Introduction for Eyewear

A Brief History

Around the year 1000 glass blowers in Italy are credited with producing reading stones made of solid glass similar to hand held magnifiers used today.

Historians believe around 1285 Italian monks or craftsmen produced the first eyeglasses with magnifying lenses for reading. The lenses were set in bone, leather or metal and joined by an inverted ‘V’ to create a bridge to balance on the nose.

In the 1600’s Spanish craftsmen created the first eyeglass temples. They attached ribbons of silk or string to the frame and looped them over the wearer’s ears.

In 1730, Edward Scarlett, a London optician introduced rigid temples which rest atop the wearer’s ears.

Benjamin Franklin invented bifocal lenses in 1784.

Tinted lenses were first used in China during the 14th century. Chinese judges wore the lenses to hide their eyes during proceedings.

Around 1750, James Ayscough introduced lenses tinted green and blue to aid in correcting vision problems.

Sam Foster sold the first sunglasses on the Atlantic City boardwalk in 1929. Foster started the Foster Grant Company in 1919.

Eyeglasses have come a long way. A leading fashion designer recently interviewed on the Today show was asked, "what is the most important fashion accessory?" The answer: "eyewear, it is the first thing you notice." Eyewear is a fashion accessory which can create images of sophistication, intelligence, sexiness, wealth, youthfulness, mystery to name a few. Worn by people of all ages, incomes and backgrounds, eyewear has stood the test of time.

New developments are constantly changing the eyewear industry. Technological improvements in materials, design and manufacturing processes keep moving the industry in many directions. Fashion is a driving force in the eyewear industry and, at times, is almost impossible to keep up with. Fashion has many cultural influences. Movies and celebrities can be responsible for a fashion trend overnight. Counter culture fashion can be found in the youth market. Designer names are so numerous in the eyewear business it would be a list that, once compiled, would need to be constantly updated.

The eyewear business is dynamic. Driven by fashion and new developments, the eyewear business is interesting, fun and very profitable. You can participate in this fabulous industry and broaden your horizons while having fun and making money.

Sunglasses

Ultraviolet Light
Light is an energy source which is measured in wave lengths. The wavelengths are calibrated in nanometers (nm) and one nanometer is a billionth of a meter. Visible light, (white light) is the spectrum of 380nm to 780nm. The color red is at the high end of the white light spectrum while violet and blue is at the low end. Violet and blue have shorter wavelengths and are more scattered and is the reason the sky looks blue. Ultra violet (UV) light is invisible and is harmful. UV is short wave length energy from 100nm to 380nm. UVA are 315nm to 380nm and are the closest to visible light. UVA is less harmful than UVB. UVB is responsible for sunburn, skin cancer and various eye diseases. Protection from ultraviolet is very important especially for children.

Most sunglass lenses filter at least 60% of UV light. Special coatings can improve filtration to over 90%. The best UV filtration can be found in polarized lenses. Polarized lenses filter 100% of UV light. People who spend time on the water, snow and at high altitudes need to pay particular attention to the dangers of ultraviolet light. Contact lens wearers must also exercise caution due to exposure of UV light.

Lens Materials
Sunglass lenses are available in several different materials. Generally speaking, the choices are plastic or glass. Plastic lenses are most common and are available in different types of plastics. Acrylic plastic is the most common material and is the lens of choice for fashion and general purpose sunglasses. Poly carbon (PC) lenses are very popular especially in sport application. PC is the material commonly found in safety eyewear. Plastic lenses are light weight, durable and can easily be tinted and treated to provide a variety of performance characteristics. Plastic is the predominant material in prescription lenses.

Glass lenses, once the primary material in all eyewear, is used in a limited number of high end brand name sunglasses. Ray ban, Revo, Serengeti and Maui Jim are a few of the most recognized names which offer glass lenses. Glass is a superior optical material. Tempered for hardness and polished for optimum visual acuity, glass provides the best in optics. Durability against scratching is another feature found in glass lenses. Glass has some characteristics which are less than desirable. The weight of glass lenses may prove to be a negative feature for some. This is a personal preference and does play a roll in not choosing glass even with all the positive features of glass lenses. Difficulty in tinting and treating glass lenses makes it unpopular in many applications.

Tints and Coatings
Lens tints and coatings all play a role in the performance characteristics of a sunglass. Smoke, green and brown tints are the most popular color tints and are generally a matter of preference for the individual consumer. Mirror coatings will further reduce incoming light and again is a preference by some. Mirror coating may come in different colors or more commonly a silver finish. Anti-reflective (AR) coatings help in reducing bounce back as light from behind enters the inside of the lens.

Smoke tinted lenses are the most popular and are recommended for numerous applications, while green lenses are the most color neutral tint. Brown tint or driver lens tint, (a dark amber color), are recommended for driving and provide high contrast. The brown and amber tints act as a filter to blue light which improves contrast between red, green, and yellow. The brown and amber tints also improve vision in overcast and hazy light conditions.

