Tag: human eye and defects of vision

Through a process called accommodation, this lens helps the eye automatically focus on near and approaching objects, like an autofocus camera lens. Light focused by the cornea and crystalline lens (and limited by the iris and pupil) then reaches the retina — the light-sensitive inner lining of the back of the eye.

cilliary muscles,contraction and relaxation changes the focal length of eye lens to focus the image of an object at varying distance.

Cone cells, or cones, are one of three types of photoreceptor cells in the retina of mammalian eyes(e.g. the human eye). They are responsible for color vision and function best in relatively bright light.

Human eyeball is spherical in shape. Its diameter is about 2.3 cm

The image formed on retina do not fade away instantaneously but its impression remains on the retina for about $\frac{1}{16}s$, even after removal of the object.

The space between cornea and eye lens is filled with a viscous liquid called aqueous humour and the space between eye lens and retina contains a transparent jelly called vitreous humour.

Nature has provided eyes with eyelids to protect them from any object entering the eyes. It also shut off the light when not required.

The photoreceptors in the octopus retina are located in the inner part of the eye while the cells that carry information to the brain,are in the outer portion of its eye.

Rods and cones are light sensitive cells. Rods respond to different degrees of brightness and darkness. Cones respond mainly to colour of the incident light.

Blind spot position varies in both eyes. Octopus do not have any blind spot.A point in our eyes where no image is formed,that point is known as blind spot.