General aspects of the eye

There's a lot of confusion about areas such as farsightedness, nearsightedness and reading glasses.

One should distinguish between distance vision and seeing near.

Distance vision is devided into several areas:

• Shortsighted; the eye is too long and/or the cornea is bent too much. The "focal point" is in front of the retina.
• Normal eye; the combination of the cornea and lens bend in such a way to the light that the focal point is on the netvlies.
• Farsighted; the eye is too small and/or the cornea too flat.

These aspects are decided upon by measuring a combination of the length of the eye and the size and shape of the cornea.

Shortsightedness however, is decided upon through the increasing volume* of the lens, especially with age the volume increases, thereby decreasing flexibility which then leads to a decrease in reading capability.

Some anatomical aspects:

• Lens - situated behind the iris, more flexible with age. Varies in accommodation capacity from 25dpt at birth to none at older age. Possible to correct in case of farsightedness up to about 2dpt without any problems.
• Cornea - the clear film situated behind in front of the eye. You can only see it when you look into an eye from the side.
• Corpos Vitreum - thick gel on the inside of the eye.
• Retina – thin membrane situated at the back of the eye. Changes incoming light into electric pulses that are sent through to the eye nerve.
• Eye nerve - the nerve exists of millions of fibres that guide light impulses to the brain.

Being able to see is a very complex procedure. All aspects of the eye have to work together optimally t achieve the best possible vision. Even the slightest variations in this complicated teamwork will affect one's vision.

The most simple problems are refractive defects such as shortsighted, farsighted and astigmatism. These can be corrected with glasses and contact lenses. The severity of the problem is expressed in dioptres.