I would like to hear from folks on their opinions on polycarb, compared to other materials and has their use increased. The optical industry is really pushing polycarb and it's safety features. Does anyone have direct experience with a broken lens that caused serious injury?
Although Poly has some inherent benefits over traditional lens materials, it has not proved to be the nirvannah to all of the optical demands of our patients.
Our biggest problem with poly is when used with hyperopes over +3D as it begins compromising optical performance with abberation. Manufacturing poly is harder on our edger and must be segregated from edging other materials to reduce scratching.
Unfortunately the supply side has not been responsive to all the needs of retailers and therefore have caused us to begin considering the development of the newer materials affording the same benefits of poly.
We recommend poly for all children and for folks using their eyewear in an environment where impact is a possibility as per our "Duty to Warn" We only use polycarb lenses with our rimless eyewear styles and build it into the price of the frame so it isn't another "Cha-Ching" for the patient.
Our doc recently finished treating a woman who fell from a curb at a local supermarket last winter wearing a pair of PGX glass lenses which cut her cornea. Something probably preventable if she would have had her eyewear updated by a competent optician within the past 10 years who recommended poly as an alternative material. Her eyewear was over 15yrs old with many scratches but due to her misfortune received new eyewear with polycarb lenses compliments of the stores insurance company.
Back on my soapbox.
Where have you folks been? Poly is currently about 50% in chains and 20% in independents practices.
Of course, that's because "independents" know the inherent problems with the optics of poly. Plus 3? Gad, yes. But, how many patients do you see with a +3? Plus (no pun indended), what are the options. A fat CR-39? A thinner 1.60 with virtuallly the same optics?
About 90% of patients fall between (combined) powers of +/- 4.00. Take CR-39, add the cost of a SRC and UV attenuation and compare it to poly. If you're being fair, poly is far and away the best value. Plus, you have the added benefit of thinness--THE NUMBER ONE FEATURE IN PATIENTS SURVEYS!
Poly has the additional benefit of being impact resistant but, how many of you have ever had a patient ask for a lens that will stop a bullet? Non issue. If protection is a factor--in, what 5% of your patients?--poly or Trivex are your products of choice. For the other 95%, not the reason to recommend poly.
Is it for everyone? Heavens no. Nor is any other one product. That's why you're even here and asking question on Optiboard...to learn. To learn to offer the BEST options to EVERY patient who comes in your doors. And, they're all different. If it was easy, they wouldn't need you. Keep asking and keep leaning.
Sorry for the soapbox diatribe.
What do you do for the patient who says: I just want the best vision possible? Launch into a saftey/thiness pitch?
Chip
(Unfortunately, the answer is GLASS.)
What do you do for the patient who says: I just want the best vision possible? Launch into a saftey/thiness pitch?
Given the "duty to warn," you do have to give a summary of the "safety" pitch.
What I don't understand is the sanctimonious attitude of some dispensers who wouldn't DREAM of recommending polycarbonate (because of its horrendous abbe value of what, 31?), but take great pride in offering their clientele the "superior" performance of 1.66 products (with their stellar abbe value of what, 32?). Get with the program, folks!
The fact is, abbe values in the low 30's pose NO problem for the vast majority of patients with moderate Rxs (+2.00 to -4.00). Why? Chromatic aberration is a function of abbe value AND prism! Lower to moderately powered lenses simply do not provide enough prism in the near periphery to produce enough chromatic aberration to impact the vision of most people.
Why has polycarbonate become so popular (especially with chains and manufacturers)? It is inexpensive to produce when compared to lenses with similar features. It is light, thin, has a relatively high index (1.586), blocks UV, is easy to manufacture, and comes in a high quality form (thanks to the CD industry, who spent the money to make polycarbonate what it is today).
Like Jim so eloquently said, NO material is for everyone. However, benefit for benefit, polycarbonate is simply the best product out there right now- for the money. THAT explains why usage of poly grew through the 90s.
Trivex, IMHO, is one of those "gee whiz, that's neat" products. It is light and impact resistant and shows that polycarbonate isn't the only material out there with those qualities. However, it still poses some of the negatives of poly from the surfacing/finishing aspect, is a challenge to manufacture, and costs more than other products with equivalent or superior benefits.
Truth be told, the woman who fell at the supermarket would probably have fared just fine with CR-39 lenses- which do not easily shatter. The fact that poly is EXTREMELY impact resistant is simply a side benefit to this truly awesome material.
