Zorro laughed well recently when he saw me looking for the ladybird which I had down on the nose ; he even dared to say that I needed glasses ! This ladybird was just outside my field of vision, that’s all…
The cats eyes are made to spot the slightest movement. Our vision field is bigger than that of human : human covers approximately 210o (120o binocular), and we cover approximately 285o (130o binocular).
Proportionally to the size of our head, we have big eyes.
Our pupillary reflex to the variation of luminous intensity is extremely fast : only big cats of the Felis genre can retract their pupil to the size of a slender vertical crack. We can dilate it also considerably to see better at night.
We are able to distinguish colors, but less well than humans : we are little sensitive to red, and we could say that our vision of tints is more pale. This is due to the structure of our eye cells : we have more rod cells (night-vision in black and white) than cones (diurnal and colored vision). We are diurnal and crepuscular predators, thus our eye is perfectly adapted to our nature.
Two erroneous assertions have nevertheless firm existence :
- Cats see in total darkness.
WRONG. Cats need from five to six times less light than humans to see during the night, but they cannot see in total darkness.
- The eyes of cats shine in the dark.
WRONG. Our pupil is dilated to receive the tiniest rays of light in the darkness. Cells situated behind the retina act as a mirror to amplify the light and allow us so to see better when it’s dark, what seems to make our eyes shine.