aberration in polycarb hi-index lenses

[Maru]

Hi!

I'm trying on a new pair of polycarb Quantum transition lenses (-6.75/-6.50; -0.75 cyl). I've been wearing eyeglasses for more than 25 years so I know it takes from several hours to a day (for me at least) to get used to the "feel" of new lenses. However, I also know from experience that my discomfort when trying on new lenses, is limited to things appearing bright and sharp and the floor looking as if it's a bit farther down.

My new polycarb lenses have a different feel to it. First, it's like looking through a window. I can "see" the edges. Second, fine prints are blurry. I find this odd since I expected (based on previous experience) that with new lenses that have a higher Rx (higher by -0.5 and -0.25), I'd be getting dizzy from seeing things very sharply, not blurry.

I have one question - Is this kind of abberation common to polycarb lenses? I've never worn polycarb lenses before. I've only had one pair of plastic (can't remember the material) lenses before but I've always preferred glass although they are heavier. This is out of topic but I just prefer glass because of the clarity and scratch resistance (I'm your ideal eyeglass wearer. I never dry wipe my lenses. I always rinse them in the morning with water, soap with diluted dishwashing liquid, clean between the nosepads and the temple hinges too, and then pat dry with tissue. I find the microfiber cloth that's usually included in the case is not absorbent enough to remove the water without smearing the lenses.). Anti-scratch coated plastic lenses, even with the gentle cleaning treatment above, is not scratch-proof. My past experience with plastic lenses is that the scratch marks are so fine that I can only see them when they're held up against the light at an angle. They're also only apparent when I'm actually wearing the eyeglasses - gives the sensation that I'm looking through a frosted glass pane.

I would like to take these lenses back to the optical store but would like to know more about polycarb lenses.

Thank you.

Maru

[Happylady]

If you are over 40 years old more minus can make fine print blurrer.

Glass lenses have the best optics. Many people wear poly lenses with no problems(me included) but the optics are different then glass. Standard plastic has optics closer to glass lenses but some sensitive people can tell the difference.

Give it a few days and then go back to your optician if you are not adjusting.

[Maru]

Ok. I'll give it a few days.

I'm not over forty yet. I still have my current eyeglasses (glass lenses, -6.00 and -6.25; -1.00 cyl) and the prints are not blurry when I use them.

[Andrew Weiss]

I second Happy Lady, and suggest maybe a couple of weeks before you decide that you really haven't adapted to poly.

[Jim Stone]

Take them back and ask for NON aspheric. This should clear things up. The poly aspheric transitions are not much good for looking thru. If you don't NEED poly you should not get it.

[chip anderson]

Doesn't anyone hear this lady. She is telling you exactly what Chris and I have been saying for some time. Opticly, Glass is highly superior to any plastic, especially Poly. Plastic can amass infinitessmal fine scratches in a short period of time with good care.

Chip

[Jim Stone]

Take them back and ask for NON aspheric. This should clear things up. The poly aspheric transitions are not much good for looking thru. If you don't NEED poly you should not get it.

What this customer needs to do.

[loncoa]

Ma'am, are there any reasons you might not want to wear glass? Have you ever had a glass lens in your -6.50s? Just curious.

[Maru]

I've only worn plastic lenses once. In my 25+ of wearing eyeglasses, I've worn mainly glass eyeglasses. I've had glass lenses with -6.50 (also -6.75) Rx.

The reason I had to switch to polycarb was since I moved here, I find glass lenses are not common and not preferred by optometrists and opticians. I first asked for glass lenses but the store staff just kept insisting on polycarb and its virtues (forgetting to mention the downside in terms of clarity) that I caved in. Worst change of mind I ever made. The lenses were badly cut too. Compared with my glass lenses which had almost even thickness all throughout and nice soft edges, my new polycarb lenses are thin at the center but steeply curves towards the edge so that the edge is a lot lot thicker that they look like they have wings (imagine goggles with their thick sides). Edges are sharp too.

I had the lenses made in the US. I'm a graduate student here so I don't really have a lot of private funds and no supplementary health insurance to cover >CAD$600 for a pair of eyeglasses here in Canada (back home in the Philippines, would you believe that titanium frames with magnetic clips and hi-index AR-coated glass lenses cost me just CAD$90?). That's why I asked my friend to have my lenses made in the US. Problem is the store only exchanges lenses if they made a mistake in Rx and PD. They don't want to cover poor craftsmanship.