Well, that's my soapbox rant. If you don't like polycarb for some reason, that's fine. Just don't pratter on about the inferior optics of poly while you sell other high index products with similar optic characteristics... As Chip indicated, if optics is the ONLY concern, no product introduced this century has managed to do better than the optical performance of Crown Glass (and yes, I HAVE recommended glass to certain patients who truly did value optical performance over all else- AFTER informing them of the negatives of glass).
Pete Hanlin, ABOM
Vice President Professional Services
Essilor of America
http://linkedin.com/in/pete-hanlin-72a3a74
A young man with 20/20 wearing NON-RX sunglasses (in glass-well-known & reputible firm) is on his job (delivery & pickup of large items for a furniture store) is securing the item on the bed of the truck with a bungee cord and it fails to be anchored correctly. It flys back. SNAP! The glass lens shatters. The young man loses vision in the one eye.
Same young man not wearing glasses whats the outcome....optigoddess said:
A young man with 20/20 wearing NON-RX sunglasses (in glass-well-known & reputible firm) is on his job (delivery & pickup of large items for a furniture store) is securing the item on the bed of the truck with a bungee cord and it fails to be anchored correctly. It flys back. SNAP! The glass lens shatters. The young man loses vision in the one eye.
You just cant say because he was wearing glasses thats the reason he will lose his sight.....
In any case you should never use bungee cord to secure anything inside a van....Always use ropes...
A young man with 20/20 wearing NON-RX sunglasses (in glass-well-known & reputible firm) is on his job (delivery & pickup of large items for a furniture store) is securing the item on the bed of the truck with a bungee cord and it fails to be anchored correctly. It flys back. SNAP! The glass lens shatters. The young man loses vision in the one eye.
I respect what you are saying, but if we eliminated every potential hazard in our lives, we wouldn't enjoy many of the comforts of modern life (automobiles, jets, plastic bags, swimming pools, etc.). Every day of life has its calculated risks. Yes, glass can shatter- but it can also be used to provide better vision than any other material available. So, it comes down to a benefit vs. a risk- just like everything else in life. Fortunately, for most people the benefit of marginally better vision and increased scratch resistance do not merit the downsides of increased weight and decreased safety...
Pete Hanlin, ABOM
Vice President Professional Services
Essilor of America
http://linkedin.com/in/pete-hanlin-72a3a74
Jim G said:
Poly has the additional benefit of being impact resistant but, how many of you have ever had a patient ask for a lens that will stop a bullet? Non issue.
Regrettably we did last week!!
A patient in his 20s, he's quite myopic (about -6.00 ou) and has been coming to us for a few years. He came in during the week helped by his father.
He could hardly walk, his leg was in a splint, one of his arms was in a sling his head had been shaved and operated on, face badly marked and he was speaking badly, almost slurred.
As I said, we know him and were shocked to see him like this.
His father told us he was lucky, he had been in the cafeteria in the University in Jerusalem 6 weeks ago when 16 people had been killed by a suicide bomber. He doesn't know how he survived as he was sitting much closer to the bomber than others who were killed, maybe it was the angle he was facing.
One thing for certain, he will be maimed, disfigured and physically restricted for life.
He has only just been temporarily released from hospital, mainly to get new specs, but he has to return for a series of operations and procedures later.
He was wearing 1.6 plastic with AR. Lenses we supplied about a year ago. CT 1.0
He does have corneal scarring, not central fortunately.
Considering the physical damage his body had received, the lenses were complete, yes, scratched but nothing broken.
We did speak about Poly, but in the end he went for 1.6 again.
Clive,
While we're somberly remembering the tragedies that visited our country last year, so many of us forget that Israel (and many other parts of the world) live with this stuff all the time!
I would relay a hope that the Mid-East situation be resolved, but considering the fighting has been going on for centuries (even millenia)...
What's wrong with these people??? :angry:
Pete Hanlin, ABOM
Vice President Professional Services
Essilor of America
http://linkedin.com/in/pete-hanlin-72a3a74
Although a 1.66 may have an abbe comparable to poly, 1.60 is noticeably better and Spectralite is quite good. The real problem is that most opticians don't really know about the abbe problems with poly (or very high index plastic) and can't give the customer the pros and cons so they can make an intelligent choice. Most opticians claim the only disadvantage of poly or high index material is cost. My own personal experience is that poly is definitely not viable for PAL high + Rx's. Not many opticians that I have run into really know this.
