I'm not a doctor, but . . . to my understanding . . . this is because of
"vertex distances."

The vertex distance is the distance between the front surface of /your/
cornea and the back surface of the corrective lens.  When a lens for
/nearsightedness/ (what you have) is moved /closer/ to the eye, it becomes
"stronger;" therefore, when you fit a contact lens, instead of glasses, you
need a lower power lens.

If you were farsighted, the power of the contact lenses would be /higher/ by
roughly the same amount.

Does that make sense?

Neil

In this case, it isn't because of vertex distance. It's because the tears
between the RGP lens and your eye create another lens with measurable power;
on the right eye it's roughly -1.00 horizontally and -2.00 vertically.

Assuming a normal fitting relationship between the lens and eye, the K
readings for your right eye can be calculated at roughly 44.75 / 45.75.

-MT

Victor,

Good question. Vertex compensation would only account for .25DS on the right
only. Is this an Orthokeratology fitting? Is the left power cut for near
(monovision)? Ultimately you should consult with the doctor for this and other
questions pertaining to your eyecare.

Hope this helps

Robert Martellaro
~~~~~~~~~~~~~~~~~~
Optician/Owner
Roberts Optical
robopt@execpc.com
~~~~~~~~~~~~~~~~~~
"Science is a way of trying not to fool yourself."
 - Richard Feynman