At 1:49 AM +0000 12/13/03, olympus-digest wrote:
>Date: Fri, 12 Dec 2003 12:35:18 -0500
>From: "Lama-Jim L'Hommedieu" <lamadoo@xxxxxxxx>
>Subject: Re: [OM] Dioptric Correction
>
>I told my optometrist I wanted to pay him for second examination, to come up
>with the exact prescription needed for a distance of 1 meter.
>
>He said that with all of the technology available to him, he had no way to
>test at one meter. He could test at infinity and that's it.
Find a new optometrist. Or better, an opthalmologist.
I had no difficulty getting a prescription tuned to any desired distance.
Specifically, I got one tuned to 18 inches (46 cm) for use with the computer
and other close work, and my wife got one tuned to 24 inches (61 cm) for
playing the piano. We have different opthalmologists, and neither had the
slightest difficulty. They have a test fixture with a sliding holder for the
eye chart. They set the eye chart at the desired distance, and go to work.
The only problem I had was that the normal practice is to find the prescription
for each eye independently of the other, and this almost always works OK, but
failed for me (perhaps because my target distance was so close). The problem
was that the eyes fought with one another, trying to find a focus acceptable to
both, but the two eyes were too far apart in implied target distance. So, the
opthalmologist did it over, this time doing a final adjustment with both eyes
at once, and that worked. I am wearing the glasses as I type these words.
The opthalmologists called these special prescriptions "computer glasses".
Aside from the obvious need to see despite aging eyes, I had another reason to
want computer glasses -- safety. When doing the close work, generally working
on some kind of hardware, I found myself bringing my eye to within three or
four inches of what I was working on, and worried that I would eventually poke
myself in the eye with a sharp tool, or have something spring out and get me in
the eye, etc. The glasses both allow me to be farther away, and physically
stop such things from getting to the eye.
In the US, opticians can only make glasses, optometrist can also fit glasses,
but opthalmologists are licenced medical doctors and can everything, including
eye surgery.
If you are older than 35, you should have an opthalmologist examine your eyes
at least once every three years, need it or not, because some of the important
eye diseases give the patient no warning symptoms before irreversible blindness
sets in, but a doctor can pick these diseases up far before the patient can
tell. Optometrists won't do, it must be a opthalmologist.
>I decided to make the transition to AF immediately, before I'm too old to want
>to learn something new. Scary, but it's better than being dead already.
The opthalmologist plus new glasses is far cheaper, and doesn't force one to
learn the ins and outs of a glass-equipped computer, a wunderbrick. Nor is
autofocus such a panacea.
Olympus should know the apparent distance they designed the viewfinders to.
I've heard one meter and two meters, which are plausible, but don't know if
either is correct. One can test this by looking alternately through the
viewfinder (at the split prism) and a wall, and move until switching between
the two causes no shift in the eye's focus (which one can feel).
Joe Gwinn
>
>From: "Mike" <watershed@xxxxxxxxxxxxxxx>
> > I asked my optometrist for the correct prescription for this
> > distance. My old glasses would not work as
> > you suggest as they are for distance vision.
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