Anyway, I'll wait and see what the store says.

[Lady Nicole]

I've only worn plastic lenses once. In my 25+ of wearing eyeglasses, I've worn mainly glass eyeglasses...

..... I first asked for glass lenses but the store staff just kept insisting on polycarb and its virtues (forgetting to mention the downside in terms of clarity) that I caved in. Worst change of mind I ever made. The lenses were badly cut too. ....

....Problem is the store only exchanges lenses if they made a mistake in Rx and PD. They don't want to cover poor craftsmanship.....

Maru, you need a new place to buy your glasses. I don't care how many virtues polycarb has, it is not a suitable lens choice for a lifetime glass wearer. And the fact that they won't redo the lenses is &*^! service. Maybe there's no mistake in Rx or PD, but there was a definite error in lens recommendation.

Since you have them, I'd say try to give it some time and see if you start doing a little better. If not go back and try again with the store. Good luck to you!

[Doug Nutter]

I've worn my pair of Detroit Optical Polycarbonate hard coated lenses for 6 years - I'm 52, they are single vision -7.75. I am reasonably sure they were hard coated with a plasma diamond-like coating (PECVD I think...).

The plasma hard coatings are equal in taber abrasion to glass. There are some newer thermal cured hard coats that are very good, but likely not quite as hard as the plasma coatings - but I am not sure who now offers plasma hard coatings on eyewear.

The ONE BIG advantage of Polycarbonate over ALL materials - 100% guaranteed - is UV protection.

For some reason I don't really understand, very few people a) understand this or b) get the benefits -

For me personally, I use to wear glass lenses (for say35 years) and tried and do not like CR-30 plastic lenses - and would have to wear sunglass clips. I even tried the graded glass - darkened outside - but glass absorbs only 50% of UV - Polycarbonate and its coatings, absorb 99.995% -

If you are concerned about UV damage to your eye - and no longer want to "squint" with clear glasses in bright sunlight - the Polycarbonate is the way to go ...

I think that commercially the Zeiss Carat Advantage might be the best Polycarbonate coating available - but I know it is a thermally cured hard coat..

[Chris Ryser]

Doesn't anyone hear this lady. She is telling you exactly what Chris and I have been saying for some time. Opticly, Glass is highly superior to any plastic, especially Poly. Plastic can amass infinitessmal fine scratches in a short period of time with good care.
Chip

Besides the safety aspect.........of being able to hammer a nail trough a polycarbonate lens without it shattering into a thousand pieces, like Bob Bieber used to demonstrate in the 70s, which makes it a good material for kids, .....................poly is the cheapest material used in the optical world.

It's manufacturing cost is peanuts because it is automatically injection molded, same as a plastic spoon, fork or knive you use at parties. It's surface is so soft that you can scratch it with your thumb nail, that is why is has to be hard coated.

All the big hype advertising has made inroads for the sale of this lens material which is the big money maker for the ones that make it, the ones that work on it and the ones that sell it.

Furthertmore, being of a higher index it also requires flatter base curves which changes the feel of the visual picture a myop sees when switching from glass or CR39 (which is the closest to glass) to poly. Then you can mount them into a small frame which reduces your field of vision and you can see the edges or the rim in a disturbing way.

Conclusion:
If you are concerned about safety first.....well then........get yourself polycarbonate lenses.

If you are concerned with good vision..........well then stick with the material you were comfortable with.

[Happylady]

Doesn't anyone hear this lady. She is telling you exactly what Chris and I have been saying for some time. Opticly, Glass is highly superior to any plastic, especially Poly. Plastic can amass infinitessmal fine scratches in a short period of time with good care.

Chip

Yes, I heard what she was saying. I would never put a glass wearer in poly. I told her glass had the best optics with standard plastic a close second.

However, as she already had the glasses and was wearing them I thought it made sense to try them for a few days and go back if she doesn't adjust. It is amazing what people can adjust to in a few days. I figured she would probably have to have them remade but why not wait and see.

