Question: Can somebody be colourblind in just one eye?

Elaine Marshall answered on 18 Jun 2013:

At the back of your eye you have specialized cells known as cone cells. You have 3 types which allow you to see colour in bright light. Each cone is sensitive to visible wavelengths of light : red (long-wavelength), green (medium-wavelength), or blue (short-wavelength). Each cone cells contains a photoreceptor which is a protein which detects the light and triggers a signal to the brain.

As the proteins are encoded by genes (which incidentally arose by gene duplication) if you have a genetic mutation which affects the function of a photoreceptor then this will will mean that the mutation will be present in both eyes.

However in some situations it is possible for one eye to be involved e.g. illness or disease, head injury, or some medicines can effect one eye or both.