Difficulty distinguishing between the colours red and green

• Difficulty distinguishing between the colours red and green. • It is the most common type of Colour blindness, and occurs in approximately 99% of cases.

• Colour Blindness is usually diagnosed through clinical testing from an optometrist. • A colour test is most often used to diagnose red-green colour blindness.

Normal Vision Red-Green colour Blind Vision

Normal colour vision: 25 Normal Colour vision: 29 Normal Colour Vision: 45 Red-Green Colour Blind: 25 Red-Green Colour Blind: Spots

Normal Colour Vision: 56 Red-Green Colour Blind: 56 Normal Colour Vision: 6 Red-Green colour Blind: Spots Normal Colour Vision: 8 Red-Green colour Blind: Spots

• The gene for colour blindness is located on the X chromosome. • It is Sex-linked. It is much more likely for a male to be colour blind than a female. • It is a recessive trait.

Example Pedigree: X b. Y X BX B X BY X BX b Legend Male XY Normal vision B XBXB/b X b. Y Colour Blind b Female XX

Layers of the Retinal Rod and Cone receptors in the retinal

• Individuals with this type have a mutated form of the longwavelength pigment. • Individuals with this type have a mutated form of the medium wavelength pigment. • They are less able to recognize shades of red. • This results in a reduction of sensitivity to shades of green. • This form of colour blindness is rare, affecting about 1% of the male population. • This form of colour blindness is the most common, affecting about 6% of the male population.

• Occurs when the individual is lacking the long-wavelength sensitive pigments. • Individuals with this condition find it hard to distinguish between shades of red, yellow and green. • This form of colour blindness affects about 1% of the male population. • Occurs when the individual is lacking the medium wavelength sensitive pigments. • Individuals with this condition are unable to distinguish between shades of red, green, and yellow. • This form of colour blindness affects about 1% of the male population.

• There is currently no treatment or cure for Red -Green colour blindness. • Certain types of contact lenses and tinted filters may help an individual to distinguish between different colours.