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Origins of Contact Lenses
The first time that the concept of changing visual defects by altering the refractive surface of the eye was conceptualised, was when Leonardo da Vinci (in 1508) took poorly sighted people to the top of a castle and had them immerse their faces in water of different shaped glass bowls. With the right shape for their eye condition, people could see the ground below clearer. That was the first contact lens, but it took well over 300 years before a crude, glass-blown contact lens could be manufactured.
In the late eighteen hundreds, people started fitting glass-blown shells to the eyes in an attempt to correct visual anomalies. The lenses did not fit well and the glass made them very heavy so they tended to sag down.
In 1936 the Rohm and Haas Company discovered a substance, polymethyl methacrylate (PMMA) which is similar to perspex. This was half the weight of glass and could be lathe cut giving much better fitting results. However, these lenses lacked the ability to deliver essential oxygen to the eyes.
In 1952, Wilhelm Sohnges decided to dramatically reduce the diameter of the then scleral lenses to within the diameter of the cornea and thus have the lens float on the front surface of the eye with capillary attraction. Thus the age of rigid, hard corneal lenses was born. Many millions of people were successfully fitted with hard lenses. It has to be one of the great breakthroughs in medical science.
In the late nineties, a Czechoslovakian chemist by the name of Drahoslav Lim discovered poly 2-hydroxyethyl methacrylate material. It required the mixing of two polymers together which set into a gelatinous substrate when wet. This was a hydrophilic (water-loving) material that soaked up to 40% water and expanded. When dry it shrunk into a hard, brittle plastic-type substance. At the same time, Otto Wichterle used poly 2-hydroxyethyl methacrylate polymers in the manufacturing of the first spin-cast soft contact lens.
He ingeniously used his kid’s Makano set, a bicycle dynamo, and a bell transformer to spin moulds into which he injected the liquid polymer. The faster he spun the moulds the more substance would move to the outer edge and thus create a lens of more power.
Merkur-based apparatus for centrifugal casting of contact lenses by Otto Wichterle.
(Source: en.wikipedia.org/wiki/Otto_Wichterle)
“He ingeniously used his kid’s Makano set, a bicycle dynamo, and a bell transformer to spin moulds into which he injected the liquid polymer. The faster he spun the moulds the more substance would move to the outer edge and thus create a lens of more power.”
Due to political restraints, he did this all at home. He was Myopic and fitted himself with the first 4 that he manufactured. He then made a hundred lenses and within 4 months, 5 500 at which stage the Czechoslovak Academy of Science, unbeknown to him, sold his patent to the United States of America and the worldwide soft lens revolution began. If hard contact lenses were a great medical breakthrough, then the soft lens era was explosive. The lenses were very comfortable and could very successfully correct both Myopic (shortsighted) and Hypermetropic (far-sighted) vision. They could not initially correct Astigmatism and so after a while, the euphoria was curtailed and a move back to hard contact lenses occurred. During the soft lens era, many Optometrist students were never taught hard lens fitting which left a gap in the market. PMMA material was improved upon and greater and greater oxygen-permeable materials came onto the market giving the hard lenses a boost in the right direction.
So then, in the eighties until the present date we had soft and hard lenses which could cater to a much wider variety of eye disorders, but not all. It was then in the mid-1990s, that because the rigid lens materials had become so gas (oxygen) permeable, it was possible to start refitting the original scleral design of contact lenses. We had thus gone in a full circle and were fitting what Leonard da Vinci demonstrated in about 1508.
Today we can safely say that we have contact lenses that can be fitted to nearly every poor vision causing condition, thanks to the brilliant minds from the past.