My own personal experience is that poly is definitely not viable for PAL high + Rx's. Not many opticians that I have run into really know this.
As you can probably tell, I'm a pretty big poly fan. However, I will concede that high minus (or plus, really- which we don't see that often) PALs do constitute a contraindication for the use of polycarbonate.
As we all know, for low abbe value to become an issue there has to be a significant amount of prism involved. Even with most higher Rxs, the wearer rarely looks more than 20 degrees (about 10mm) from the center of the lens. In a PAL, however, the patient is spending a LOT of time 15mm- or more- from the O.C. At this point, the low abbe value of poly CAN become an issue and cause poor Relative Visual Acuity.
For most Rxs and applications, however, abbe value is simply NOT an issue. Something like 80% of all Rxs fall between -4.00 and +2.00. Within this range, polycarbonate (when processed correctly) provides excellent optics (optics which are certainly as good as 1.6, 1.66, 1.7 and mid-index materials).
Poly- more than a material- its a way of life!
;)
Pete
Pete Hanlin, ABOM
Vice President Professional Services
Essilor of America
http://linkedin.com/in/pete-hanlin-72a3a74
Now that there is an alternative that is optically better and just as safe, why is there not a drop off in poly sales and a large uptake in Trivex...Pete Hanlin said:
Poly- more than a material- its a way of life!
;)
Well money comes to mind, but just how many patients are given the choice of the 2 materials...Very few i bet as the optician (for want of a better word) will see some of his profit margin dissapear..
Wonder just how long poly will be around ?? all the time companies are pushing the next new thing thats better than sliced bread, yet here we have a product that can be seen as miles better and what do we here...Just about total silence....
These companies should be hitting the advertising to joe public hard.
Currently only Hoya and Younger have licenses from PPG to use Trivex and they are charging very high prices. Licensing to other companies is promised, but in the meantime prices are higher than most people are willing to pay. Furthermore, Hoya and Younger probably do not have the best PAL designs on the market, so consumers have to choose between the best design and the best material.
I suspect that the odds of someone being involved in a auto accident because of poor peripheral vision from polycarb lenses is far higher than the odds of them being seriously injured from shattered plastic. People who wear glasses while playing sports may be different issue, but for most people the impact resistance benefits of polycarb is way overemphasized.
"For most Rxs and applications, however, abbe value is simply NOT an issue. Something like 80% of all Rxs fall between -4.00 and +2.00."
Perhaps, but what about the 20% who don't fall into that category? I guess they just get screwed. My experience is that most opticians, whether independents or chains, don't have the intellectual capacity to differentiate between the those who will do well with polycarb and those who will not.
My prescription is r:-5.75 -.75 160 and -6.75 -1.25 025. I have always had a problem with depth perception and distorted peripheral vision with polycarbonate lenses, which I wore from childhood until I converted to high-index glass lenses. Wearing them gives me as good peripheral vision (within the lens, of course) as wearing contact lenses. However, outof curiousity, I have decided to seriously look into alternatives to glass. Unfortunately, only one out of four optical shops I visited knew the details of the lens materials they sell. Of course, I will be buying only from that place. However, I want to learn as much as I can and through internet information-hunting, I have narrowed my choices of plastics to: zeiss claret 1.6 abbe36, seiko 1.67 abbe32 (brand recognition only), Hoya Eyas 1.6 Abbe42, Sola Finalite 1.6 Abbe 42. for glass, i'm looking at zeiss lantal 1.8 and corning clear1.6
What are your beliefs about which of these lenses provide the best optics? Provided that I select a small frame with the proper oc, is abbe value the main thing to look at?
Use the Essilor 167 preferably with Alize coating. You can't do better at any price.
Chip:D
As for the patient with the suicide bomber. In the middle east most suicide bombers use ball bearings (Hard chrome steel) for the projectiles in their vests and poly, or bullet-proof glass, or kevlar won't stop this. Most armor peirceing bullets are copper jackets around a hard steel core. The core penetrates almost anything it hits.
