Eye Care - History of Contact Lenses
Contact lenses might seem like a relatively recent innovation to you and me, but they were in fact a meandering thought in the mind of Leonardo da Vinci as long ago as 1508. When he thought that putting a lens directly on the eye could aid in vision and gave detailed descriptions and drawings in his notebooks to that effect. But unfortunately, as with so many of his other brainwaves (like the helicopter for example) his ideas were way beyond the means of his time to actually do much about, and so they remained firmly in his head or notebooks. Rene Descarte also suggested the corneal contact lens (as opposed to covering the whole eye) in 1632. And Thomas Young did work on optics around 1801 to develop Descartes' idea - through demonstrating that by using a quarter-inch-long, water-filled glass tube he could correct his own vision.
However, in practical terms the ideas largely floundered until English astronomer Sir John Herschel suggested techniques for grinding and fitting a contact lens to conform exactly to the eye's surface in the 1820's. He also suggested taking a mould of the eye to ensure accurate fitting; and this was something that finally became possible in 1884 with the development of anesthesia. Then in 1887, F. A. Muller, in Germany, a maker of artificial glass eyes, made a transparent lens to protect a diseased eye which was apparently used for years. However, these early lenses were very heavy and could only be worn for very short spaces of time. The first true contact lens as we might recognise it was developed in 1888, by A E Fick, a physiologist in Zurich, who put Herschel's mould idea into practice. Basing his design first on moulds made from rabbit eyes, then from cadavers before finally making himself some glass contact lenses to correct his own vision (He also came up with the name 'contact lens'). Even this though was something of a false dawn, because it soon became clear that eyes and glass weren't a match made in heaven. They were very uncomfortable to wear, and in the event he only wore that original pair for two hours.
Approaching the twentieth century then, Contact Lenses science had levelled off. There were certainly glass lenses that were being made to address specific therapeutic requirements. And because moulds could now be taken, they even fitted fairly well. But in general contact lenses were heavy, uncomfortable, and because the glass impeded the flow of oxygen to the eye; not particularly good for the general longer-term health of the eye.
What Fick did succeed in doing however was opening Pandora's Box to the potential uses for contact lenses, both therapeutic and cosmetic. And over the next century eye specialists and chemists were engaged in a constant pursuit to find the perfect materials to use for lenses. A process which is far from complete even today, with innovations if anything coming thicker and faster then at any other time. Because what seems like a simple problem at first glance. "Design the best lens to fit over an eyeball to correct vision". Is actually multi-layered. What material can correct vision and also allow oxygen to get to the eye? What is a safe length of time to wear lenses? Can a single shape of lens adapt itself efficiently to fit all manner of eyeballs? Is the material durable and non-toxic enough to be used? And any number of other questions that are still puzzling researchers to this day.
The next real breakthrough came in 1938 when the first all plastic contact lenses were made by Obrig and Mullen in the United States (Feinbloom produced a partially plastic lenses in 1936) using a new material, polymethylmethacrylate (PMMA). Which was vastly superior to glass in weight, safety, workability and comfort. (Interestingly, bowling balls are also often made out of this stuff!) These were however what are termed "scleral lenses", meaning that they covered the whole eye. This was adopted for glass lenses, because typically it would aid in stopping the lenses from falling out (because glass is heavy this was an important consideration) which did mean that oxygen couldn't get through to the eye, and that chances of disease, inflammation etc were greatly increased.
The modern contact lenses as we know it was born in 1947 with the progression from plastic scleral to plastic corneal lenses by American Kevin Tuohy i.e. lenses that only covered the cornea of the eye, rather than the whole eye. It is these types of lenses that we typically know as "hard" contact lenses (think of what glass must have been like to wear in comparison!) and for the next two decades were virtually the only type of contact lenses to correct refractive errors in vision. As you can imagine they were a big hit in Image-Conscious Hollywood, and early adopters included future US President Ronald Reagan.
The problem though with PMMA lenses was that although a vast improvement over glass, it was still a non-permeable material. And hence was still uncomfortable to wear, and didn't allow oxygen to the cornea. The next major step forward came with the development in the 1950s by Czechoslovakian polymer chemist Otto Wichterle and colleague Drahoslav Lima of a new, transparent hydrogel plastic called hydroxyethylmethacrylate, made up largely of water, that had the unique characteristic of being hard when dry but soft and pliable when wet. Thus was the "soft" contact lenses born! It was not however an easy birth, because being soft and permeable, they were comfortable on the eye, but their water content made them difficult to handle, initially of poor optical quality, and raised questions about the absorption of infectious bacteria. And so it was not until 1971, and considerable research expenditure and development of a new manufacturing process called “spin casting", that Bausch & Lomb finally obtained approval from the U.S. Food and Drug Administration (FDA) to sell hydrogel ("soft") lenses in the United States.
Since 1971 the sales of the "soft" lenses has predictably vastly overtaken "hard" lenses, and many more manufacturers have stepped in to supply the demand. According to the Vision Council of America there are 136 million American adults who wear prescription eyewear in the United States. This represents 66% of the total U.S. adult population - 43% of whom are men and 57% are women. Retail sales of contact lenses (excluding eye exam fees) in the U.S. were $1.9 billion in 2001, representing 12.3% of the total market's retail eyewear sales. And according to the Bureau of Labor Statistics, there were 67,800 opticians in the United States in 2000. So this is a vast market!
In keeping with the size of the market the innovations have continued with pace. 1979 saw FDA approval for 'gas-permeable hard lenses' which allowed oxygen to reach the cornea through the lens as soft lenses do, while also offering the optical clarity and ease of handling of hard lenses (though not necessarily the same level of comfort). (The market share split between the various types of contact lenses is currently approximately 82% soft lenses - 16% gas permeable - 2% hard lenses). The first tinted soft lenses came on the market in 1980. Extended wear contact lenses in 1981 (initially approved for 30 days continuous use - but later changed to 7 by the FDA because of health concerns). Bifocals in 1982. The first disposable soft contact lens was in 1987. The first disposable tinted soft lenses in 1992. And Daily Disposables first came on the market in 1995. The latest innovation in Contact Lenses is the October 2001 FDA approval for Extended Wear Soft Lenses that are approved for wearing for a continuous period of thirty days. The principal difference between these and the 'Daily' disposables being in the level of oxygen that the lens allows through to the cornea of the eye. After the issues of 1981 though, it is perhaps worth being cautious and consult carefully with your optician before deciding to proceed with them.