Glasses are made up of two components. The frame which usually conveys fashion, and the lenses which perform the task of refracting light.
The earliest spectacles were produced by glaziers in Venice, Italy. Lenses in these first eyeglasses were made from quartz or rock crystal and produced by gold craftsmen. The earliest historical figure to wear glasses was Bishop Ugone da Provenza. He was protrayed in a painting in the year 1252, which can be seen in the church of St. Nicolo in Italy. Craftsmen who made these early glasses were called The Cristallerieri, and they had their own ethics code established in the year 1284.
Spectacles were not commonly used until after the printing press was invented by Guttenburg in the mid-1500′s. The written word marked the beginning of the need to correct vision with eyeglasses. The initial lens design was biconvex and corrected presbyopia and farsightedness. Some time later biconcave lenses were made to help the nearsighted. Johannes Kepler discovered the idea of grading lenses by their focal power.
In the 1800′s most glasses were sold in hardware stores. Slowly jewelers succeeded hardware stores as the dispenser of glasses. People who thought they needed glasses would try on one after another until they found the pair that worked for them.
Bausch and Lomb and American Optical were the first companies in America to produce ophthalmic lenses for optometrists. The first lenses they mass produced were glass and later in the 1900′s a material made of plastic was introduced that revolutionized the lens industry.
The lenses in your eyeglasses can be made from different materials. Your optometrist will help you decide which is right for your special needs.
It is the most common choice for lenses typically because it is half the weight of glass. It can be tinted to almost any color and density, and is seven times more impact resistant than glass. Plastic lenses are more easily scratched than glass lenses.
This was the only lens material available up to the year 1943. It’s the most scratch-resistant material, but twice the weight of plastic.
This is the most impact-resistant material available and is the lens of choice for young people and those with an active lifestyle. Polycarbonate lenses are inherently thinner than a standard lens and block all harmful ultraviolet light. This material is difficult to tint.
Photochromic – Lenses That Darken In The Sun
Available in both plastic and glass, this lens darkens when going from indoors to outdoors. These lenses perform well for about three years, then begin to lose their ability to lighten up.
High-Index – Lighter, Thinner Lenses
This lens is available in both plastic and glass. It has the quality of bending light faster. This allows for a thinner design. This is recommended for a person with a strong prescription. Thinner, lighter lenses are more comfortable and look better.
This lens has one power and corrects nearsightedness, farsightedness and astigmatism. They can be used for distance or near activities.
This lens has more than one power, and is used when a person needs one power for distance and a different power for near vision. These lenses are also called bifocals, trifocals and progressive addition lenses. The progressive is a high-tech lens that has a cosmetic advantage because the line does not show – it’s invisible. This lens has the distance prescription in the upper half and the lower half gradually increases in power to provide clear reading vision.
These lenses are relatively new and provide special visual and cosmetic benefits for people with strong prescriptions. They are flatter than conventional lenses and reduce the magnification effect of farsighted corrections thereby enhancing appearance. These lenses are thinner and lighter and allow more peripheral clarity to one’s vision.
Polarized or polaroid lenses offer the most advanced form of sunglasses available. They are made with a special film embedded in the lens which is placed at an angle that cancels reflected light rays allowing only natural light to pass through. They are excellent lenses for drivers, fishermen, hunters and anyone out in snow.
Anti-Reflection Coating (ARC)
Regular lenses reflect from 8-13% of incident light. ARC reduces this reflection to 1-2% resulting in less eye fatigue, better night vision, reduced glare and enhanced appearance.
Plastic lenses can be scratched easier than glass and need a coating to increase their surface hardness. This coating does not make the lens scratch proof but tends to lengthen the life of the lens. This coating is especially helpful with children’s lenses.
Ultraviolet Protection (UV 400)
It is a fact that UV light is harmful to the eye. UV 400 coating allows the lens to block 100% of harmful UV light. Polycarbonate lenses provide this protection without a special coating.