Parts of the Eye

a transparent window that refracts incoming light to focus on the retina, helps the eye focus as light makes its way through

the black hole in the iris that allows light to enter the eye.

The coloured part of the eye, changes size to control the amount of light entering the pupil (adjusts the size of the pupil)

refracts light to focus the image on the retina. Ciliary muscles thin out when focusing on distant objects, and thicken when focusing on near objects

Light-sensitive cells (rods and cones) change light energy into nerve impulses. Flips the image, the brain turns it back around

Takes messages from reti a to the brain

a tough, protective, white outer layer that protects the eye.

the black layer of blood vessels that provides nutrients

helps keep the eyes shape, and provides the medium for the light to travel through. Watery at the front and jelly-like at the back

A type of photoreceptor that sees in black and white, and shades of grey and tells us the form something has. Allows us to see when very dark

Senses colour and requires more light than rods to work well. Sensitive to primary colours; red, blue and green, which together can sense combinations of light waves that let our eyes see millions of colours.

• Nearsightedness • Can see close up, not far away • Caused by a too-long eyeball or a cornea that is curved steeply • Diverging lens (concave) diverges light before it reaches the eye, then it is converged by the concave lens to produce an image on the retina

• farsightedness • can see distance, not up close • caused by a too-short eye, or flat cornea • Convex lens bends light rays towards one another before the concave lens bends it even more to create an image on the retina.