Defining the Various Eyeglass Lens Options
When it comes to eyeglass lenses, there is much more than meets the eye. If you think that eyeglass lenses contain a prescription and are shaped to fit within your chosen eyeglass frame, you'd be right because that's the way it's been for years. And while eyeglasses are great at correcting a multitude of vision problems, they offer even more benefits.
Of course, there's a price to be paid for these new and improved benefits, and the more you choose, the more your eyeglasses are going to cost. How do you know which eyeglass lenses are right for you?
Here's A Brief Summary About Different Types Of Eyeglass Lenses
Anti-reflective eyeglass lenses are actually coated with metal oxides that improve vision by reducing glare and reflection. Reflections on the surface of an eyeglass lens can cause ghosting and eye strain. Anti-reflective coatings eliminate these problems and those that are caused by such things as oncoming headlights and fluorescent lighting reflecting off computer screens, two big sources of strain. These coatings also make glasses look better as the surface won't have that noticeable mirror effect.
High index eyeglass lenses eliminate the need for that legendary 'soda bottle look'. The rule of thumb has always been the stronger the eyeglass prescription, the thicker the eyeglass lens in order to accommodate the right amount of light bending. High index lenses changed that and their development enabled eyeglass frame manufacturers to begin creating extremely thin or rimless frames.
High index lenses made out of plastic are very light since less material is used in the construction of the lenses. These lenses can also be made from glass however, because glass is heavier, the end result won't be a lighter feeling lens. There is a range of high index lenses and understanding higher vs. lower index is a bit complicated, so it is best to let your eye doctor explain the differences. In general, higher indexes cost more and should be thinner. These eyeglass lenses also benefit from the addition of an anti-reflective coating which blocks less light.
Photochromatic lenses change from regular clear lenses into dark-colored lenses, similar to that on sunglasses, when they are exposed to sunlight. The convenience of having '2 pair of eyeglasses in 1' is less expensive. Transitions lenses are the most familiar of this type of lens and they are available in practically every prescription and refractive index.
They offer full ultraviolet protection, too. The secret behind the color changing capability is silver halide which is mixed right into the lens when it's being created. In the early days, thicker parts of the lens resulted in darker areas, but this has been virtually eliminated with the introduction of polycarbonate and high-index lenses. Besides Transitions, many other companies offer some variation of the photochromatic lens. Corning, the original developer, has several styles including Thin & Dark and SunSensors, as well as the originals, PhotoGray and PhotoBrown.
Progressive lenses offer state-of-the-art vision correcting capabilities. Most often prescribed to treat presbyopia, these lenses eliminate the need for the telltale horizontal lines that separates the different prescriptions. That's because of the unique mapping technology that positions the different prescriptions onto different areas of each lens.
Besides near distance and far distance prescription positioning, there can be an area in the center for intermediate vision. This area helps with the transition from near to far and vice versa and accomplishes this using a number of different curves that have been designed to blend together. A better understanding to this progressive technology has made custom-designing progressive lenses to fit a person's lifestyle much easier. And it has also helped manufacturers figure out how to fit so much capability into smaller eyeglass frames so that those with presbyopia, who tend to be older, can have eyeglasses with a more contemporary look. Expect an adaptation period and before ordering make sure you can exchange the lenses should you not be able to adjust.
Multifocal lenses are yesterday's bifocals and trifocals. As the name implies, multifocals have multiple focusing abilities and are commonly prescribed for activities such as reading and computer work. These lenses still have the telltale lines or curves that delineate the different prescriptions which is why more people are making the switch to progressive lenses. Bifocals offer near vision and distance vision correction, while trifocals include near, far and intermediate correction. Multifocal lenses are often prescribed when needed for specific job functions. As such, they're not generally designed to be worn daily - only when performing the specific task for which they were designed.
Polarized lenses block out damaging ultraviolet rays and enhance color, making these eyeglass lenses a good choice when driving. Colors are crisp and defined because they're not obstructed by the sun. Polarized lenses help reduce glare and haze, making visibility much better.
Polycarbonate lenses are perfect when you need eyeglass lenses that are durable and offer built-in protection from damaging ultraviolet rays. Even though they are great at resisting impact, these eyeglass lenses are amazingly thin and weigh less that regular plastic lenses. Polycarbonate lenses get their strength from the manufacturing process which helps make the lens more flexible and less brittle. The material is not scratch-resistant however, and most manufacturers apply a coating to protect the lenses from this type of damage. Many parents choose this type of lens for their children as do those who participate in sports.
Tinted lenses are popular and are preferred by many for the fashion statement these eyeglass lenses make. Others choose tinted lenses to do double-duty as sunglasses. Once a tint is in place, it's there all the time, which is one way these lenses differ from photochromatic lenses. The tint can be solid or it can gradate from darker to light or vice versa. Tinting lenses involves submerging the eyeglass lenses into warm water that's been colored. In a process similar to dying Easter eggs, the longer the lenses remain in the colored water, the more enhanced the tint becomes. A tint can also be applied as a lens top coating.