One can see different colours by the combination of three colours, red, blue and green. If one's eyes are weak in seeing a particular colour, intensity of that particular colour is to be increased so that the person can see all the colours. If someone’ s eye is weak to see red colour, this defect is called (AIIMS Nov 2012)
1. Protanomalous = defective red colour Qperception
2. Deuteranomalous = defective green colour Qperception
3. Tritanomalous = defect blue colour Q perception
4. A chromatic colour vision Q (Total colour blindness)
5. Conditions resulting from congenital absence of the cones, It is associated with day blindness (Hamarlopia) and nystagmus
6. Acquired macular disease tends to produce-blue yellow defects and optic nerve lesions -red - green defect
7. *Blue blindness - may occur in old age Qdue to increased sclerosis of the nucleus lens.