Previous to the last few years, the only materials available to use for lenses were glass and a hard resin called CR-39. But recently, high index lenses have become available. High index materials are named because they have a higher index of light refraction. Basically, they can do the same job that glass or CR-39 does, but high index lenses are much thinner and lighter. With high index lenses, you can avoid having "soda bottle" lenses.
When speaking about high index lenses, you may hear many unfamiliar numbers and terms. Here are a few things to remember.
The first and still most popular high index plastic is polycarbonate. Polycarbonate was originally developed for fighter jet cockpits. It is very strong, very light, and resistant to scratches and impact. Most sports lenses are made of polycarbonate.
High index lenses, such as 1.66, 1.74, and 1.9, are much thinner than regular glass or plastic. Talk with your doctor to decide which high index lens is right for you.
For many people, different lenses are needed for seeing at different distances. Bifocal lenses allow the wearer to look through two areas of the lens. One area focuses on distant objects. The other is used for reading. A little-known fact is that bifocals were invented by Benjamin Franklin, and his style of bifocals are still available today.
Most of the time the "reading" area is smaller, shaped like a sideways "D", and found in the lower hemisphere of the lens. These bifocals are called line bifocals or flat-tops. If you are focusing on distant objects, you look through the top half of the lenses. To read a book, magazine, or newspaper, you look through the "reading" area. The Franklin style lenses are less common, and are split horizontally down the middle of each lens. One thing that is difficult about using bifocals is dealing with the line between the two vision areas. Fortunately, recent technologies have developed a new type of lens, called the no-line, or progressive lens.
Bifocals allow the wearer to read through one area of the lens, and to focus on distant objects through another area of the lens. As the eyes age, though, a stronger prescription is needed to read. This would be fine, but the stronger prescription that allows for reading makes it difficult to focus on objects at intermediate distances, such as grocery items on a shelf or your speedometer. Thus, trifocals are necessary for a third prescription for intermediate focusing.
Trifocals, also known as line trifocals, feature three areas of focusing power, each separated from the other by a distinct line. The three windows allow for focusing on distant objects, intermediately distanced objects, and for reading. The downside of trifocals is dealing with the lines between the different focusing powers. Fortunately, recent advances in technology have led to developments in no-line, or progressive lenses.
One of the main problems with bifocal and trifocal lenses is the problem of eye fatigue. It is difficult to switch from one focusing power to another. It can make your eyes tired, and it can even lead to a headache, sore neck and sore back.
A recent variation of bifocals and trifocals are called no-line lenses or progressive lenses. No-lines provide a smooth transition from focusing on nearby to focusing on distant objects because they do not have a distinct line, which separates the focusing powers. Instead, a gradual change in power allows the wearer to focus on objects at all distances. Distant objects are viewed through the upper portion of the lens, while near objects are viewed through the middle or lower portion of the lens.
Each passing day, computer use is on the increase. But our eyes aren’t comfortable with this trend. CVS (Computer Vision Syndrome) is the result of your eyes’ constant effort to focus on a computer screen. As a result extended computer viewing can lead to these common symptoms of CVS:• Eyestrain and fatigue
Computer lenses are designed to help you code with all of your unique and changing needs. They even allow you to work for extended time in from of a computer, letting your eyes accommodate to seeing close up or nearby objects, so you can enjoy a higher level of viewing comfort with excellent performance that computer lenses offer. Ask your doctor about the options available to you to improve your computer vision comfort.
If you have hard resin lenses (CR-39), you should consider getting a scratch resistant coating. Resins and plastics are more susceptible to scratches than glass. Scratches damage the cosmetic look of the lenses as well as their performance. With a scratch resistant coating, you don't have to worry so much about minor scratches on your lenses.
Another advantage of scratch resistant coatings is that most coatings come with a one-year warranty. They are a great investment to prevent minor scratches. However, it is important to remember that scratch resistant does not mean scratch-proof. All lenses are susceptible to scratches. However, an extra tough scratch resistant coating is now available called TD2 (tough, durable, 2-sided). It gives you more scratch resistance and a 2 year warranty on you lenses, a must for children and anyone who is active or needs that extra protection.
Your glasses don't have to be an eyesore to those around you. Eyeglasses can be a stylish accessory, a part of your personality, or a way for you to be different. There are a variety of frames to choose from, but you may not know that there are a variety of ways to improve the appearance of the lenses, too. Cosmetic tints are now available. These tints offer a variety of colors and shades. You can choose light blue or any color under the rainbow. Some lenses are clear at the bottom and gradually get more colored towards the top of the lenses. There are many ways to adjust your lenses to whatever style suits your personality. Some tints are also functional.
Recently there has been much attention on a condition called Computer Vision Syndrome, or CVS. A special tint for your glasses can reduce eyestrain associated with CVS. There are many other tints to choose from, as well.
If you've ever felt frustrated at needing prescription glasses and prescription sunglasses to accommodate an outdoor lifestyle, you should consider photochromic lenses. Photochromic lenses darken when exposed to UV rays. The change is caused by photochromic molecules that are found throughout the lens or in a coating on the front of the lens. When the wearer goes outside, the lenses darken or tint. When the wearer goes back inside, the glasses become clear. Photochromic offer 100% UV protection are scratch resistant and are available in brown or gray tints and a wide range of prescriptions.
There are a variety of photochromic options available. Depending on what you choose, you can customize the lenses to your needs. Some lenses darken only in direct sunlight, while others darken in little or no direct light. Some are designed to darken while you're in the car to reduce road glare while you're driving. You can even choose the color of the tint. Ask your doctor what options are available.
Glare from wet roads, light reflecting off other vehicles, and glare from your own windshield can be annoying and dangerous. To eliminate this glare, we offer polarized lenses. Polarized lenses eliminate almost all glare, reducing eye strain and increasing visibility. Polarized lenses are the most effective way to reduce glare.
Most glare comes from horizontal surfaces, so the light is "horizontally polarized." Polarized lenses feature vertically-oriented "polarizers." These polarizers block the horizontally-polarized light. The result is a glare-reduced view of the world. Polarized lenses can make a world of difference for any outdoor enthusiast. Fisherman can eliminate the bright reflections from the water and actually see into the water more easily than with any other sunglasses, golfers can see the green easier, and joggers and bikers can enjoy reduced glare from the road. In addition, drivers can enjoy the safety and comfort that polarized lenses provide while driving during our bight sunny days.
Ordinary Glass compared to Anti-Reflective
Normal lenses often create glare, reflections, and "ghost images." Now that can be eliminated with an anti-reflective coating.
What we see is a result of light being sensed by our eyes. With normal glasses, much of the light reflects off the lenses. This produces glare. It also reduces the wearer's visual acuity. In other words, the light reflections are a cosmetic and visual problem.
Anti-reflective coatings increase light transmission through the lenses to 99.5 percent. It makes it easier to see and easier for others to see you. These coatings are especially useful for those viewing computer screens and driving at night.