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A Journey through the Lens - Glasses Through the Ages

Eyeglasses are one of the world's most significant inventions, improving eyesight for people with vision disturbances. From the earliest lenses – which were simple magnifiers – to today’s exquisitely manufactured graded lenses with individual prescriptions for every wearer; the advent of the lens has uniquely given human history optimum opportunity to truly see well.

progressive-lenses

History of the Lens

The crudest form of lens was first used in ancient times (c1000) when it was noted that images were magnified if viewed through convex-shaped glass. Franciscan monk, Roger Bacon (1220-1292), experimented with the principal and confirmed that objects could be more easily seen when viewed through a sphere of glass, with the potential for helping weak or ageing eyes.

During the 15th century in Florence, Italy, experiments were being conducted on convex lenses – as well as concave lenses – for the first time. With the knowledge that eyesight declined after the age of 30, spectacle makers were constructing progressive lenses in different strengths, forerunners to today's prescription lenses. Popular and cheap, documents show that literally thousands of spectacles with the new lenses were being exported throughout Europe and spectacle peddlers were a common sight on the streets.

Italy remained the centre of progressive lens development during the 17th century, adding flint to the glass to make the lenses clearer. Eventually rock crystal mined in Argentina and Brazil replaced glass, as it had greater durability. The first tinted lenses were developed – as were bifocals – and round lenses were universally worn for more than a century. In 1797, Englishman John Richardson conceived the idea of four lens spectacles with each lens able to be rotated for different distances. Later the same year, English optician Dudley Adams developed the super orbital patent specs with drop down lenses attached to a headband. In 1825, American Sir George Airy designed the first concave astigmatic lenses for his own myopia.

Eyeglass Lenses Today

Lens technology continues to evolve, with modern lenses often made of complex plastics; which are thinner, lighter, and more scratch resistant than older lenses made of glass. Polycarbonate and trivex lenses are a great choice for sports people, as the lenses are impact resistant and provide UV protection. High index plastic lenses are ideal for people with strong prescriptions who previously had to wear 'coke bottle' glasses. Photochromic lenses change to a darker tint when exposed to sunlight, while polarised sunglasses reduce glare. Aspheric lenses have differing degrees of curvature across the surface, giving the wearer a larger degree of viewing area.

Without the dedication of centuries of lens makers, designers, optometrists, and opticians, we would not have the invaluable lenses today that continually improve eyesight the world over.

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