Optometrist Sydney – Colour Blindness
Colour Blindness is a vision condition where different colours look the same, or look very similar. There are several variations on this, with one of the most common being individuals unable to tell the difference between red and green. Colour blindness is almost always a genetically inherited condition, but on rare occasions it can be the result of damage to the eye. There is no known cure, but there are some ways to at least partially compensate for milder forms of colour blindness.
Optometrist Sydney – The Physiological Causes
Humans have 3 different colour receptors in their eyes, as well as receptors that see in black and white. These three colour receptors correspond to red, green and blue, though there is some slight overlap. All the various colours we can see are a different combination of these three colours sensed by the corresponding receptors in our eyes.
In many colour-blind people the overlap between the different receptors is larger than normal, so perhaps a green object will simultaneously activate both the red and green receptor in the eye. This will cause red and green colours to look similar, sometimes even identical.
Alternately, in some colour-blind people a receptor is missing, so they cannot see a certain primary colour at all. In a few extreme cases of colour blindness the receptors do not work at all, and the individual sees in black and white.
Some type of colour blindness:
Deuteranomaly – Green colours look more red. This is the most common type of colour blindness, and has minimal impact on lifestyle.
Protanomaly – Red looks more green. This has minimal impact on lifestyle.
Tritanomaly– Blue and green look similar. Yellow and red look similar. This is fairly rare.
Protanopia – Red receptor is missing. Red and green look the same.
Deuteranopia – Green receptor is missing. Red and green look the same.
Tritanopia – Hard to distinguish blue and green, purple and red, or yellow and pink. Colours also look less bright.
Achromatopsia – All vision is black and white. No colour receptors.
Glasses for the Colour Blind – Optometrist Sydney
While colour blindness cannot be cured with present technology it is possible to partially compensate for some types of colour blindness. This is achieved with glasses that filter out some narrow bands of coloured light. The principle is to filter out the area where the receptors overlap. If we filter out the overlap between red and green light then the receptors will not be simultaneously activated. Red light will activate the red receptor only, and green will activate the green receptor only. This means red and green will now appear to be different colours, though unfortunately the eyesight of a colour-blind individual will still not be the eyesight of a person with normal vision.
Eyesight is important. Have your eyesight checked to correct any problems before they become too serious.
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