Eyeglasses through the Years

Eyeglasses have made known to everyone for the past centuries. This invention has been of great help for people since then up to the contemporary period as it goes along with its innovative specs. But even up to this date, the inventor of glasses and lenses are still unknown. No evidence exists to prove the identity of the inventor of eyeglasses, but many lay claim and believed to be the inventor of it. Roman tragedian Seneca (4 BC -65AD) have allegedly used a glass globe of water as a magnifier to read ''all the books of Rome''. And others stated that the monks in the middle ages used glass spheres as magnifying glasses to read. Meanwhile, Venetians glass blowers are known to have produced reading stones made of solid glass that was put into hand-held, single lens-type frames made of horn or wood during the 13th century and was similar to hand-held magnifying lenses of today.

Historians believe that around 1285-1289, the first form of eyeglasses was produced in Italy by monks or craftsmen in Pisa (or perhaps Venice). It was thought that Salvino D'Armate was its inventor. Salvino D'Armate is most often credited with the invention of the first wearable eyeglasses around 1284 and was prescribed for hyperopia. These magnifying lenses for reading were shaped like two small magnifying glasses and set into bone, metal, or leather mountings that could be balanced on the bridge of nose.

Ancient Chinese were credited for inventing sunglasses. In the 12th century Chinese sunglasses were made from panes of smoky quartz used to dim the light. Inuits used walrus ivory to create goggles with small slits to peer through. Later during the 18th century, English optician James Ayscough, who originally created spectacles with tinted lenses, which he thought could improve vision, created sunglasses which were similar to what we wear today.

Spanish craftsmen in 1600's made the first eyeglass frame temples. They affixed ribbons of silk or strings to the frame and loop them over the user's ears. The new types of eyeglasses carried out to China by Spanish and Italian missionaries. Chinese attached small metal weights to the strings instead of making loops. In 1730 Optician Edward Scarlett designed rigid temples that rest atop the wearer's ears. Bifocal lenses can be used to treat with nearsightedness and presbyopia [with a lower part for viewing objects near at hand (as in reading)]. It was first devised by Benjamin Franklin in 1784.

Concave and convex lenses principle were familiar to the people during 17th century. Eyeglasses can be produced with single lenses that correct for distance vision or up close, or they can be manufactured with multifocal lenses, which correct both distance and reading. Concave glass is used to correct nearsightedness, so that the rays of light are diverged while convex lenses are used to aid the correction of farsightedness, so that the light rays are converged. Cylindrical lenses used to correct astigmatism were invented by Sir George Airy in 1825.

By the 1800s, eyeglasses were common, but not as we think of them today. Lenses weren't custom made; instead, you'd go to a jeweler, a hardware store, or meet with a traveling peddler to try on different pairs of eyeglasses until you found the ones that worked. And because eyeglasses were seen as a sign of old age, people often opted for handheld devices such as lorgnettes (spectacles with a single handle on one side) or scissor spectacles (where lenses moved on a hinge) instead of wearing glasses all the time. In the mid-1850s curl sides were invented, which were curling wires that went behind the ears. Curl-side frames were especially common for children's eyeglasses because they stayed in place while running or playing.

At the end of the 18th century, Philadelphia store proprietor John McAllister the founder of the profession of optician in this country opened the first optical shop in America. When the War of 1812 and the trade embargo with Great Britain hindered his importing ability, he began making his own frames out of gold and silver. He and his son also imported the first cylindrical lenses for astigmatism.

Various styles and types of glasses followed, including reading glasses, glasses for farsighted and nearsighted, anti-radiation glasses, sunglasses with different tints and fashionable glasses that are trend in this century.

IMPACTS OF EYEGLASSES

Eyeglasses build a name for itself for the past years, bringing a lot of impact to different aspects in the society and environment. Below are the following:

 Social Impact

During the 15th to 16th century, there was an exponential increase in demand for spectacles due to availability of printed materials, i.e. books and newspapers. From that era, it was evident that people treated wearing eyeglasses as a status symbol. This was because the early eyeglasses were possessed by churchmen, wealthy scholars, artisans, and high-class individuals of the medieval world. Hence, people in Spain, Italy and China regarded eyeglasses as a sign of superior intelligence and nobility, a symbol of wisdom and learning.

The start of eyeglasses being a fashion statement was in 1880 when monocles were popular. Aristocrats commonly used monocles as status symbol and fashion statement.

From the 20th century onwards, eyeglasses have shifted from a want into a need for those whose vision needed correction as the production cheapens. People started to view eyeglasses as a medical necessity. According to the Vision Council of America, approximately 64% of adults wear eyeglasses. In addition, eyeglasses as a fashion statement started to gain popularity. A sizeable number of people wore eyeglass frame for fashion purpose. The innovation of sunglasses also contributed to the increase in popularity.

Despite more of the population having access to eyeglasses, there are still social issues whereby people from the developing countries do not have access to eyeglasses. According to VisionSpring, there are approximately 700 million people who need but don’t own eyeglasses.

