please advise about PD, etc.

[ellen]

I am housebound and thus unable to go out and get a new eye exam
without great difficulty. I need a new pair of glasses because, while
I used to be able to read up close with no strain wearing my usual
glasses (-3.0 in both eyes), I now find that I need to push them
further and further down my nose in order to be comfortable when
reading. I'm running out of nose length! My near vision is still very
good, and I don't need the typical sort of reading glasses. I would
just like to have a slightly weaker pair of glasses for when I read or
use the computer.

Here are my questions:

Approximately how much weaker would the prescription have to be to
satisfy this need?

Would I need to slightly reduce the pupillary distance to make this
work better? By moving my current glasses down my nose when I read,
aren't I in effect reducing the PD? If that were the case, how much
would I have to reduce it by?

According to my records at the store where I last bought a pair of
glasses over five years ago, my PD is OD 30.5 mm, OS 31.5 mm. I did a
fair bit of looking and "trying on" at Zenni and was hoping to buy a
pair of glasses, but when placing my order I found that they don't
allow for two numbers for PD. How much difference will it make if PD
is off in each eye by 0.5 mm? I'm pretty sensitive and prone to
eyestrain.

Would going with a higher index lens and having a weaker rx mitigate
the PD issues to some extent?

Thanks,
Ellen

[Beaugrand®™©]

@Ellen,
Use 62 as the PD value, then in the "comments" window in checkout
specify "mono: OD 30.5 mm, OS 31.5 mm."
PD does not change with lens distance from the eye, it does vary due
to distance from the lens to the object you are viewing ( typically
adjusted down 2 or 3 mm for "reading" prescriptions).
With respect to the spherical values, I suggest you order several
$6.95 pairs (for example, the same style frame [like 4633**] in
different colors per value) with values -2.5, -2.0, -1.5, and -1.0.
Choose which works best for you.
This is NOT a substitute for a professional eye exam, which includes
much more than just determining the prescription. Your vision may be
changing due to higher blood sugar levels, so you really should go to
an eye professional.

WHL

[Annie He]

General way is, input your PD as 62 (30.5+31.5). And your glasses will
be fabricated with PD of 31/31 on each side. Most of people feels no
difference with +/-0.5mm offset. However, if you have a sensitive eye
and don't want to risk, you might contact with their customer to
customize your PD. OR you can give a trial to order a pair of glasses
with PD of 31/31. Hope that helps.

[RedStickHam]

I'm sorry to hear about your being housebound, but it sounds to me
like you may need a new prescription. My prescription is similar to
yours(-3.25 strongest with astigmatism), but my ability to read has
been declining it turns out I've developed presbyopia, which means I
need bifocals or to use reading glasses.

The amount you would need to change your prescription for reading
glasses is whatever is in the ADD box on your glasses prescription.
If your prescription doesn't have anything in that box, then you'll
need to get a new prescription and since you haven't had one in 5
years, it sounds like it's time for new one.
Zenni explains this and about PD in the Your Prescription section
under Info. Wikipedia also has a good article on Pupillary Distance
that explains near and far PD.

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

As for being 0.5mm off in each lens, I can't really say. I know
someone who purchased a pair of glasses that had an incorrect PD, with
one lens being off by 3mm, and they had problems in the lens that was
off. She got a Walmart optician to measure the PD for her using a PD
reader that the patient looks into like binocculars, and got
29.5/32.5. She had glasses made from that and in order to see out of
one eye without pain, had to push the glasses toward her nose. I
measured it using a paper ruler printed from one of the glasses sites
and with a PD ruler I found online, and did the measurement multiple
times and got between 58-60, so we went with 59, and her glasses seem
to fine. I'm a bit surprised by that considering I've never worked in
nor do I have any training in the optical field.

I hope this has helped you.

Good luck.

RedStickHam