Millions of Americans require eyeglasses in order to help them see properly. Whether a person is nearsighted, farsighted, or is affected by astigmatism, corrective eyewear can accommodate a person’s vision. The eye doctor runs a series of tests to determine the exact prescription for the glasses, and then assigns the person a series of numbers. These numbers determine what kind of lenses the recipient will need in order to see more clearly. The type of lens itself will also vary depending on the patient’s individual eye-related needs. Another important element that must be considered is the actual measurement of the frames of the glasses. The eye doctor will measure a frame size and include it as part of the prescription as well.
The frame size is the distance between the two pupils, or center of the eyes, and tells eyeglass makers where to place the center focal point of the lenses. If the frame size is off, the person’s vision will not be correct. Everyone is different, and every pair of spectacles is unique to the wearer, so this measurement is very important to the prescription procedure. Each pair of glass lenses is different in shape, style, and in thickness as well.
Glass lenses can be quite heavy, can also be dangerous, and since they are not used often, are relatively expensive. Positive characteristics are, they cause the least distortion of vision and are the most scratch-resistant. However, on the down side, glass lenses block the least amount of ultraviolet light when compared to other lens materials. The most common type of glass used today is Crown glass.
Glass High-Index lenses have become quite popular over recent years. They offer the same intense prescription, but with a much thinner lens so they don’t look as bulky or weigh as heavy on a person’s face. Another thin type of lens is called an aspheric lens. This type of lens is also very thin and they have flatter curves so they look much more appealing on the wearer.
For older eyeglass wearers, there is now something called progressive lenses, which come in a multitude of styles including glass lenses. These are much like bifocals, except there is no visible line there, so they look seamless like regular eyeglasses. These are also referred to as “no-line bifocals.” They are multifocal lenses, so the person can see from all distances under just about any circumstance. Another great lens is the photochromatic lens. These lenses are a hit with the active, on the go group of people who want flexibility in their lenses. Photochromatic lenses change color and get darker with the sunlight, virtually turning them into prescription sunglasses. When the person returns to normal or interior light, the glasses return to their clear, normal state.
Some people may not need prescription glasses at all. A lot of people in their older age may simply need something to use while reading. Non-prescription reading glasses can be found at a number of retail stores. They are not expensive, and can be purchased without a needed prescription from an eye doctor. They come in all colors, shapes, and sizes, and are a great help to those who just need a little bit of assistance when they read. In addition to the lenses mentioned here, there are polycarbonate lenses, lenses with an anti-glare solution added to them, and wave-front lenses, which is brand new technology. No matter what kind of frames or eyeglasses someone uses, there are plenty of possibilities to help people see clearly.