The Human Eye

The iris: the coloured part of the eye. opens and closes around a central hole to let in more or less light in.

The Pupil: the hole in the iris through which light entres the eye

Lens and Cornea:converging lenses that refract light to form a sharp image.

-corrnea is the transparent bulge on top of the pupil that forces light.

retina: the image is focuse on the retina. Light sensitive cells convert the light signal onto n electronical signal, transmitted to the brain via the optical nerve. the brain flips the inverted image.

**the optic nerve creates a blind spot at the back of the eye**

Eye Accommadation

-eye muscles focus on distant and nearby objects by slightly changing the shape of the eye lenes.

- the focal length is changed, focusung on the image on the retina.

Light from a distant object

- muscles are relaxed, so lens is flat to focus the image on the retina.

Light from a close object

- muscles are contracted, so lens is rounded to focus on the image on the retina.