Rich said:
I got a pair of drugstore bifocals once, and I think the bi-parts were
misaligned with my lines of sight - I got terrible eyestrain headaches
after about 15 minutes. Now I have a 1.75 or so for the computer and a
2.0 for the crossword puzzle. I was kind of bothered when the other
day I happened to look at my TV, which is at the foot of my bed, with
my computer glasses, and it was crystal-clear. Damn! I don't want my
eyes to get even lazier! )-;
Cheers!
Rich
Don't worry Rich, the lenses won't make your eyes lazy.
General reading glasses' considerations:
They may bug you if the lenses' centers aren't spaced the same as
your eyes are when converged on your work. If the lens is off-center
with your pupil, prismatic distortion results, which displaces objects
laterally from the position expected/predicted by the focusing effort
now needed to focus on them. (The apparent displacement is also likely
different for each eye.) Vertical displacement is disorienting, even
nauseating.
The result is that your extra-ocular muscles clash from the
conflicting cues--e.g. simultaneously trying to _converge_ to match the
focusing effort, and _diverge_ to line up the images from the two eyes.
Fighting each other is tiring, producing a headache ("eyestrain").
These difficulties can be avoided or fixed by
1) just practicing and getting used to the lenses, if the adjustment
isn't too severe,
2) using weaker lenses and longer working distances,
3) getting lenses with the correct spacing (IP / "interpupillary
distance"), or
4) using an optical aid with built-in prismatic correction, like the
OptiVisor-style head-mounted magnifier (very nice, and not expensive).
The latter, ideally, allows *you* to look straight ahead and focus at
'infinity' while the device focuses and redirects your line-of-sight to
the workpiece, thus avoiding any strain at all.
The distortions and problems increase rapidly with stronger lenses,
but, being ideally myopic, t'ain't a problem for me--I can usually get
by with no lenses at all :-\
If you're pre-presbyopic, e.g. <40 years old, you can use reading
glasses to train yourself to reduce myopia by a diopter or so.
Cheers,
James Arthur