Photochromic Lenses
Photochromic lenses have recently gained popularity in prescription eyewear. Several sunglass brands offer photochromic lenses in non-prescription glasses. The advantage of photochromic lenses is that it allows the wearer to keep their glasses on when going indoors. Photochromic lenses also adjust to different levels of light, getting very dark in bright sun light and mildly dark in overcast light.

Photochromic lenses are available in either glass or plastic. The photochromic characteristics are built into the lens and are a chemical reaction to incoming sunlight. The lenses are also referred to as sunsensors and will not react to normal lighting or sunlight through windows. Other lens performance characteristics are possible utilizing tints and coatings.

Polarize Lenses
Polarize lenses are very popular and are offered by every major sunglass brand. Polarization removes reflective glare off horizontal surfaces and affords the best protection from ultra violet light. Polarization improves vision on the water and is very popular with boaters and fishermen. The ability to see beneath the surface is an advantage when fishing.

Polarize lenses are available in a variety of plastics and glass. Additional performance characteristics are also possible with polarize lenses utilizing tints and mirror finishes. Photochromic lenses can also come with polarization. Polarize lenses are made like a sandwich with the polarizing film between two thin lenses of plastic or glass. Polarize lenses add a considerable cost to the finished sunglass.

Frames
Frames come in a wide variety of materials. The broad categories are metal and plastic. Metal frames can be of low grade materials such as brass or high quality materials such as aluminum, stainless steel or titanium. The better the frame material the better the finish, appearance and durability. Most metal frames are plated to attain the frame color and in some cases decorative painting is used. Metal frames can come in a semi rimless style where the top or more often the bottom of the frame is open and the lens is attached to the frame using a thin filament such as a fishing line or through the use of screws. Rimless frames are also available where the temples and nose bridge are directly attached to the lenses. Optical frames made of metal have a screw in the frame which opens the frame where a lens can be installed. This feature increases the cost of the frame.

Plastic frames also have different degrees of quality. Injection molded plastics are the most common plastic frames in use today. Injection plastic may be of very good quality or of very poor quality. Recycled plastics are used in low cost, low quality eyewear. Common problems with low quality plastics are brittle frames subject to breakage, poor color finishes and uncomfortable fit. High quality injection frames are made of first quality plastics and go through a polishing process which improves the finish. Lenses can generally be removed and replaced in plastic frames. Heating the frame softens it and allows for some expansion and flexibility. Poor quality frames often will brake under the stress required to remove and reinstall a lens. Plastic frames are light weight and can be molded in a wide variety of shapes. Color choices in plastic frames are unlimited. Plastic temples often are treated with decorative elements to add a fashion component to eyewear.

Polycarbon plastic frames are found in sport sunglasses and safety eyewear. The polycarbon material will not shatter or break.

Acetate or Zyl plastics are popular in the optical trade. Zyl is made of layers of plastic material. The layers may be of different colors, patterns or shades of the same color. The layers are fused together in a sheet of material. The frame shape is cut from the sheet and finished and polished by hand. As the material is cut and finished, the frame reveals the different layers. The layers give the frame design and color characteristics. Zyl frames are much more costly than injection molded frames.


Reading Glasses

Introduction
Reading glasses are a solution for a condition called presbyopia. Presbyopia is the term used to describe the condition which is the loss of near vision related to the aging process. As people get older the lens and muscles in the eye looses elasticity and its ability to focus on near objects. This condition eventually affects everyone. The loss of near vision usually begins near the age of 40 years old. Some may experience it sooner while others may discover it later. Reading glasses correct the deficiency with plus magnification. The magnification is called diopters and commonly start at +1.00 and progress by increments of +.25 going up to +4.00 and above. As people grow older the magnification required usually increases. A person who begins with +1.00 at age 40 may need +1.75 at age 45. The need for greater magnification is an individual requirement and there is no uniformity of a particular age requiring a particular diopter.

Self Test
People determine their magnification needs by self testing or through a test administered by an eye care professional. The self test is simply reading small print with a pair of reading glasses on. If the individual has never used reading glasses before then they would begin their test with a +1.00. Holding the reading material at normal reading distance (14” to 16”) away, the print should be in focus. If the printed material needs to be held further away to focus, that would indicate that a stronger pair of reading glasses is necessary. Continue the process increasing the diopter by +.25 each time to find the correct strength. If an individual were unable to find the correct diopter and was having difficulty reading, then a visit to an eye care professional would be recommended.

Frames
Reading glass frames come in a wide array of shapes, colors and styles. Choices of conservative to outrageous, traditional to sophisticated, reading glass frames have it all. Frames come in full size and half size. Half frames are popular especially in higher diopters because it is uncomfortable to look off in the distance with strong plus magnification for most people.

Lenses
Reading glass lenses are plastic in the majority of cases. Lenses are available in bifocal with a small reading area in the lower section of the lens and no magnification in the top section of the lens. Lenses can be tinted and treated for performance the same as sunglasses. Sun readers have been very popular and are available in bifocal and non-bifocal. Computer readers are a relatively new product with special tint and anti-reflective coating to combat computer vision syndrome.