COLOR BLINDNESS
Color blindness is not a form of
blindness at all but a deficiency in the way one can see color. Color-blind
people have difficulty distinguishing certain colors such as blue and yellow or
red and green.
Color blindness or more accurately, Color Vision deficiency, is an inherited condition that affects males more frequently than females. An estimated 8 percent of males and less than 1 percent of females have color vision problems.
Red green color deficiency is the most common form of color blindness. Much more rarely, a person may inherit a trait that reduces the ability to see blue and yellow hues. This blue-yellow color deficiency usually affects men and women equally.
Color blindness: Signs and symptoms
Contrary to popular belief, it is rare for a color blind person to see only in shades of gray. Most people who are considered “color blind” can see colors but certain colors appear washed out and are easily confused with other colors, depending on the type of color vision deficiency they have.
Color blindness testing can help determine the kind of color deficiency you have. Commonly Ishihara Charts and Lantern tests are performed for screening for color blindness.
What causes color blindness?
Color blindness occurs when light-sensitive cells in the retina fail to respond appropriately to variations in wavelengths of light that enable people to see an array of colors.
Inherited forms of color blindness often are related to deficiencies in certain types of cones or outright absence of these cones.
Besides differences in genetic makeup, other causes of color vision defects or loss include:
- Parkinson’s disease (PD)
- Cataracts
- Certain medications. For example, an anti-seizure drug called tiagabine has been shown to reduce color
- Leber’s hereditary optic neuropathy (LHON). Red-green color vision defects primarily are noted with this condition.
- Kallman’s syndrome. This inherited condition involves the failure of the pituitary gland. Color blindness can be one symptom of this condition.
- Color blindness also can occur when aging processes damage retinal cells.
- An injury or damage to areas of the brain where vision processing takes place also can cause color vision deficiencies.
Color Vision defect and Maritime Industry
The maritime industry is a fast growing and dynamic field with many opportunities that are crucial to the transportation industry and world economy; people turn to the oceans for resources such as food, transportation and energy.
Color Blindness in the maritime industry can be a struggle. Seafarers working at sea may be required to identify lights and signals. If they have a color vision deficiency, this important part of their job could be impossible to do. There are also a multitude of symbols, signs, markers, maps and other signals that maritime officers must be able to quickly identify, evaluate and navigate which requires them to accurately see colors. Hence, any color vision defect is unacceptable amongst sea-farers. Before joining sea and frequently thereafter seafarers are screened for color vision defects while they undergo Medical examinations.
Unfortunately, because of lack of awareness, there are many people who are fooled into believing that all color blindness can be corrected with surgery and medication.
Even though glasses and lenses that allow correction in color vision have been developed, for seafarers and pilots these aids are not allowed and the person is considered unfit for navigation.
For many maritime careers one must pass a series of physical tests and requirements, one of which is the Ishihara Color Vision Test, or one of the other exams that are almost identical to it