Scotopic vision

Scotopic vision is the monochromatic vision of the eye in dim light. Since cone cells are nonfunctional in low light, scotopic vision is produced exclusively through rod cells so therefore there is no colour perception. Scotopic vision occurs at luminance levels of 10-2 to 10-6 cd/m².

Mesopic vision occurs in intermediate lighting conditions (luminance level 10-2 to 1 cd/m²) and is effectively a combination of scotopic and photopic vision. This however gives inaccurate visual acuity and colour discrimination.

In normal light (luminance level 1 to 106 cd/m²), the vision of cone cells dominates and is photopic vision. There is good visual acuity (VA) and colour discrimination.