Press F11 to hide tool bars

Eye & Contact Lens Factsheets

SMALL ERRORS OF LONG SIGHT
For the patient who suffers with a low error of long sight the need for glasses is often difficult to understand mainly because, unlike a short sighted patient or very long-sighted patient, they often enjoy good vision at both distance and near without wearing spectacles.
Understanding how the eye works and why glasses are needed for such errors, is vital for a person since without a little knowledge sufferers are unlikely to get the most out of their glasses. In extreme cases, because glasses for short sight don't always make things clearer, some may even feel their optician has "Sold" glasses simply for commercial reasons. We have produced this Fact Sheet to ensure that our patients with small errors of long sight are fully informed why they need glasses and how to get the very best from them.
To understand long sight there are certain basic facts to appreciate.

1.
 The eye is like a camera - the internal crystalline lens has to be focused on the object in view to see clearly.
2.
 Normally sighted or not the muscles in the eye, without you feeling anything, are automatically adjusting the focus of your intra-ocular lens all day long just like an auto focus camera.
3.
 The internal focusing muscles work in one direction only. They can correct, or partially reduce an error of long sight, but have absolutely no effect on short sight.
How is it that a person who has a small error of long sight can still see clearly?
Imagine your eye to be just like an auto focus camera. Immediately you open your eyes after sleep the brain registers that distance vision is not as clear as it ought to be. Immediately, and without any sensation the automatic nerve system starts "pulling" the eye's internal lens into the correct curvature to give you a sharp, crisp image.