Short and long sight

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?

 

Very common.

 

A bit of light reading for the two of you....

http://en.wikipedia.org/wiki/Presbyopia

She should probably get her eyes checked, just to rule out any other
possible cause, but ... the timing's right.

 

Very common. If I remember correctly, about half of all people develop
this in their mid-forties. The rest get it later. It's part of the
aging process. I wore reading glasses over contacts for many years.

 

I get that. My question is - why does she need reading glasses only
when she is wearing contact lens? Why doesn't she need reading glasses
when she isn't wearing contact lenses?

Defense against what?

Could you elaborate?

I also am short sighted. I have a power of 0.75 in both my eyes.
I wear glasses for driving & watching TV/Movies.
I also feel I may need reading glasses very soon. My fine print
reading has deteriorated just a bit - I can reads books & newspapers
just fine, but very fine print has started getting a little bit
difficult. I am also around the same age as her.

She visited the optician (not doctor) and got reading glasses. When she
is at home & not wearing contact lenses, she doesn't need these at all.
Only when she is out wearing contacts, she carries these in her purse
if needs to read something.

What's that?

Ok. We will visit the eye doctor soon.

 

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
~~~~~~~~~~~~~~~~~~
Roberts Optical Ltd.
Wauwatosa Wi.
www.roberts-optical.com
~~~~~~~~~~~~~~~~~~
"Science is a way of trying not to fool yourself."
- Richard Feynman