Polycarbonate versus High Index Plastic (1.67) lens help!

Hi all,

I just picked up a new pair of glasses from Lenscrafters. They
recommended Polycarbonate because it was apparently shatterproof etc
etc. My prescription is -5 and -5.25, so I think that's fairly high.
The frames are a lot smaller, almost a 40% smaller than my old (13 yr
old) frames. Here are some of the problems I'm seeing:

1. Keeping my head facing forward if I try to look at something
slighty to the right or left of me, it's blurry.
- eg. I can see my computer monitor fine. If look at the phone on
my desk, a foot away from the monitor, I can't read the brand name or
the function buttons, they're all blurry

2. Reading stuff on my desk, all the print (black) has a yellow
outline/halo. (Chromatic Aberration?)

Also for #1, when driving if I glance at my driver's side mirror
(without turning my head), I can't read the license plate info or for
example the word "TAXI" on a taxicab's hood.

The Lenscrafters person suggested I get "High Index Plastic", which is
a $100 upgrade. I don't want to get those and then find that they are
the same as the polycarbonate.

Does anyone know if these aberrations that I'm seeing is normal for
Polycarbonate? And would high index plastic lenses of 1.67 make a
huge difference? What about 1.74? Although, Lenscrafters doesn't
carry any lens of 1.74. I think Nikon makes a lens like that but
they don't carry Nikon lenses.

Any advice would be greatly appreciated!

Thanks,

Kevin

 

Hello,

It is surely obvious then; that the glasses are never a satisfactory
substitute for normal vision without glasses, and at best are an
immense annyoance although they may correct the condition, and at
worst they are of no value at all, and induce harm.

Discard the bad and aggravating crutches, learn to see perfectly
without glasses. This may be accomplished by playing with the rest
methods and imitating the normal eye.

http://en.wikisource.org/wiki/Perfect_Sight_Without_Glasses

 

Polycarb has the worst optics (lowest abbe value) of any commonly dispensed
lens material. It has an refraction index of 1.59. The nearest index plastic
is 1.60 which should be much better optically than polycarb, should be about
the same cost as polycarb (maybe slightly higher), and should have better
optics and much cheaper than 1.67. The only disadvantage with 1.60 compared
to 1.67 is that 1.60 will be a little bit thicker and hence a little bit
heaver.

Personally, I would invoke the 30 day money back guarantee and go to
Wal-Mart Optical (if you are very concerned about price) or a good
independent optician. Wal-Mart has some fairly good lens materials available
to them (although I am not sure about SV lenses) 1.74 is probably overkill
for your Rx, and generally speaking the higher the index, the worse the
optical quality (except for polycarb, which is the worst at 1.59 index).

If you must have safety glasses, find someone who dispenses Trivex material
(Hoya Phoenix material is one brand that is made of Trivex)..

 

Hey Mark,

Thanks for your response. I thought I had it but after reading your
response, I guess I was wrong. The higher the refractive index the
worse the optical quality? (Optics in physics was over a decade
ago). Basically the issue I have with the current set of lenses
(Polycarbonate) is the fact that I can't even move my eyes 15-20
degrees off center and it gets blurry. Also looking down at
black&white documentation, most of it has a yellow halo. Would the
plastic lens fix those issues at both 1.60 and 1.67 refractive
indices?

The price doesn't really matter, I would rather get it done right.
However, lenscrafters has been kinda disappointing so far. From what
I've read one typically doesn't use polycarb lenses for prescriptions
of -5 and greater.... well they should have recommended against it.
They specifically said "Oh this is the best lens for your prescription
and it comes with all the protective coatings blah blah". A co-
worker of mine got his frames from Wal-mart for almost the same price
I paid for mine at Lenscrafters, so I didn't even look into Wal-mart.

As for the money back gaurantee, I'm not 100% sure of that. I know
that they will fix any issues and even replace the frame/lens upto 30
days, in my case +10 days because the store manager gave me an
extension so I could research the "plastic" lenses.

Thanks,

Kevin

 

Mark,

Thanks for your resposne. I didn't realise that the higher the
refractive index the worse the optics. I guess I need to go back to
Grade 12 physics, that was eons ago. The issue I have with the
current lenses is that if I look 15-20 degrees off center it's all
blurry. Also, if I look down at a black&white document, the black
print has yellow halos on it. If I got the 1.60 or 1.67 plastic would
it eliminate the blurriness and halos?

Cost is not really an issue (within reason), I didn't go to Wal-mart
because I wanted quality... .but Lenscrafters hasn't proven that they
know a whole lot more about optics. From everything I've ready they
should have been pushing plastic lenses for a prescription worse than
-5, not polycarbonate. A co-worker of mine got a new set of glasses
from Walmart and he paid about the same as I did at lenscrafters.

