Refractive Error

Half of all visual impairment in Australia is due to under-corrected refractive error

This translates into 210,000 Australians having visual impairment due to under-corrected refractive error. This can be eliminated with the provision of proper glasses. This could remove a barrier to independent living.

Types of Refractive Error

Normal vision

In a normal eye, light rays pass through the cornea and lens then focus on the retina in a precise way without blurring - just as a camera lens focuses light onto a film.

The perfect state of focusing exactly on the retina is unusual; the average person is a little hyperopic

Longsighted vision (Hypermetropia)

A longsighted, or hyper-metropic eye is shorter than normal. Light rays focus behind the retina, and close objects look blurred.

Shortsighted vision (Myopia or nearsightedness)

A shortsighted, or myopic eye is longer than normal. Light rays focus in front of the retina rather than on the retina. Distant objects look blurred

Astigmatism

Many people with myopia or hypermetropia also have some astigmatism. Caused by changes in the curvature of the cornea itself, astigmatism distorts the light rays entering the eye and prevents them from focusing clearly

Presbyopia

In addition to the above refractive errors, with age the lens of the eye loses its flexibility and is less able to change its shape to sharply focus the light on the retina. Close tasks such as reading or sewing become more difficult. It is a normal part of the aging process.