AM I SUITABLE?

Few of us have perfect eyesight and many of us suffer refractive errors so we have to rely on contact lenses or glasses to correct our eyesight. There are four types of refractive error: short-sight, long-sight, astigmatism and presbyopia. In a normal eye with perfect vision an object is naturally in focus at the back of the eye (on the retina), as the object moves away or comes closer the eye can change its focus by a process called accommodation. With short-sight, long-sight and astigmatism the length or shape of the eyeball differs from the eyes' natural focusing power.

Short-sight
Also known as myopia, short-sight is when the eye can only see things in focus close up. This happens because the natural focusing power of the eye is different to the length of the eyeball and the object is focused in front of the retina.

Long-sight
Long-sight, also called hyperopia, is when the eye can only see things clearly in the distance. This condition exists because the eyeball is too short for its focusing power and the object is focused behind the retina. Many people have reasonably good vision as the natural accommodation of the eye can compensate for this. However the eyes' natural ability to accommodate decreases with age, and many people become dependent on spectacles by their mid-thirties.

Astigmatism
Astigmatism refers to a state where the front of the eye, instead of being equally curved in all directions, is more curved in one direction, rather like a rugby ball. Almost everyone has some degree of astigmatism, but for someone with significant astigmatism objects at all distances will appear blurred.