Is the optical quality of the eyeglasses I buy from a discount
optician, specifically Binyon's Eye World, as high as that from a
non-discounted optician? If not, what are the differences? Are some
discounters better than others?

I'm an ophthalmologist but I don't dispense glasses so I can't answer
your question with absolute certainty but I'm nevertheless quite sure
that there is no difference in the quality of the materials or how
they were ground.Everyone orders them from the same few labs.

If the "discount optician" is a large, rapid turnaround operation,
even though the same materials and machines may be used as with
"regular" labs, the discount optician may deliver a pair of glasses to
you that 1) do not match the prescription you provided and 2) do not
have the optical center etc. on the lenses measured for your eyes.  In
the field of optics, errors are made regularly in the making of
glasses.  However, these errors are usually caught in the quality
control steps that take place during production and the glasses are
sent back to be remade if there is a problem.  At the discount
opticians, this is less likely to happen and you may wind up with a
pair of glasses that you THINK are what you are supposed to have, but
they are not.  This may cause you vision and other problems.  It's a
risk you take.  You may get the right thing and you may not.  Good
luck.

JCG

There is no evidence, even anecdotal, that discount eyeglasses are in
any way inferior to any others.  The frames are cheaper, in general
not because of manufacturing issues but because they are not designer
or the very latest trend. The total package is cheaper because of the
huge decrease in advertising and other overhead.  The lens quality is
identical.  Very little in fitting is performed at the optician except
for centering measurements which are not critical except in very
strong prescriptions, gradient bifocals, and persons with certain eye
muscle abnormalities.  There is no reason to think that this fitting
is at all superior at high overhead overly priced establishments than
at individually owned optical centers!

It doesn't matter where you buy your glasses (expirences show that
small independt opticians are the better ones). What is more important
from which company the lenses are.
Lenses which come like from Lens Crafters are cheap Hong Kong imports
that don't go through any quality testing, so they stay cheap.
If you want a very good quality for your eyes i suggest that you buy
ZEISS lensens. These lenses are high tech products from Germany, there
not only induvidualy produced for your eyes, they also go througho
numeros stages of quality testing. ZEISS lenses are like the
Mercedes-Benz for your eyes and only can be fitted from a eye wear
specialist which receive a very long special training to fit these
lenses to your eyes. Thats why  big discounters cant do this and just
give you the cheap (bad for your eyes) lenses.

Other good lenslabs

single vision:
ZEISS
Essilor
SOLA
Rodenstock

progressiv lenses:
Zeiss
Essilor

Christopher Zoettl, B.s.O