Rod cells are one of the two types of light-sensitive cells in the retina of the eye.Sclera: the white part of the eye, a tough covering with which the cornea forms the external protective coat of the eye.Optic nerve: leaves the eye at the optic disc and transfers all the visual information to the brain.This area is also known as the 'blind spot’.
The optic disc identifies the start of the optic nerve where messages from cone and rod cells leave the eye via nerve fibres to the optic centre of the brain.
Optic disc: the visible (when the eye is examined) portion of the optic nerve, also found on the retina.When the eye is directed at an object, the part of the image that is focused on the fovea is the image most accurately registered by the brain. Fovea: forms a small indentation at the centre of the macula and is the area with the greatest concentration of cone cells.Macula: a yellow spot on the retina at the back of the eye which surrounds the fovea.The retina works much in the same way as film in a camera. There are between 6 and 7 million cones in the eye and they are essential for receiving a sharp accurate image and for distinguishing colours. Cones, on the other hand, function best in bright light. The human eye contains about 125 million rods, which are necessary for seeing in dim light. It is composed of light sensitive cells known as rods and cones. Retina: a light sensitive layer that lines the interior of the eye.Ciliary body: the part of the eye that connects the choroid to the iris.It also contains a pigment that absorbs excess light so preventing blurring of vision. Choroid: the middle layer of the eye between the retina and the sclera.A cataract is when the lens becomes cloudy, and a cataract operation involves the replacement of the cloudy lens with an artificial plastic lens. It is enclosed in a thin transparent capsule and helps to refract incoming light and focus it onto the retina. Lens: a transparent structure situated behind your pupil.The cornea contains no blood vessels and is extremely sensitive to pain. It refracts the light entering the eye onto the lens, which then focuses it onto the retina. Cornea: the transparent circular part of the front of the eyeball.The iris controls widening and narrowing (dilation and constriction) of the pupil. Pupil: the circular opening in the centre of the iris through which light passes into the lens of the eye.Light enters through a central opening called the pupil. It forms the coloured, visible part of your eye in front of the lens. Iris: regulates the amount of light that enters your eye.