In a study on the impact of eyeglasses on the academic performance of primary school students in rural China, a very low percentage of students who needed glasses actually owned a pair of glasses. The study also found out that after about 8 months of wearing glasses, children’s test scores improved by 0.16 to 0.22 standard deviations, which is equivalent to 0.33 to 0.50 years of additional education.

 Economic Impact

The invention of eyeglasses has increased productivity over the ages. In the past years, active and productive members of society had to stop working, writing, reading and using their hands for skillful tasks at a relatively young age. With eyeglasses, these members were able to continue their work.

In the modern age, studies had showed that there is a direct correlation between proper vision correction and productivity. This relationship particularly is evident with complex and/or repetitive computer tasks such as data entry. Computer-related tasks took much longer when the subjects wore glasses with less than the optimum correction. There was reduction in productivity even among computer users who were unaware that they had vision problems.

Computer users with small refractive errors may not noticed any vision discomfort. But without proper vision correction, their performance on a specific task can suffer significantly by as much as 20 percent.

The economic impact of this invention was not identified in the 17th-20th Century, only being measured in recent time. However, from the recent studies, it still shows that the use of eyewear has good economic impact relating to the productivity of the worker because they had an eyewear that helps them to see and do their work better. Another economic impact is the need and the invention of eyewear that has led to the dominance of a company in the eyewear industry.

 Technological Impact

Sunglasses; Ballistics eyewear; Google glasses; 3D glasses; Makeup glasses; Computer glasses; Chroma; Smart glasses for the blind; VR glasses are some technologies that have evolved from the invention of the eyewear. The creation of frames allowed for the work of newer technology to be added on to the original design for specific purposes.

MATERIALS USE FOR EYEGLASSES

In the past, the production of eyeglass lenses relied on separate optical laboratories. Today, there are a lot of full-service optical outlets that produce lenses for customers on-site. However, optical outlets do receive lens "blanks" plastic pieces already formed to close-to-exact size with different curves ground into the front of the lens from optical laboratories. Blanks with different curves are used for specific optical prescriptions.

The plastic blanks received from optical laboratories are round pieces of plastic such as polycarbonate approximately. 75 inch (1.9 centimeters) thick or thicker and similar in size to eyeglass frames, though slightly larger. Most finished eyeglass lenses are ground to at least 25 inch (.63 centimeter), but this thickness may vary depending upon the particular optical prescription or "power" required. Other materials used to produce eyeglass lenses are: adhesive tape, a liquid with a lead alloy base, metal, dyes and tints.

Eyeglasses frames are typically made of either metal or a type of plastic called cellulose-acetate. Cellulose acetate is derived from cotton and is flexible and strong. It is produced in long narrow sheets that are slightly wider than eyeglass frames. The sheets are up to 3 ft. (0.91 m) long and 0.33 in (0.84 cm) thick.

Lens materials for glasses are glass, plastic or polycarbonate. Glass was the original material for spectacles because it has great optical clarity, but the glass lenses can be very heavy in stronger prescriptions. Plastic lenses are much lighter than glass but they are prone to easily being scratched. The lightest and thinnest lens material for glasses is polycarbonate, also called CR-39.

TYPES OF LENSES

 Single Vision Lenses

Single vision lenses are the most basic type of lens. Unsurprisingly, they also tend to be the least expensive. Made for correcting one field of vision (near or far), they offer the largest visual field of any lens type.

 Photochromic lenses (Transition) Lenses

Also known as transition lenses, photochromic lenses darken when they come into contact with UV rays. This eliminates the need for sunglasses, increasing convenience and minimizing expense for the wearer.

They are technically not a prescription type, but rather a treatment added to prescription lenses. Note that the lenses will darken even on cloudy days, which some may find inconvenient. However, they are often a popular choice as they add a little style to your glasses.

 Bifocal & Trifocal Lenses

Usually wear by oldies. These lenses correct a wider range of more severe vision issues.

Bifocals and trifocals are lenses that have two and three powers apiece, respectively. They are sometimes referred to as multifocal even though this technically refers to progressive lenses.

All within one lens, it has separate sections for near and distance correction, which makes them a versatile choice. Those requiring intermediate vision correction will be prescribed with trifocals that have a third correction too.

The drawback of bifocals and trifocals is that there are lines separating each section, which makes for drastic changes in vision correction when you move your eye inside the lens.

It’s something that you learn to work with, but the inconvenience paved the way for advances in lens technology such as progressives.

 Progressive Lenses

Progressive lenses perform the same job as bifocals and trifocals, but in a different way.

They work around the dividing lines of bifocals, which was a known inconvenience glasses wearers dealt with for many years. The actual visual field within progressive lenses is smaller than that of bifocals or trifocals. This may help to explain why we still see many older folks wearing trifocals as opposed to progressive lenses.

Overall, progressive lenses offer the same fields of vision correction but without the lines. Transitions from near to intermediate to distance correction are much smoother.

 Screen or Computer Lenses

These are special-purpose eyeglasses meant to optimize your eyesight when you’re looking at digital screens. They are designed to: reduce glare (a major cause of eyestrain), increase contrast and maximize what you see through the lenses-making it easier to look at a screen for longer periods of time.