PLASTIC CONTACT LENSES (LATE 1940s)
Acrylic began to replace glass as the contact lens material of choice in the late 1940s. These were manufactured from PMMA rods or buttons which were turned into lenses via lathing operations. Stiff, wettable and durable, the new material proved a major success, and is still used in the manufacture of 'hard' contact lenses today. The development of 'soft' lenses was the next major advance. This began in the 1960s when Otto Wichterle discovered pHEMA hydrogel and a technique for turning it into contact lenses. He polymerized the monomer in a spinning mould, such that the rate of spin dictated the optical qualities of the lens. The result was a highly effective and comfortable lens that prompted a wave of research into alternative hydrogels and the launch of many competing products.