On Sun, 15 May 2011 11:09:32 +0530, Glen <(E-Mail Removed)> wrote:
>My wife is 42. She had short sight from school times & wears
>contacts (power is around -3 & -4). For the last couple of years
>she has developed long sight which happens only when she is
>wearing her contacts.
>When she isn't wearing contacts, she can read books fine. But when
>she wears he contacts, she needs reading glasses for reading books.
>Is this common?
It's not unusual. The accommodative requirements of a spectacle-corrected myope
are less than a CL-corrected myope, or an emmetrope, and is explained by the
effect spectacle lenses have on the vergence of light rays from a near object.
Spectacle-corrected myopes converge less at near also, due to the base in prism
induced as the eyes converge behind a minus lens.
Robert Martellaro
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Roberts Optical Ltd.
Wauwatosa Wi.
www.roberts-optical.com
~~~~~~~~~~~~~~~~~~
"Science is a way of trying not to fool yourself."
- Richard Feynman