Colour blindness

Colour blindness is used to describe any impairment in colour perception. It may be inherited or acquired.

• in the most common form, there is poor discrimination of red and green. This is inherited in an X-linked recessive manner and is seen in about 8% of men and 0.4% of women
• blue-yellow discriminatory failure is more commonly an aquired form of colour blindness; both sexes are affected equally
• diagnosis:
  • it can be tested for using appropriately coloured-book plates such as those used in the Ishihara test

Acquired defects of colour vision are seen predominantly in macular and optic nerve disease, and may complicate inherited retinal dystrophies particularly those causing abnormal cone function.