Monday, July 28, 2008

Less Magnification or Minification of the Eyes

Also, the flatter aspheric lenses end up positioned closer to the face. This is a major benefit for anyone wearing a strong correction.

Aspheric lenses lessen the magnification of the eye usually seen in strong plus lenses.

For strong farsightedness, aspheric lenses reduce magnification of the eye. The eye at left is seen through an aspheric lens. Through a conventional lens, the eye at right appears larger, even though the lens is the same power.

Strong farsighted lenses have a tendency to enlarge the wearer's eyes, producing an unattractive magnified look. Strong nearsighted lenses do just the opposite: they minify the wearer's eyes so they tend to look small and beady. Positioning a strong correction closer to the eyes lessens this magnification or minification, for a more attractive, natural look.

In minus lenses for nearsighted people, the front surface curves steepen away from the center and toward the lens edge. As a result of this gradual curve change, lenses end up with thinner edges. From an appearance standpoint, the thinnest possible edges for a strong nearsighted lens are produced when the aspheric lens is made of a high-index material.

An even newer type of aspheric lens for strong nearsightedness has aspheric curves on the back side of the lens. This produces the thinnest possible edges for very strong minus prescriptions.

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