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Home > Health > Contacts - An Introduction Part II


Contacts - An Introduction Part II: Contact Types and History

Eye and Vision Specialists



There are three different types of eye specialists: ophthalmologists, optometrists and opticians:

Ophthalmologists: Ophthalmologists are Medical Doctors - Md.'s - As doctors they treat diseases or the eye, and perform surgery on the eye.

Optometrists: Optometrists specialize in vision problems. They get their degree from a 'college of optometry' and it is called an OD degree - a doctor of optometry.

Opticians: Opticians are technicians that specialize in the fitting of glasses and contacts. They can not do eye exams.



Contact Lens Basics



A lens is something made to either converge or diverge light, they are usually made from glass or some type of plastic. The cornea of the eye is a lens that refracts (bends) light as it passes through it. An Arab mathematician was the first person to recognize that the lens in the eye forms an image on the retina. Contacts correct eyesight by refracting light to focus it on the retina.

About 60% of the population need vision correcting lenses of some type. About 90% of people have somewhat imperfect vision. And around 34 million people in the U.S. wear contacts.

A converging lens has at least one convex surface and is thicker in the middle - this type of contact lens is used for people who are farsighted or have presbyopia. A diverging lens has one concave surface and is thinner in the middle - this type is used for people who are nearsighted.



Types of Contacts



Contacts are typically divided up by the type of material they are made of. There are three main types: hard, soft and rigid gas permeable.

Hard Contacts: Hard contacts are not worn very much anymore. They were made from polymethyl methacrylate (PMMA), which is the same thing as Plexiglas or Lucite. (When I started wearing contacts I was in the 7th grade, and this is the kind I wore! They were not very comfortable, and I couldn't wear them for too many hours in one day.)

Soft Contacts: Soft contacts are the most commonly worn type of contact now. They are made of water absorbing plastic.

Rigid Gas Permeable (RGP) These are a newer type of contact and are made from silicone polymers. They are worn by around 15% of contact wearers.

Contacts can also be divided into groups based on their typical wearing schedule. This includes 'daily wear', and 'extended wear' contacts. Or based on special needs like toric lenses for people with astigmatism.



A Little Bit of the History of Contacts



The first record of the concept of contacts is from 1508, by Leonardo da Vinci. Apparently he came up with the idea of placeing a lens directly onto a person's eye and actually sketched out his ideas!

Much later in 1632 Rene Descartes the French mathematician, who also studied light and vision, also proposes the idea of placing a lens directly on the eye.

In 1827 the astronomer Sir John Herschel comes up with the idea of creating a mold of a person's eye to make lenses that would fit it perfectly.

In 1887 two different people create the first real, successful contacts: Adolf Fick, a physiologist and F.E. Muller, a glassblower.

Sometime in the 1940's contacts began to be sold commercially. And in 1948 they began to be made of polymethyl methacrylate (PMMA).

In the 1950's the first contacts made with water absorbing contacts. In the 1970's soft contacts began to be sold commercially by Bausch & Lomb. In 1978 the first soft contacts for people with astigmatism were made. In 1979 the first rigid gas permeable (RGP) contacts became available.

In 1981 the FDA approved contacts for wearing overnight!

In the 1990's disposable contacts become available.

Other articles in this series are: Contacts - An Introduction Part I: Eyes and Vision,
Soft Contacts - Daily Wear and Disposable,
Rigid gas permeable (RGP) Contacts,
Daily Wear Contacts,
Extended Wear Contacts and
Orthokeratology.

Some related web sites are History of Contacts and Categories of Contact Lenses - has a nice little graphic illustrating the different types of contacts.






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