[shellrob]

Happylady....I'm with ya. Just because she's worn glass in the past doesn't mean she cannot wear the poly. Because a patient is experiencing the things described here when first getting the glasses, some just can't wait to jump at the chance to slam poly and praise the ever godly glass. Give me a break. We all know that optically glass is better, but there are other options and I'm certain that with some given time, she will adapt to something other than glass. Now, if some old school optican out there tells her that nothing else is as good as glass or that she won't see out of another material as good as glass, then she probably won't because some optican told her that and has planted the seed that there's nothing better. It's the same as a patient being told over and over that progressives are hard to get used to or had friends or family members tell them how horrible they were. We all know that with the poper given time, they could adapt but won't because someone has told them how bad they are.

[Chris Ryser]

Now, if some old school optican out there tells her that nothing else is as good as glass or that she won't see out of another material as good as glass, then she probably won't because some optican told her that and has planted the seed that there's nothing better.

It is not a matter of glass or some other material................The old school opticians seem to be less motivated to sell whats more expensive and brings in more money....................basically because of greed.

The old school opticians has learned and gained the expierience over the years and that patients return and send their friend to him, because he sold them a pair glasses thar they were comfortable as of the first second the put them on their nose.

The young optical sales person is motivated by selling products which are offered and higly promoted with advertising brainwash by the lens manufacturing industrie, because there is more money in it for all of them.

On top of that, the younger generation does not realize that the majority of their customers are older people, that in general have a harder time to adapt to something different from feel to looks.

To come back to glass.............these days the closest to glass and very compatible are CR39 for normal prescriptions, but that is the cheapest solution and the best in this case. But it does not seem to be anymore in the train of thought of the business and higher price oriented young opticians.

The most successful ones are those that suggest the patients the materials and types of lenses that will make them good as of the first moment, even if it might cost less.

[Jubilee]

So when I have a patient who is wearing a traditional glass bifocal come in and ask why didn't we recommend to him a progressive plastic lens because he buddy swears by them...

I should tell him that he is too late and will never like the optics of either a progressive or a plastic lens?


Should I tell my dad that he is weird for liking the lightweight poly lenses he has, when he wore glass for 30 years before that?

How about my hubby who wore PGX in the 70's-80's?

Yes, some people like and won't be willing to give up the better optics glass lenses provide..

On the other hand, there are many people who are willing to compromise a bit for the sake of fashion and comfort. Or don't even notice the difference.

That is why I have a conversation with each patient to discuss their wants, need and then choices and the pros and cons of different materials and lens designs.

The let them make the decision.

Sometimes they WANT the more expensive option..for whatever benefit they perceive.

AND now a days Glass is becoming more expensive to process than either plastic or poly. Fewer labs are handling it, so it takes longer to get it and requires different materials for production than any memeber of the plastic family.

Cassandra

[shellrob]

I'm motivated to make my patient happy, not sell them the highest priced lenses available. I don't have the non-adapt to progressive and material issues that some have on here. It just doesn't happen very often. I cannot even remember the last time I had a non-adapt to a high index material. If you educate the patients on what to expect from a new product, the issues don't come up. Lack of education once again.

[Robert Martellaro]

My new polycarb lenses have a different feel to it. First, it's like looking through a window. I can "see" the edges. Second, fine prints are blurry.

The increased awareness of the lens edge might be due to decreased lens size, the addition of a rolled or polished edge, or an increase in the distance from the lens to the eye. If the latter, it's likely that the lenses/OCs are also too high relative to the pupil center. If true, and the panto is a typical 10 degrees, the lens powers will be incorrect regardless of the lens material used. In addition, if the OCs are too high, there will be increased lateral chromatic aberration on the downgaze when reading, resulting in increased blur above and beyond the power errors caused by incorrect lens positioning. LCA can be reduced by using less dispersive (higher abbe number) lens materials and by decreasing the reading depth/occular rotation.

[Michael Walach]

Low Abbe value in Poly (about 30) induces longtitudinal abberation which causes increasingly blury focus as the lens power and prism increases. Hi index of refraction is the cause of hi reflectance. Reflectance can be virtualy eliminated by AR. The hi chromatic abberation, thus loss of sharpness, is there to stay. Try PROZAC...:)

Michael Walach