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How the eye works and refractive errors in Eyes

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The human eye is like a camera in that it possesses a focusing ‘lens system’ at the front and has a light sensitive ‘film’, the retina, at the back.

As with a camera, there is a variable ‘auto-focus’ system – the crystalline lens – which allows us to focus on whatever interests us.

Cornea – the window of the eye

A curved dome of strong, clear tissue on the surface of the eye. Cornea is one of the most critical components of the eye. The purpose of cornea is to bend, or refract light rays so that they focus on the retina at the back of the eye. Refractive errors occur when the cornea fails to focus light rays precisely on the retina. LASIK eye surgery is used to improve these refractive errors


A thin protective layer for the cornea which heals very quickly when disturbed.


The coloured part of the eye is actually a muscle that controls the size of the pupil.


The black circular area in the middle of the eye. Like the camera’s aperture it controls the amount of light reaching the retina.


A membrane on the inner wall of your eye, similar to the film in the camera, the retina changes light into images that are transmitted to the brain via the optic nerve.


The outer white coat of the eye, the sclera also provides protection.


A natural lens behind the iris changes shape to allow the eye to focus. As you age, the natural lens hardens resulting in presbyopia – the loss of ‘reading vision’.