How the eye works

The eye is like a camera, and a camera needs a lens and film to generate an image. In the same way, the eyeball needs a lens (cornea, crystalline lens and vitreous humour) to refract or focus light and film (retina) upon which rays are focused. If one or more of these components do not work correctly, the result is a blurry image. When we look at an object, rays of light are reflected from the object to the cornea.

From there, they move through an aqueous fluid and go through a small opening called the pupil. When the muscles of the iris relax or contract, the pupil changes in size in order to adjust the amount of light that enters the eye. Rays of light are focused using the lens and go through a clear, gelatinous substance in the centre of the eye called the vitreous humour. This substance is what gives the eye its shape.

The purpose of the lens is to refract rays of light on the retina. The retina would represent the film of our camera; it is in charge of capturing the image and of sending it to the brain to “develop it”. The resulting image appears in the retina backward.

In the retina, rays of light become electrical impulses that are transmitted through the optical nerve to the brain, where they are translated into an image and perceived the right way around.

The macula is responsible for centring the vision. It is the part of the retina we use most, since it is used for things such as reading or looking closely at an object.

Anatomy of the eye musculature

They are known as extraocular muscles (EOMs). The main role of the four straight muscles is to control the lateral, ascending and descending movements of the eye.

The two oblique muscles move the eye to rotate it inward and outward.