May 8th, 2010 An Introduction to Trifocal Sunglasses
Trifocal and bifocal sunglasses are both kinds of multi-focal sunglasses, which is a combination of both sunglasses and multi-focal eyeglasses. However, trifocal sunglasses are an extension of bifocal ones, since bifocal sunglasses have two focus points while trifocals have three, which are the three regions for far, intermediate and near vision, respectively. The region in the bottom of the lens is basically on line pharmacies for the near vision like reading, and the region in the top is usually fo buying drugs r the far vision like scenery viewing.
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An Introduction to Trifocal Sunglasses