Chip
Last edited by chip anderson; 07-10-2004 at 04:07 PM. Reason: New comment
I agree.Originally Posted by Pete Hanlin
We use poly at least 90% of the time. I recommend it in the exam room and I wear it myself. What other product offers so many benefits. Thin, light, blocks UV, safe and affordable. I feel I am offering my patients the most lens for the money. Only rarely have I had a vision problem associated with switching someone into poly.
No less an optician than the late Joe Bruneni was a big fan of poly. The material has so many built-in benefits at such a low price that we've made it our basic lens of choice, period.
Hey, I'm a -6.00 myope-perfectionist- optometrist, so I should know. I've worn MR-6 and I've worn Resolution polycarbonate, and there just isn't that much of a difference. Admittedly, that's good poly vs. average 1.6, and I should get a pair of Hoyas Eyas or Sola's Finalite to compare with, since those are the premium 1.6's, but...
Polycarb is underrated. Sure we get the non-adapts. But they go into mid-index like Spectralite or Trivex if they don't like poly, not any other high index material. There's just not that much significant difference in abberation that you'd put a poly non-adapt into another high index.
Now, if the person is substantially above -6.00, we will consider MR-10 as an initial lens choice, if cost is not an issue. There will be a marginal improvement in chroma and thickness. I would wager, though, that a majority of those would accept polycarbonate as well.
It's diminishing returns, I believe, but true high index does have it's place.
Thanks for your advice.
Btw, I know quite a few people who are also pretty nearsighted and had difficulty with polycarbonate lenses. The ones I had were from pearle vision and while I do think they tried their best with frame selection, etc., I think the material has definite limitations and it's great that's not the only choice:)
I see that you are considering 1.67 index. I assume this is due your desire for decreased thickness. Polycarbonate and 1.67 have abbe values of 30 and 32 respectively. I do not believe you will see much difference in chroma (transverse chromatic aberation) between these two materials. However, there are 1.67 lenses that use an atoric design, Vizio by Sola optical is one example. The increased refinement in the visual field with an atoric design might be enough to overcome some the off-axis blurring due to chroma. Resolution is an atoric polycarbonate that might work well also. Keep in mind that hi-index glass can have low abbe values similar to polycarbonate. Zeiss 1.9 is 30, and some 1.8 indexes are as low as 25. It would be interesting to know which brand of hi-index glass lens you have been wearing.
What type of lens would be best for you? Hard to say with certainty, but it appears that weight and safety are non-issues. Thickness and minimizing chroma seem to be your primary concerns. If thickness is your #1 priority, I would try the Vizio lens. A 1.6 lens with an abbe in the low forties and a 1mm center thickness might be the best compromise between cosmetics and optical performance. Use an optician that pays attention to the horizontal *and* vertical lens position. The lens should fit very close to the eyes, just clear of the eyelashes.
Hope this helps
Robert
This isn't answering your question but no one with your degree of nearsightedness (or any for that matter) will have as much peripheral vision with forward lenses as they do with contact lenses.
Some forward lenses are better than others for perpheral vision but nothing will give you the peripheral vision of contact lenses (with the possible exception of eye surgery.
Chip:D
Dear Robert,
Thanks a lot! I agree...and have actually ruled out 1.67 indexes because of the lower abbe value. I was looking at 1.6 Hoya and Sola lenses as well as the Zeiss 1.8 glass. My optician just told me the Hoya has a slight yellow tinge--so that's out. For some reason, he likes Zeiss over Sola Finalite, and I would have to hunt for another optician that regularly uses Sola to get the higher Abbe. (The 4 other places I've called and visited either told me polycarbonate should be fine for me or didn't know what company's lenses they use, etc). Anyway, I guess I just caved in and ordered the Zeiss Clarlet 1.6 and he was careful with the frame selection. Sorry about the long tirade wondering about the abbe....but this can always be the spare pair. If you have any opinions about the sola 1.6 finalite, I'm all ears.
Of course wearing contact lenses gives me great vision, but I've basically stopped wearing them because of dry eyes and lifestyle change. When wearing glasses, seeing the frames and the uncorrected vision outside of them never bothered me. It's the distortion when not looking straight through the center of the lens that's always driven me nuts, slowing down my reactions to things before me.
With appreciation,
If abbe value is your main concern then why pick a lens with only a value of 10 better than poly. Really you should pick regular plastic with a 58 abbe value or regular glass with a 60 abbe value. That would give you a value of 26 to 28 better than the best poly. Make sure you do it with AR.
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