Eyeglasses
Eyeglass frame materials
Different eyeglass frame materials greatly expand your options for a new look. While shopping for new eyeglasses or sunglasses, ask your optician for advice about variety in colors, durability, lightness, favorite brands, hypoallergenic materials, uniqueness and price.In fact, finding eyeglasses with the qualities that are most important to you could be as simple as choosing the right frame material, because each type has its own unique strengths.
Plastic frames
If you want the colors of the rainbow, then zyl (zylonite, or cellulose acetate) is your material. Zyl is a very cost-effective and creative option for eyewear and is extremely lightweight. Particularly popular right now are laminated zyl frames that have layered colors. Look for light colors on the interior sides, which can make your eyewear “disappear” from your visual field when you wear them. An all-black frame, on the other hand, is visible at all times on both interior and exterior sides.
Metal frames
Monel — a mixture of any of a broad range of metals — is the most widely used material in the manufacture of eyeglass frames. Its malleability and corrosion resistance are pluses.Still, it is not 100 percent corrosion-resistant: for some people, monel can react with their skin chemistry. But this is preventable if the right kind of plating, such as palladium or other nickel-free options, is used.Many frame manufacturers offer titanium and beta-titanium styles these days; titanium is a silver-gray metal that’s lightweight, durable, strong and corrosion-resistant. It has been used for everything from the Gemini and Apollo space capsules to medical implants such as heart valves.Titanium eyewear can be produced in a variety of colors for a clean, modern look with a hint of color. And they’re hypoallergenic.Some titanium farmes are made from an alloy that is a combination of titanium and other metals, such as nickel or copper. In general, titanium alloy frames cost less than 100 percent titanium frames.
Bifocals
Bifocals are eyeglasses with two distinct optical powers. Bifocals are most commonly prescribed to people with presbyopia who also require a correction formyopia, hyperopia, and/or astigmatism.
Problems with bifocals glasses.
Bifocals can cause headaches and even dizziness in some users. Acclimation to the small field of view offered by the reading segment of bifocals can take some time, as the user learns to move either the head or the reading material rather than the eyes. Computer monitors are generally placed directly in front of users and can lead to muscle fatigue due to the unusual straight and constant movement of the head. This trouble is mitigated by the use of trifocal lenses or by the use of monofocal lenses for computer user.In an interesting legal case reported in the UK in 1969, plaintiff’s ability to use bifocals was impaired by accident.