About the "30 day money back guarantee", I'm not sure I can do that.
I know they will fix whatever is wrong, replace the frames, lenses
etc. They might not do a moneyback deal though. In my case the
manager of the store extended the 30 days by 10 so that I could
research the plastic lenses online.

Thanks,

Kevin

 

Yes, the higher the index, then generally speaking, the worse the optics.
You don't something (thinner lighter lens) for free (optically speaking).
The biggest exception is polycarb which at only 1.59 index, it has the worst
optics of any commonly dispensed lens, but it is a safety lens.

Unless Lenscrafters has changed its policy recently, they offer an
unconditional 30 day money back guarantee. Call another LC and ask them.

You might look at 1.67 VIZIO ATORIC SINGLE VISION with UTMC (Ultra Tough
Multi Coating, which is an AR coat). Or look at similar lens designs from
Zeiss or Hoya. Lenscrafters carries mediocre quality lenses. Call around to
various optical shops in your area to see what lens they carry.

 

And while you're at it, toss out those orthotic insoles and the knee brace.
Next toss out your false teeth and use the rest method to firm up your gums
to chew food. No need for the heart pacemaker either, so out with that.
Insulin, who needs it? You can control your blood sugar with your mind.

 

Hello,

Please, who are you?

Yes that is right: you are no one in particular!

 

Robert,

Thanks for the information. Do technicians at Lenscrafters even have
an optical hat? The comment I got before leaving the store the last
time was "We can switch you to a high index plastic, that should make
it better if it really bothers you but maybe it's something that you
need to get used to..... we could change your frame if you want.".

They're not giving me any details around the options. What they need
to tell me is why I see blurry outside of the focal area, why the
chromatic aberration etc.

When I asked if a bigger frame would make a difference, she said "a
little but not really".

Is this for High Index Plastic? Lenscrafters only carries 1.67, so
I guess its abbe value 32.

The frames I picked are plastic, full frames. So I don't think the
thickness matters all that much, not as far as seating it goes
anyway. Here's a pair very similar..

http://eyeglasses.go-optic.com/enlarge.asp?id=20312&cat=DFRAMES

I might have to just do the 100% refund and go elsewhere since these
techs don't seem to be very knowledgable OR even care about the end
result. So far it seems like all sales, great fronting but no
substance.

Kevin

 

Kevin,
You can find more info about lenses
In the thread "Surprised by OTC Reading Glasses"
Read posts by Mark A
It is very interesting
Lena

 

At best, there is only one decent optician in each Lenscrafters store, and
they don't work all the time. That is at best.

The rest of the sales people were selling shoes or apparel at a different
store in the mall last month.

 

Mark
What about the plus lenses?
Will Low-index +2D lenses (glass or plastic)
Look too thick ?

 

A plus 2.00 lens is moderately weak, and will not be too thick for a
mid-index lens (1.53 - 1.60). Plus lenses are thin at the edges and thicker
in the middle. Most people who have a problem with thick lenses don't like
the edge thickness, which is more of problem for a minus Rx (nearsighted).

If cost is big factor, you could even get 1.50 plastic, which has excellent
optics, but may not come factory coated (for UV or AR) and is going to be
heavier than the others. Don't get any coating that is not factory coated by
the lens manufacturer.

Glass is really too heavy unless you some special requirement for it. Trivex
(Hoya Phoenix) or any 1.60 plastic would be good. The Trivex is a safety
lens like polycarb, but with excellent optics.

 

Thanks
Lena

 

Hi, your prescription is almost identical to mine. I have worn
polycarbonate for years because of the durability issue -- I ride
motorcycles and cannot accept a material for my glasses that may shatter
in the event of an accident. I do not have any of the issues that you
discuss and doubt that high-index plastic will make any difference.

I am not an eye doctor so thus cannot tell you why you're having
problems, just that it's not inherent in the polycarbonate material with
your prescription strength.

 

Kevin,

I haven't read the lengthy follow-ups to this, but just in case my two
cents is worthwhile:
Five or seven years ago Lenscrafters recommended me the "Featherwates"
polycarbonate lenses, and I could tell something was unusual the
moment I put them on (this was not the usual sort of adjustment
issues). My vision is around -7.75 and -8.25. If I was not staring
directly out of the center of the lenses, everything became blurry,
and many things split into a variety of colors in my peripheral vision
(most noticeably at a sharp black line against a white). I can't
remember if I went back the same day, or the next, but after
explaining what was going on, the person at Lenscrafters admitted that
a percentage of the population (I forget how much, but enough to be
notable, I guess) had this problem with the polycarbonate lenses, and
they replaced them for free. (Sorry, I forget what material my
glasses are currently made of, instead.)
Best of luck solving your problem! To my knowledge the company is, at
least, aware of the problem and what lenses to offer that will not
cause it.

-Sarah