Optical Quality

[satori]

I am trying to figure out which online provider sells lenses with the
highest optical quality for both single vision and progressives. I
was useing Trivex in B&M, but have been disappointed in what I got
from Optical4less (1.67-glasses are fine just the difference in
optical quality is disappointing). I seem to get conflicting
responses from the companies when I inquire about abbe values. Here
is the response I got from goggles4u:

"Our 1.56 lenses are made of CR-39 material and the poly carbonate
lenses are 1.59 lenses and the abbe value for the lenses 1.61 and 1.67
is 42."

I didn't think it was possible to make the 1.61 and 1.67 lenses with
an abbe value that high.

Any insight would be appreciated. Below is my prescription.

Sphere Cylinder Axis Add Prism
OD (Right) -5.25 -2.75 100 - -
OS (Left) -5.75 -1.50 50 - -

[Paul]

CR39 has an index of 1.49, which is sometimes rounded up to 1.50. A
lens with an index of 1.56 may be made from a material very similar
but not identical to CR39. Its optical qualities would likely be quite
a bit better than polycarbonate.

[Chuck Knight]

Especially given the "self destructing frames" thread that's current
on the forum, you may not want to hear this...but Zenni is well known
for their optical quality. Their frames range from exceptional to
junky, but their optical quality is always top notch. Dead on the
prescription, and super-clear...definitely not the stuff you think of
when you hear "poly."

Try an $8 pair, and see if they meet your expectations. From my own
experience, and that of many others on this forum, it's hard to go
wrong with their full-rim frames, and my own experience with their
half rim frames has been great. Never tried the rimless, though.

-- Chuck Knight

> --
> Check us out at the oft-updated http://glassyeyes.blogspot.com!
>
> You received this message because you are subscribed to the Google Groups "GlassyEyes" group.
> To post to this group, send email to glass...@googlegroups.com
> To unsubscribe from this group, send email to glassyeyes-...@googlegroups.com
> For more options, visit this group at http://groups.google.com/group/glassyeyes?hl=en

[Marc]

There are many other reasons for poorer optical quality beyond abbe
value. Are you getting chromatic aberrations (rainbows at the edge of
the lens)? If so, then your lenses may have a low abbe value. However,
if you just have poorer vision overall, it could be lower quality
material or poor quality coating (this is common, especially for A/R -
there's a wide range in quality for A/R coatings, and $5 A/R is rarely
any good). If you don't have A/R, it could also just be the quality of
the lens material itself - Trivex is a patented material with limited
distribution, and so has greater quality control. Unfortunately, with
online, there's a "race to the bottom" for price, and sometimes that
translates into cheaper materials. I'd suggest checking out retailers
that sell around $40 average like EyeBuyDirect or Glasses Shop if
you're noticing a quality difference.

To answer your abbe value question specifically, 42 is an average abbe
value for 1.6+ lenses, so I think they're telling the truth with
regards to that. You might want to consider mid-index (1.56) if you're
having abbe issues - it has an average abbe value of 47. The Trivex
lenses you had from B&M would have an abbe between 43-45. The highest
abbe is available with CR-39 (58), but with your prescription those
might be too thick (although if you have a plastic frame, thickness is
less important because the frame can hide a lot of it). Poly has the
lowest abbe at around 31, and probably wouldn't be a good choice for
your prescription.

Marc