- particular shades of reds and greens (most common) or
- blues and yellows (less common).
What causes color vision deficiency?Usually, color deficiency is an inherited condition caused by a common X-linked recessive gene, which is passed from a mother to her son. But disease or injury damaging the optic nerve or retina can also result in loss of color recognition. Some specific diseases that can cause color deficits are:
- macular degeneration
- Alzheimer’s disease
- Parkinson’s disease
- multiple sclerosis
- chronic alcoholism
- sickle cell anemia
- Medications – certain medications such as drugs used to treat heart problems, high blood pressure, infections, nervous disorders and psychological problems can affect color vision.
- Aging – the ability to see colors can gradually lessen with age.
- Chemical Exposure – contact with certain chemicals such as fertilizers and styrene have been known to cause loss of color vision.
How is color vision deficiency diagnosed?Color deficiency can be diagnosed through a comprehensive eye examination. Testing will include the use of a series of specially designed pictures composed of colored dots, called pseudisochromatic plates, which include hidden numbers or embedded figures that can only be correctly seen by persons with normal color vision.
- Pseudoisochromatic testing plates. The patient is asked to look for numbers among the various colored dots, which help distinguish between red, green and blue color deficiencies. Individuals with normal color vision will see a number, while those with a deficiency do not see it. On some plates, a person with normal color vision may see one number, while a person with a deficiency sees a different number.
How is color vision deficiency treated?There is no cure for inherited color deficiency. But if the cause is an illness or eye injury, treating these conditions may improve color vision. Using special tinted eyeglasses or wearing a red tinted contact lens on one eye can increase some people’s ability to differentiate between colors, though nothing can make you truly see the deficient color. Most color deficient persons compensate for their inability to distinguish certain colors with color cues and details that are not consciously evident to people with normal color vision. There are ways to work around the inability to see certain colors by:
- Organizing and labeling clothing, furniture or other colored objects (with the help of friends or family) for ease of recognition.
- Remembering the order of things rather than their color can also increase the chances of correctly identifying colors. For example a traffic light has red on top, yellow in the middle and green on the bottom.