Re: Calculating Add for computer work

On Tue, 29 Jan 2008 13:39:40 -0600, "Mike Tyner" <mtyner@xxxxxxxxxxxxxx> wrote:


"Robert Martellaro" <robopt@xxxxxxxxxx> wrote

True, but a half diopter is a room distance lens, not a computer lens. Or
as Jon
Stewart might say, it's more like a gratuity, and a cheap one at that.

But the doctor wrote +1.00 for 20 inches.

I don't think we know that. The OP said the Add was for reading. You surmised
"To say your "add is +100" doesn't tell us much if we don't know what
distance it's calculated for. I'd guess you held the book about 50 cm".


That suggests the OP is 45 or
less, with considerable accommodation remaining.

Right. He shouldn't need computer glasses.

Even at 53, I use +050 in my distance portion and VDTs are quite legible at
30 inches or so through that. Not "crisp" but not so blurry that I
habitually tilt back.

I have clients who look at the monitor for hours at a time, reporting an
average monitor distance of 24". They need and want crisp.

Even when accommodation is gone, depth-of-field and
tolerance for blur allow a range.

I've found that this varies from one person to the other, probably related to
pupil diameter and maybe changes in the lens. A +2.50 Add client I saw yesterday
could see my monitor comfortably at 25". I didn't expect that- most people
struggle and have to tip their head back, shocked at how much clearer the text
looks when +1.50 is placed over the glasses. Her reaction was the opposite, not
much better with than without. Although she uses her computer a moderate amount
of time, I didn't recommend separate glasses because she was non-symptomatic and
comfortable with the existing quality of vision.

BTW, my office monitor is at 32", and unless I bump the font good and plenty I
see a lot of blur. My home monitor is at 25" and I don't even try to look at it
with my everyday glasses. (Add is +2.25 at 40cm.)


MT >>IMO there's more danger in those 1/2-inch "fashion" temples that
California
outlawed in 1959.


I didn't know that. Most folks don't seem to ever look in their mirrors
anyways.

It interferes enormously looking over your shoulder to back up, and
obliterates the "corner of your eye" vision used for that 18-wheeler
sneaking up in your blind spot.

-MT

Now, if we can only get urban drivers to recognize that an automobile isn't
their living room on wheels!

Robert Martellaro
~~~~~~~~~~~~~~~~~~
Optician/Owner
Roberts Optical
Wauwatosa Wi.
~~~~~~~~~~~~~~~~~~
"Science is a way of trying not to fool yourself."
- Richard Feynman
.

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