How a Customised Autoclave Helped a Contact Lens Manufacturer to Solve a Packaging Problem

摘要

Contact lenses have been used for eyesight correction for over a century. Actually it was Leonardo da Vinci who first illustrated the concept but, like so many of his ideas, the technology wasn't available to produce them at the time. Although it is hotly debated to whom the credit belongs, the first contact lenses manufactured from glass, and fitted to cover the entire eye were manufactured in the late 1880s. Glass has obvious shortcomings including discomfort and susceptibility to damage and, by 1939, lenses were being manufactured from polymethyl methacrylate ('Perspex'). These 'hard lenses' were large and, because the material does not allow oxygen to pass through, could only be worn for short periods. In 1948, English optical technician Kevin Touhy demonstrated the first corneal lenses. Smaller, lighter and more comfortable, they set the standard for future lens development. The advent of oxygen-permeable plastics in the 1960s allowed contact lenses to be worn for longer periods and comfort was further improved in the 1970s by the development of 'soft' hydrogel lenses which are hydrophilic and help to keep the eye moist. In the 1990s the development of silicone hydrogels with high oxygen permeability meant that these lenses could be worn overnight. But it is only relatively recently that disposable toric lenses for astigmatism have been possible.