An Invisible Alternative to Glasses

by Joshua Wasps

It's reckoned that 125 million people use contact lenses everyday. For many, it's an invisible alternative to glasses, which serves the same purpose without changing the appearance of the face. Contacts provide a wider field of vision and do not steam up, as well as being more suitable for sporting activities. They are also used to help treat medical conditions, such as keratitis, which causes abrasions on the cornea which a porous, bandage contact lens can help protect against.

The earliest contact lens principle can be attributed to - who else? - Leonardo Da Vinci, but it was never intended for the purpose of correcting vision. In his Codex of the Eye, Manual D of 1508, he describes how to affect corneal power by immersing the eye in a bowl of water; the objective of his studies was to better understand the mechanisms of the eye, and how it focuses - this is called accommodation. Rene Descartes developed the idea in 1636 by filling a glass tube with water, which would then sit on the cornea. This proved impractical, however, as it would obstruct blinking, but there was at least a general understanding that refracting light in some way changed the accommodation of the eye.

In 1801, scientist Thomas Young, whilst studying accommodation, made an -eyecup- filled with liquid, which could be regarded as the forebear of the modern contact lens. Again, the device could not be used as a vision aid, and it was not until 1887 that F.E. Muller, a German glassblower, produced the first lens that could be tolerated by the eye. His design rested on the rim around the cornea, and was made from brown glass, but the lenses were unwieldy and could only be worn for a few hours.

Glass-blown lenses remained the only form of contact lens until the development of Perspex in the 1930's. William Feinbloom, an optometrist, introduced a glass/Perspex combination lens, which was much lighter and more comfortable and convenient than the pure glass lenses.

Technology improved over the next thirty years to allow smaller, corneal lenses (rather than early designs which covered the entire surface of the eye), and by the 60's, contact lenses had gained mass appeal as a viable alternative to spectacles. However, these early Perspex lenses allowed no oxygen to get through to the cornea, which, whilst improving vision, could have an adverse clinical effect on the health of the eye. Permeable designs were developed throughout the 70's and 80's, but the biggest breakthrough was the introduction of the soft lens, by Czech chemist Otto Wichterle. These were much more comfortable, and before long superceded the Perspex and glass lenses. More recently, silicone hydrogels have been used in the manufacture of even more comfortable, oxygen-permeable lenses.



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