It's simple, John. Certain people need help focusing at certain distances.
The traditional bifocal prescription involves different corrections for
distance (infinity) and reading (12" away) use. Guess what...unless you sit
unusually close to your screen, neither one of those is the right strength
for working on a computer! Or a typewriter, or even a desk, truth be known.
So, they came out with the "computer prescription," which is the right
correction for an object (monitor) that's just about at arm's length. Works
well for people who work at desks, all day long... One other benefit is the
wide field of vision. No matter how good a pair of bifocals or
progressives, the relevant part is *tiny* compared to a pair of single
vision glasses. I don't yet wear bifocals, so I can only imagine what it's
like. I have a 24" monitor, and can't imagine peeking at it through
something as tiny as a bifocal.
There's one other benefit to it, the way we buy glasses. Single vision
glasses are so cheap online, that we can have specialized pairs for
specialized tasks. If I had to pay $400 for a pair used only with my
computer, I would complain...an extra $8-13 doesn't hurt nearly so much.
-- Chuck Knight
On Sat, Mar 21, 2009 at 6:13 PM, John Szlachta <[email protected]> wrote:
>
> What's the story with computer lenses? Is this some kind of marketing
> ploy? Why would you wear single vision lenses in anything other than
> your full correction? Unless I'm missing that we're talking about
> progressive lenses here.
>
> iPhone
>
> On Mar 21, 2009, at 8:37 PM, Firewalker <[email protected]>
> wrote:
>
> >
> >> I just ordered 1 more pair tonight for computer use.
> >>
> >> My normal perscription is
> >>
> >> OD -3.50 -1.50 X 24
> >> OS -4.50 - 1.50 X 165 add + 2.25
> >>
> >> I ordered for computer
> >>
> >> OD -2.50 -1.50 X 24
> >> OS -3.50 -1.50 X 165
> >>
> >> Is that correct?
> >
> > If that ADD +2.25 is for both eyes, and not just for the left eye as
> > shown, then yes, that is correct.
> >
> > For the record, computer (or intermediate) glasses would have approx.
> > half of the ADD power added to the original SPHERE value. When it's an
> > odd number like +2.25, then you'd add either +1.00 or +1.25 to the
> > SPHERE value.
> > Just remember, if your original SPHERE is a negative (myopia), then
> > adding power to it would make the SPHERE go the opposite direction.
> > (-3.50 ADD +1.00 = -2.50).
> >
> > -=# Firewalker #=-
> > >
>
> >
>
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