lens for glasses- sight impaired

[frwbeach]

  I am sight impaired  20-50  and usually get the polycarb lenses I recently was told   that reg glass lenses are much clearer and  she could see clearer with them . Is this a fact or fiction??  Getting new glasses and any improvement would help. Thank you

[JohnHaganMD]

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[SoftwareDeveloper]

Crown glass does have better optics, but with a low prescription like what you would have its likely most people wouldn't notice the difference. Most  people tend to avoid glass these days due to the risk of breakage, the extra weight and because other options are often cheaper. It does tend to superior optics due to things like a higher abbe number as this explains:

http://www.allaboutvision.com/lenses/how-to-choose.htm
"The Abbe value (or Abbe number) of a lens material is an objective measure of how widely the lens disperses different wavelengths of light as light passes through it. Lens materials with a low Abbe value have high dispersion, which can cause noticeable chromatic aberration — an optical error visible as colored halos around objects, especially lights.

When present, chromatic aberration is most noticeable when looking through the periphery of eyeglass lenses. It is least noticeable when looking directly through the central optical zone of the lenses.

Abbe values of eyeglass lens materials range from a high of 59 (crown glass) to a low of 30 (polycarbonate). The lower the Abbe number, the more likely the lens material is to cause chromatic aberration."

There are other options like CR39 that has a higher abbe than polycarb.

[JohnHaganMD]

Sorry "glass" lens.

[JohnHaganMD]

Fiction. I can't think of any reason at all to get glasses lens.

JCH MD