I Need Formula for Lens Tilt

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midwest_46@yahoo.com - 19 Sep 2007 02:54 GMT

Hi. I recently found Martin's formula for lens tilt. This formula
shows the power of a lens whose optical center is at the center of the
eye.

For example, if a lens is -4.00 diopters and if the optical center is
at the center of the eye, then the formula will tell you how much
actual power the lens has, given the pantoscopic tilt of the lens.

What I need is a formula that will tell me the actual power of a lens
whose optical center is BELOW the center of the eye.

In other words, given the power of the lens (in diopters) and the
pantoscopic tilt and the distance between the oc and the center of the
eye, what is the actual power of the lens?
I need a formula that computes actual power if the oc is BELOW the
center of the eye.

Can someone give me this formula? Or give me a website which has the
formula?

Thanks a lot.

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lena102938 - 19 Sep 2007 02:56 GMT

On Sep 18, 8:54 pm, midwest...@yahoo.com wrote:

> Hi. I recently found Martin's formula for lens tilt. This formula
> shows the power of a lens whose optical center is at the center of the
[quoted text clipped - 17 lines]
>
> Thanks a lot.

www.i-see.com
very helpful.

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Neil Brooks - 19 Sep 2007 03:08 GMT

Sorry. Rishi Giovanni Gatti (Zetsu), Lena102938, and Otis Brown are
trolls who haunt s.m.v.

Rishi has published, and is trying to sell worthless books.

Otis is pathologically dishonest and actually hurts people.
Following his advice can induce double vision in those
not working closely with an eye doctor.

Lena102938 uses anti-eye doctor rhetoric as a substitute for ANY
actual information. It seems she now has to wear glasses and has
developed a pathological (and ILLOGICAL) resentment toward the
industry that "foisted these glasses upon her."

You'd do well to ignore them and wait for responses from the
caring, compassionate eye doctors who DO also participate in this site.

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Robert - 19 Sep 2007 14:28 GMT

>Hi. I recently found Martin's formula for lens tilt. This formula
>shows the power of a lens whose optical center is at the center of the
[quoted text clipped - 17 lines]
>
>Thanks a lot.

Martin's formula for tilt for those who don't have it.

S1 = S[1 + (sin2 a) / (2n)]
C1 = S1(tan2 a)

S1 = new spherical power
S = original sphere power
a = degrees of tilt
n = index of refraction
C1 = induced cylinder

Tilting the lens (vertically) increase the power, and induces cylinder with a
180 axis, the sign equal to the sphere. The errors result from not having the
optical axis of the lens passing through the eye's center of rotation, and can
be corrected by lowering the OC below the pupil .5mm for every degree of panto-
ie, if there is 10 degrees of panto then lower (below the pupil) the OC 5mm. So,
if the panto is zero, and the OC is 5 below (the pupil), make "a" = 10 to get
the power of the lens.

http://www.optiboard.com/forums/showthread.php?t=9278

Tilt and wrap are discussed. There are additional threads worth reading- just
poke around awhile or use the search function.

http://www.optiboard.com/forums/attachment.php?attachmentid=2519&d=1160291047

A nice tilt compensation calculator.

Hope this helps

Robert Martellaro
~~~~~~~~~~~~~~~~~~
Optician/Owner
Roberts Optical
Wauwatosa, Wi.
~~~~~~~~~~~~~~~~~~
"Science is a way of trying not to fool yourself."
- Richard Feynman

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