This development of lenses started by the quest for the treatment of optical defects of the cornea with a device is given to the great Italian, Leonardo da Vinci. Between the years 1500 – 1508 marked beginning of the development of contact lenses. Master Leonardo filled a bowl with water, then placed a man’s face into it. It is said that for the first time the individual was able to see clearly. There are two very important factors about this discovery. Improved refraction and improved peripheral visual acuity.
Lens was made by Leonardo da Vinci with a funnel on one side so that water could be poured into it. But due to impracticability, the idea was immediately discarded.
Renee Descartes, a French scientist, in 1636, after reviewing Leonardo’s work, in a special medical treatise, Ways of Perfecting Vision, described a concept of a lens placed directly onto the eye. He developed a tube he could fill with water and place directly against the cornea. This was also discarded on the grounds that it lacked practicality.
The introduction of anesthesia in 1884, contact lens technology advanced because moulding was made possible in the 19th century that wearable contact lenses started to evolve. Glass contact lenses that fit the anterior of the eye, called scleral lenses, were invented by Adolf Fic, Eugene Cult and August Mueller, independently in the early 1880’s. This first lens was made by F. A. Mueller in 1887.
As early as 1912, Scleral glass lenses were primarily manufactured by Carl Zeiss Company in Jiena, Germany. Over the course of about sixty years, scleral lenses made of glass were the major contact lenses used.
Theodore Obrig developed manufacturing techniques for making plastic lenses and suggested the use of fluorescein dyes to study the morphology of the lens fit against the patient’s cornea in 1937. With the introduction of polymethylmethacrylate (PMMA) a flush fitting sclera. These lenses also had desirable cosmetic effects. Innovations greatly contributed to the success of contact lenses, for both cosmetic and therapeutic use.
Plastics produced lenses that were lightweight and very transparent became available in the 1930’s. This eventually changed the course of contact lens technology. They were chemically consistent, stable, unbreakable, scratch resistant and much easier to manufacture.
Kevin Touhy, an optician from England, introduced the corneal lens, which covered only the transparent portion of the protective coating of the eye (the cornea) in 1947. They were much more attractive and easier to wear than the glass and plastic scleral lenses that preceded them. The lenses, patented by Touhy in 1948, rested directly against the limbal margin of the cornea. These lenses had diameters of 10.80 to 12.50 mm.
The new contact lenses could be worn in all kinds of weather and were useful for sporting activities of all kinds. Because the contact lens was large, but smaller than earlier scleral lenses, it was not easily dislodged or lost. Many changes were rapidly introduced to these types of lenses until a product emerged that was safer and could be worn all day, had tremendous optical clarity and was invisible to the human eye. These changes allowed early contact lens patients to address the public with confidence.
At this point, the renaissance in the contact lens field was about to explode. The year was 1960. Celebrities, athletes, business executives, and political figures, all wanted these new contact lenses. Eventually these people, along with students and office workers formed the bulk of the contact lens consumers and popularized contact lenses. Although there were thousands and thousands of converts to contact lenses they really did not threaten to make spectacle lenses a historical footnote.
These lenses had a thickness of about 0.20 millimeters. Thinner lenses of about 0.10 millimeters were introduced in the early 1960’s Remembering that the contact lens renaissance began in 1948, the world was just learning about these new and different contact lens designs. In 1950, George Butterfield introduced the concept of fitting the peripheral cornea. The first corneal lenses to have widespread success were designed in the 1950’s by Frank Dickenson, Wilhelm Sohnjes and John Neil.
It had extreme elasticity when wet, but was still strong and able to hold its shape. In 1958, Otto Wichterle, who was in charge of the Macromolecular Institute of the Czechoslovakian National Academy of Science, along with Dr. Drahoslav Lim, a polymer chemist, developed a new soft plastic that could be cut down or moulded into a variety of shapes. However, when this plastic was placed in water or any type of aqueous solution this tough, rigid plastic became very soft, pliable and increased in diameter. In the wet form it could be bent between the fingers until the edges met, but would snap back to its original shape. This material was subjected to rigorous biological testing and found to be inert and fully compatible with human tissue.
In 1960, the National Patent Corporation acquired the rights to this new, soft plastic and sub-licensed it to Bausch and Lomb for manufacturing purposes. Original problems with this material were that it was not oxygen transmissible, it was hydrophilic, and after some time clogged with impurities from the patient’s lacrimal system. This lens material also was noted to have extreme reactions to different atmospheric conditions, such as increased humidity swelled the lens, while less humidity caused the lens to become contracted on the patient’s cornea.
Chemical composition of lenses
According to Contact Lens Spectrum, all contact lenses utilize a polymer backbone. A polymer is a chemical chain formed from linking many smaller molecules. Contact lenses can be categorized as soft conventional hydrogel, silicone hydrogel, or rigid gas permeable contact lenses.
Soft conventional hydrogel
This polymer serves as the base for all soft contact lenses, and different brands are formed by injecting differing amounts of water and other chemicals into the contact lens as it is manufactured. Soft conventional hydrogel contact lenses share a common backbone of the polymer polyHEMA.
Silicone hydrogel
Silicone rubber is used as the polymer backbone in silicone hydrogel contact lenses. Other chemicals, such as polydimethylsiloxane, are also added to improve comfort. Silicone hydrogel contact lenses are also known as breathable contact lenses. These contact lenses can be worn overnight in some cases.
Rigid gas permeable
Rigid gas permeable contact lenses contain differing amounts of methyl methacrylate, fluorine, silicon and other chemicals to make them comfortable to wear Rigid gas permeable contact lenses are also known as hard contact lenses.
References
Meta Pesona (2011). Chemical Composition of Contact Lenses. Retrieved from http://matapesona.blogspot.com/2011/11/…/ on 18th April, 2015.
Nick, S. (2010). A History of Contact Lenses. Lancaster: Edward Hand Medical Heritage Foundation.