Sun-glasses are made in a variety of colors and shades. In most cases, it is the customer who picks the color or shade. So far, there is no special color which is generally claimed, by the public or the optical profession, to be the best color. In fact, I saw a government booklet, a few years ago, which stated that, after some years of research, they were still unable to determine which color would be best.
Colored glasses, sold in stores, have no optical power, they do not change or affect the focus. They are neutral glasses. The same is true of goggles, which have no color. Goggles protect the eyes from dust or cinders. many goggle-wearers also would do better if they wore focus-glasses.[*] many cases, oculists and optometrists prescribe a shade of color in the focus-glasses. Color can be added to focus and focus can be added to colored glasses.
Colored glasses or goggles are made with flat lenses and with curved lenses. Most colored glasses have a plus 6.00 curvature on the outside surface of the lenses and a minus 6.00 curvature on the inside surface. Some colored glasses and goggles have as high as a plus 10.00 curvature on the outside and a minus 10.00 on the inside.
Colored glasses are popular. Plus focus-glasses are unwelcome -- this is because the benefits of colored glasses are apparent and visible, while the benefits of plus focus-glasses, in most cases, are hidden and invisible.
†See "Color vs. Focus in Glasses"
*See "Dust and Focus"
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