Astigmatism - is axis of 0 possible?

[striezel]

I've got my new prescription and want to try ordering glasses online
for the first time (and save a bunch of money!). However, all of the
sites I have visited after reading the posts here won't let me input
my rx. The problem is the axis choices only go between 1 and 180 (not
zero). My rx shows:

OD: cyl -2.50 25
OS: -5 -0.50 0

The opthamologist said "cyl" in the first column is just to show
there's no myopia correction needed in the right eye, only the
astigmatism. Is 0 (zero) possible for the axis in the left eye or did
the doctor write it incorrectly? If zero is correct, I don't know how
I will be able to order since zero appears to be an invalid input for
the online vendors.

[Paul]

This article offers some clues:
http://www.company7.com/library/televue/Astigmatism_RX.pdf

After reading about this myself, I think that 0 is the same as 180,
just easier to write, but I think you should wait until you hear from
someone who knows for sure.

[Walter]

I am pretty certain you are correct. Actually, I believe it is
incorrect to use 0. I believe that axis values are supposed to be in
the range of 1-180, either plus or minus. This doctor seems to have a
rather unconventional way of writing his prescriptions.

[Paul]

Some doctors seem to develop their own shorthand. "0" is easier to
write than "180," and an optician would probably figure it out right
away. Though you'd think then that he'd write another "0" instead of
"cyl."

That is an unusual prescription, with a strong minus lens for only one
eye.