The third eyelid:
The eyes of all cats have nictitating membranes; these are commonly known as the third eyelid. Located between the inside corner of the eye and the lower lid, the purpose of the third eyelid is to both remove dust from the cornea and keep it moist. In your domestic cat the best times to see this effect are when the animal blinks (this may be infrequent and occur only every few minutes).
Comparison to humans:
Interestingly, the day vision of a tiger is worse than that of man and this is due to the same things that make the vision of cats so much better than us at night.
Day-vision animals need to see sharp, clear images; any reflection from the back of the eye, such as that provided by the tapetum, blurs what is seen and detail is lost.
In day-vision animals (including man) the eye is pigmented, as against reflective. Consequently light which passes the rods and cones is absorbed.
Our high concentration of cones not only gives us our colour vision, but also provides us with the ability to perceive great detail in high light levels.
The red-eye effect:
The "red-eye" effect, often seen in photographs taken using a flash, is a reflection from the back of the eye. It displays as red because of the extensive blood vessels in this area.
| Hearing & Ear Spots | Eyesight
| Smell | Teeth
| Communication | Flehman
| Genetics |
With Thanks To Tiger