Re: K values and PRK/Lasik?


William Stacy wrote:
> OK I'm a bit dizzy from looking at those numbers, but from what I can
> make out, spherical aberration seems to be lower in magnitude than both
> coma and trefoil, and in pupils below 6 mm all 5 types seem to be
> insignificant (the means are = to or only slightly larger than the
> standard deviations, and are pretty close to zero. Of course we know
> that all these aberrations are miniscule when compared to chromatic
> aberration, regular astigmatism, and ordinary defocus, except in
> disaster corneas. Now it is true that some or all of the 3rd order
> aberrations will get larger with LASIK, but I can't see spherical
> aberration as getting larger or any more significant than the others,
> unless you've got other references to throw my way (please do). My guess
> is that irregular astigmatism and distortion will win out in importance
> in problem corneas.
>
> You gotta love those Zernike Polynomials!
>
> w.stacy, o.d.
>
> Dr. Leukoma wrote:
>
> >In fact, I'll give you the link to a table such information showing the
> >first five orders of Zernicke aberrations as a function of three
> >different pupil sizes. The data is from "normal" subjects:
> >http://arapaho.nsuok.edu/~salmonto/Zernike%20norms.xls
> >(Data tables for presentation by Salmon & van de Pol at the American
> >Academy of Optometry annual meeting, December 9, 2004, Tampa, Florida.)
> >
> >Please note that spherical aberration is prominent and increases with
> >increasing pupil size.
> >
> >DrG
> >
I didn't intend to make you dizzy. I can see that you might want a
primer, and I found an excellent one. It can be found here:
http://www.opt.pacificu.edu/ce/catalog/10260-RS/WavefrontSalmon.html

By the way, the rest of the article supported by the spread*** data
can be found here:
http://arapaho.nsuok.edu/~salmonto/Zernike%20norms.pdf

And, by the way, I did not invent Zernicke polynomials, and I didn't
say I "loved" them, but that is the modern language of optics....until
now. Get ready for Fourier.

DrG

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