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robin668 Offline



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27.03.2014 06:49
Choice of lenses antworten

Lenses are used directly to optical tools of correction of sight in one eye, choose what kind of Cheap Oakleys Radar Sunglasses Discount lenses will directly affect the optical results.
Should choose a high refractive index in patients with high myopia and hyperopia n=1.70, 1.80 or 1.90 lens (this refers to glasses. Resin lenses currently Supreme refraction rate is 1.74), to reduced lenses of thickness, and should not be purchase discoloration lenses; children Yi purchase optical resin lenses, to guarantee wearing of security; general myopia patients Yi enjoy slightly red of optical red tablets or slightly blue purple of optical can Division tablets, to guarantee blocking most UV on people eye of against; water Shang job who selection polarization King tablets. To increase light transmission rate, improve the clarity to see, plus film lens is optional.
Bifocal and Multifocal lenses are middle-aged and elderly consumers choose the gradient of the lens, which is characterized by a pair of glasses to see close to see. However, bifocal lenses depending on the existing object jump, brings discomfort and inconvenience to the wearer and gradient Multifocal Lens is through the progressive principle of continuous change the focal length of the Cheap Tiffany and Co Necklace Jewelry Outlet lens to achieve the purpose of both far and near, so make the wearer feel very comfortable.
When in the purchase of optical resin glasses, a distinction should be made of a different material resin lens, the material is a thermoplastic, inexpensive but brittle, is low-level sunglasses and reading glasses. CR-39 is the most commonly used optical resin lens, refractive to 1.499, compared with ordinary glass is low, compared to the same degree and diameter of the lens, its thickness thicker than ordinary glass.
There is also something called PC resin lens, has a very great impact resistance, used hammers to strike does not break, but its biggest drawback is that the surface is very easy to clean.
Main has 1.56 refractive index greater than 1.499 single vision refraction and 1.60, 1.70 high index lenses, their prices higher, the biggest feature of optical resin glasses are light weight so it can give consumers especially the highly refractive patients Fake oakleys frogskins sunglasses cheap for sale wearing comfort, but the biggest drawback is the surface easy to clean hair, less durable.

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