Colour blindness

A colour-defective male always inherits his deficiency from his mother, who usually has normal colour vision and is therefore a carrier of the defect. She may have received her colour deficiency gene from either her father (but only if he was colour defective), or from her mother (who could have been a carrier herself, or rarely, who was colour-defective).

It is important to remember that people with colour blindness generally can see most colours; they just have trouble distinguishing between some shades of red and green.

Can it be corrected?

Colour blindness is not correctable. However, there are some devices (coloured contact lenses or filter spectacles) that are claimed to improve the vision of colour blind people but in general, people report very mixed results with them. There is currently no effective way to recover full three-colour vision if you are red/green colour blind.