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VISANTE OPTICAL COHERENCE TOMOGRAPHY

Dr. Edward Boshnick
8479 Coral Way
Miami, FL 33155
(305) 264-4400
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Contact Lenses - Then and Now

It is believed that the great inventor, Leonardo Da Vinci was the first to conceive of contact lenses in the early 1500's. He never actually made a contact lens, but conveyed the idea in his sketches and notes.

In 1637, Rene Descartes used a waterfilled glass tube called a "hydriascope" to neutralize the power of the cornea. It is debatable whether this was used as an early "contact lens" or a prototype that later led to the discovery of the telescope. It seems these two inventors and their concepts were ages before their time, since it was over two centuries before the first scleral contact lenses were designed and used. (A scleral lens is a large diameter contact lens that goes beyond the cornea to cover the white portion of the eye called the sclera). Several men were working on the concept of scleral lenses in the late 1800's, including Adolf Fick, a Zurich physician, Fredrick Muller, a glass blower; and Eugene Kalt, another Zurich physician.

The first designs were made of blown glass shells, and later lathe-cut glass shells.

Blown glass shells were much more comfortable to wear, but they were not optically acceptable. Lathe-cut glass shells gave better vision, but unfortunately were much less comfortable due to the sharpness of the edges. Both of these designs were fit on keratinous patients with limited results. While there was some visual improvement for these patients, poor comfort and comprise to the cornea were still a problem.

In 1934, a plastic called polymethylmethacrylate (PMMA) was invented. This plastic would truly begin to revolutionize the art and science of fitting contact lenses. William Feinbloom utilized both PMMA and glass in an attempt to make a scleral contact lens in 1936. The combination of the two materials was unsuccessful and soon scleral lenses were made exclusive with PMMA. Though PMMA improved the results doctors had with scleral lenses, an "accidental discovery" in 1946 would forever change the way contact lenses were made.

Kevin Tuhoy is credited by most as being the inventor of the "corneal" contact lens. A corneal contact lens is many times smaller than, and certainly no larger than the colored part of the eye (iris). The discovery came when a coworker in his laboratory was showing Tuhoy a scleral lens and how it was designed when the scleral lens accidentally broke. What was left was a small diameter contact lens and continued to refine it until he finally patented it in 1948. Tuhoy's first successful fits included himself and his wife, both of whom were very nearsighted.

PMMA was a better material than glass, but even with the smaller diameter there still problems with corneal contact lenses. Although it is an optically excellent modality, PMMA does not allow oxygen to pass through the plastic. This leads to edema (swelling) of the eye and difficulty with comfortable wearing. While PMMA was better than glass, there was still room for improvement.

In the 1970's, a family of plastics called silicone-acrylates (SA) were first used to make contact lenses. Silicone allows oxygen to pass through the material more easily, and when combined with the excellent optical qualities of PMMA, it made for a plastic that could be fit on the cornea with less edema and increased comfort. Silicone-acrylate materials were a great improvement, but there was still a need for a rigid lens material that allowed even more oxygen to the cornea.

Today many doctors have turned to the newest plastic in contact lenses, the fluorosilicone-acrylate (FSA). Fluorine, when added to the silicone and PMMA of the previous generation materials, will allow and even greater amount of oxygen to the cornea and allows the material to wet better when its in the eye. This in turn enhances comfort to the patient and promotes greater occular health.

Just as materials have continued to improve over the years, so too have the designs with which we work. Bifocal contact lenses, contact lenses for astigmatism (toric designs) and contact lenses for keratoconus have come a long way since glass was first used over a century ago. Those designs coupled with the plastics we now have available allow contact lens patients everywhere to live their lives comfortably and visually uninhibited.

Other topics:
>> Keratoconus and related information including corneal ectasia, corneal hydrops, and pellucid marginal degeneration .