
- Furrier
- Gardener and landscape gardener
- Geologist
- Gemologist e.g. setting stones, diamond grader
- Grocer
- Hairdresser
- Horticulturist
- Illumination engineer
- Interior decorator/designer/planner
- Jeweller
- Librarian
- Lighting director (stage, film, TV)
- Manicurist
- Metallurgist
- Milliner
- Miner
- Nurse
- Optometrist/ophthalmologist/orthoptist
- Osteopath
- Painter
- Pharmacist assistant (counter service)
- Physician
- Physiotherapist
- Post Office counter assistant
- Potter
- Salesman/woman (fabrics, drapery, yarns, wool carpets)
- garments/footwear
- china and glass
- linen
- cosmetics/toiletries
- jeweller
- confectioner
- stationer
- storekeeper
- Shoe repairer
- Surgeon
- Tanner
- Tailor
- Telephone switchboard operator
- Theatre/stage props manager
- Veterinary surgeon
- Waiter
- Window dresser
- Zoologist
Career Advice:
When occupational advice is given, the risk of an error being made and the consequences of the possible errors must be estimated. This is done by first testing the person and then, from the results, determining their suitability to the particular profession. In some occupations the use of colour, and the complexity of its use may increase as a person is promoted, therefore the job may have no prospects for someone with a colour deficiency. This has to be considered when a person with a colour deficiency is hired and should also be explained to the person before they accept the job. Another point to consider is if the person may want to transfer, there is a possibility that although the work may be exactly the same at another company, they may have different policies on hiring people with colour deficiencies.
Day-to-Day Problems:
Most defective colour vision does not seriously handicap those suffering from it in day-to-day life, this is because they adapt to their deficiency and most have normal visual acuity. However, some problems arise in tasks that people with normal colour vision take for granted. Judging the ripeness of fruit, selecting coloured clothes, choosing decorating materials, checking if meat is cooked, reading maps and playing sporting games such as snooker are just a few of many examples. Probably one of the most hazardous day-to-day problems is in driving. Traffic signals are the only connotative colour codes which people use regularly and, although many colour deficient people are able to distinguish traffic lights by the position and different intensities of lights on the column, some do report having problems. About a third of colour deficient people feel uncomfortable driving at night due to the overhead street lights. The street lights can often cause colour confusion and small lights are often mistaken for red stop signals. Red and green ‘cats-eyes’ which mark the lanes of motorways are also often confused. Regardless of the possible complications of driving that colour deficient people have, statistics have shown that colour deficient drivers are involved in fewer accidents, a fact that suggests that they learn to adapt to their difficulties by taking more care.
