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The human eye, despite all its complex nature, can be described and compared to a modern photo camera
The human eye consists of several components which work in tandem with the aim to efficiently capture light and turn it into an image in the brain.听Light enters the pupil of our eye, much like听light听enters the听front of听a听camera. Our pupils act as a natural aperture, increasing or decreasing in diameter to capture听more or less light听from our surroundings as needed. This change in pupil size is governed by the muscles of the iris, the coloured part of the eye in which the pupil is the central opening. The iris can be compared to the shutter of a camera, as it controls how much light is able to enter through the pupil.听听
Before light enters through our pupil, it听passes听through the transparent part of the eye known as the cornea. The cornea听is a transparent structure with no blood vessels, which听acts as the primary focusing power of the eye, bending听light听so that it听converges听on听the retina听to听form an image. Once light is refracted by the cornea it travels through听the pupil into an听anterior chamber full of aqueous humour, a liquid providing听essential nutrients to the eye. Light then meets another transparent structure behind the pupil known as the lens. The听shape of the lens can be altered by a group of muscles, collectively听known听as the ciliary body,听changing听the听precise听point of light focus on the retina. Like a camera, the lens helps us to focus light when looking at close objects, or those at a distance.听The focused light then travels through听a large听vitreous chamber filled with a transparent gel-like protective substance, the vitreous humour.听听
Light then听reaches the light sensitive part of the eye, the retina. The retina is a highly complicated structure which can be best thought of as the film of the camera. The retina听is responsible for taking light and developing it听into听electrical听information,听which can be sent to the brain via the optic nerve to听enable us to see听an听image correctly.听The retina is supported by the choroid, a rich blood vessel network听that听supplies the retina with听the听oxygen and听nutrients听required to keep the retina working.听The retina听and choroid are physically separated by a barrier of cells, known as the retinal pigment epithelium (RPE)听
