Colour blindness and Vision defect

Colour blindness noun - Genetic inability to distinguish differences in hue.

Vision defect and colour blindness are semantically related. In some cases you can use "Vision defect" instead a noun phrase "Colour blindness".

Vision defect noun - Impairment of the sense of sight.

Colour blindness and vision defect are semantically related. Sometimes you can replace phrase "Colour blindness" with "Vision defect", this phrases are similar.