What Are Contacts?
Contacts are dome-shaped pieces of plastic used to correct vision by reshaping the eye. Eyes mold to fit the shape of the contact, thereby correcting the way light rays converge on the retina. To know how a contact works one must first understand how an eye works.
How an Eye Works
Light reflects off objects to form images on the back of the eye, the retina. Single light rays meet up at points on the retina. When these light rays converge to a single focal point on the retina, then the image is clear.
Bad Vision
Most vision problems occur when light rays do not converge to a single focal point on the retina, which is usually caused by an odd shape of the outer layer of the eye or the cornea. Blurry images form when the focal point of the light is either in front or (nearsightedness) or behind the retina (farsightedness). Other problems can be caused by the eye having two focal points (astigmatism).
Correcting the Vision
When placed in the eye, contacts mold the cornea for the exact shape needed to redirect the focal point to the retina. Images then appear clear. There are two main types of contacts--soft and hard. Hard contacts give the most accurate vision because the contact holds the shape of the eye firmly. Soft or bendable contacts often give a distorted vision because they cannot hold the shape of the eye as firmly as hard lenses. In recent years soft contacts have become more popular because of their comfort and retention of oxygen and moisture on the surface of the eyeball.
Some History
The initial idea of contact lenses was developed by Leonardo Di Vinci. Although he never created one, he described and sketched the concept in his journals. It wasn't until 1887 that the first functional contact lenses were developed by F.E. Muller, a glassblower in Wiesbaden, Germany. In 1945 contact lenses were formally accepted by the AOA (American Optometric Association) as an integrated part of the optometrist practice. By this time contacts were safer, with the introduction of plastic into contact lenses. Newer, more accurate ways of fixing eye problems via new ways of measuring personal eye shape for a better fit were also developed.
