How Eyes Work

  • Eye functions like a camera.
  • Parts of the eye work with light in different ways.
  • Refractive errors occur when light from a distance is not focused correctly on the retina.
  • Various types of refractive eye surgery to correct errors.

Normal functioning of the eye

A normal eye functions like a camera. The cornea is the clear window at the front of the eye. Along with the natural lens inside the eye, the cornea works to focus light coming from a distance clearly on to the retina at the back of the eye. The retina is equivalent to the film in the camera and changes light into electrical impulses that are carried by the optic nerve to the brain.The iris (coloured part of the eye) acts like the aperture of the camera, regulating the amount of light getting in.

An eye in which the light from a distance is not focused correctly on the retina has what is called a refractive error, and requires correction from either glasses or contact lenses to bring the image into focus.

WA Laser Eye Centre performs various types of refractive eye surgery to correct the different types of refractive errors listed below.

  • Short-sightedness (Myopia)
  • Long-sightedness (Hyperopia)
  • Astigmatism
  • Presbyopia
  • Other refractive problems


Short-Sightedness (Myopia) Or Near Sightedness

If the cornea and lens are too strong, or if the eye is too long, then light will be focused in front of the retina. Objects in the distance are blurred but those closer are in focus.

Nearly 25% of people in Australia are myopic. This usually develops while the eye is still growing during childhood or adolescence and stabilises when full growth is reached.

Long-Sightedness (Hyperopia) Or Far Sightedness

Hyperopia is a little harder to understand. Objects in the distance are seen more clearly, while those up close are blurred. The cornea is too flat, or the eye is too short, and light is focused behind the retina.

The mechanism that is usually used to do the extra focusing for seeing up close has to be used even to see in the distance.


Astigmatism refers to the condition where the cornea has different curvature. It does not have equally rounded curves like a basketball, but has unequal curves, more like a football.

This makes focusing uneven or distorted and objects are not seen clearly whether they are up close or in the distance. Many people with myopia or hyperopia have some degree of astigmatism as well.


Gradual inability to focus on near objects with age.

Presbyopia is often confused with hyperopia (long-sightedness). It is part of the normal process of ageing and occurs when the lens inside the eye gradually loses its ability to bring objects up close into focus. The effects of this usually start between 40 and 50 years of age.

People who have presbyopia will benefit from having an assessment at our centre as we have some new treatment options available. Some people are suitable for monovision correction. That means having one eye corrected for distance and the other for reading vision. Some people may also be suited to multifocal intra-ocular lenses which restore near and far vision and may be a treatment option for those individuals with presbyopia.

Other Refractive Problems

Other conditions such as keratoconus or corneal scars can affect the focusing of the eye. Certain individuals who were previously not suitable for LASIK may now be able to have treatment. Schedule an appointment today to see if you are a candidate.

The final decision as to which type of refractive surgery is best for your requirements will be made after consultation with our centre.

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