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Medical Forum / General / Vision / August 2005Polycarbonate vs. regular/plastic lenses
I posted previously about the difficulty I'm having adapting to my new lenses. It also occured to me that I was never really all that happy with my last pair either, even though I wore them for two years. Thing is, that last pair is when I first switched to polycarbonate. At the time I thought poly was simply better in all respects, but after reading a little, it seems that poly is possibly more prone to distortion and such? Is it possible that poly is not the best choice for people who are more sensitive to distortion? With this new prescription I've noticed a slight but noticeable variation in clarity as I look through different parts of the lens, I'm not sure how normal this is, but I also wonder if there might also be an underlying distortion that is making me feel so disoriented. So what's the latest thinking on poly vs. plastic? If it's relevant, my prescription is like 0.25 power and 1.25 cylinder in both eyes. TIA > Is it possible that poly >is not the best choice for people who are more sensitive to distortion? > That's possibly the biggest understatement of the century. >If it's relevant, my prescription is like 0.25 power and 1.25 cylinder in >both eyes. TIA > It is, and makes me wonder what in the world were they thinking, unless you need special impact resistance afforded by polycarb, or unless you wanted a drill mount rimless frame. If either of those conditions do exist, then I'd say try Trivex material, which is even tougher than poly and the optics are way better. If neither exist, then go back to good old CR-39 plastic, the best optically. And while you're at it, ask them why they recommended them, with your Rx. w.stacy, o.d. Thanks for the reply. So I take it poly is known to cause distortion problems. The reason I originally went to poly (besides that it was sold to me as being great) was that my last set of frames was the drill-through type. I stayed with it because I still thought it was good stuff, and also because they suggested staying the course ("stay with what works") - even though it may not have really been working all that well previously either. What do you think a fair policy is regarding a change from poly to CR-39 as far as paying for it? Should I have to pay the whole bill for the new lenses? I doubt they'll be willing to pay the entire bill themselves since they didn't do anything wrong exactly. I also doubt that they'll even agree that the poly could be the problem. I suspect I'll get a few eye rolls before it's done ("oh, you read about it on the internet. I see..."). Until I read this NG I had no idea there were so many options for material. I thought it was glass, which nobody used anymore, plastic or poly. And the place I dealt with never really mentioned that any of them were better optically... >> Is it possible that poly >>is not the best choice for people who are more sensitive to distortion? [quoted text clipped - 17 lines] > >w.stacy, o.d. The redo is complicated by the fact that they are drilled rimless. If you stick with that frame, I'd ask for an upgrade to Trivex. They might let you off with the difference in price between the 2 materials. If not, then at least ask for a discounted redo. You can't really redo them in standard plastic unless you change to a grooved or standard mounting. If you are willing to change frames, you might get by with just the cost of the frame. Get creative and don't be bashful. Remind them that they didn't warn you that the ABBE value (amount of chromatic aberration) of polycarb is worse than just about any other lens material in the world. If they don't offer (or can't get) Trivex, why not??? w.stacy, o.d. > What do you think a fair policy is regarding a change from poly to CR-39 as > far as paying for it? Should I have to pay the whole bill for the new lenses? [quoted text clipped - 5 lines] > glass, which nobody used anymore, plastic or poly. And the place I dealt with > never really mentioned that any of them were better optically... oh, and also remind them that standard CR39 costs less than poly, so maybe they should refund you the difference after the remake... w.stacy, o.d. No, my situation is that I had drill-thru frames last time, but I'm switching to normal frames this go around. I never really liked the rimless frames, even though they looked good, because the center part was in my field of view so much. Right now, the lenses that are bothering me are poly in the regular frame. The question is whether they will consider switching to plastic worth the cost of trying, or if they will insist that something else is causing the problem - most likely me. I'll give it a shot and see. There's no reason not to stick with Crizal along with the plastic, right? >The redo is complicated by the fact that they are drilled rimless. If >you stick with that frame, I'd ask for an upgrade to Trivex. They might [quoted text clipped - 19 lines] >> glass, which nobody used anymore, plastic or poly. And the place I dealt with >> never really mentioned that any of them were better optically... >There's no reason not > to stick with Crizal along with the plastic, right? true w.stacy, o.d. Since you had worn polycarbonate in the past, why indeed are you now having problems? Perhaps there was a significant prescription change, or change in the base curve of the lenses? DrG Well, like I said, I was never totally happy in my last polycarb pair either. I always had a very subtle "cross-eyed" feeling when looking straight ahead. I realize this is all just speculation and could be something else entirely. It was also the first time I went with anti-glare (Crizal), but I doubt that would do it? My prescription change was that I went up from 1.00 to 1.25 cylinder in one eye. I believe that's it except for a minor change in axis on both eyes. They seem hesitant to hand out the exact numbers. I know they will if I ask enough times, but it seems that most people never ask. >Since you had worn polycarbonate in the past, why indeed are you now >having problems? Perhaps there was a significant prescription change, >or change in the base curve of the lenses? > >DrG Many pairs of polycarbonate lenses have been sold without complaint. It is one of the most widely used ophthalmic materials because of its thinness, light weight, relative impact resistance, and relatively low cost. However, complaints like yours -- if the prescription is correct -- are sometimes due to the higher aberrations (primarily chromatic) in this material, which are more prominent as the prescription increases. Since you mentioned a "cross-eyed" feeling when wearing your eyeglasses, you should have your eye alignment checked as well by an eye doctor. DrG This discussion has been helpful to me since I'm about to purchase a new pair of glasses, both lenses and frames. One place recommended Verilux and another talked about polycarbonate. No one ever says anything about known problems like distortion. How is the average consumer supposed to know what's best? Things have become so complex with so many choices. Is Verilux a good lense. I plan to do high index, progressive. If you look at my posts from yesterday, "New Progressives ? -- optican out of town, some of this is discussed. As I mentioned, my optican said the progressives should work for me and said if I didn't like them, he'd replace with glass for no extra charge. Perhaps you can find someone who will work a deal like that for you. My total cost, and I know, it is probably somewhat meaningless, esp. since I don't know what type of Varilux I have, was $346 for Esquire q-804 frames and polycarbonate Varilux lenses. Everyother shop in my area was at least $40 more and a couple were about $100 more. And they all felt like cattle call assembly lines. My optican runs his own shop, although he is "affiliated" with an adjacent opthalmologist. > This discussion has been helpful to me since I'm about to purchase a > new pair of glasses, both lenses and frames. One place recommended [quoted text clipped - 3 lines] > with so many choices. Is Verilux a good lense. I plan to do high index, > progressive. You need get straightened out about progressives. There are multiple brands of progressive lenses: Varilux, Rodenstock, Seiko, etc For each brand, there are multiple models: Vairlux Comfort, Varilux Panamic, Varilux Liberty, etc For each brand, there multiple lens materials available: CR-39 (1.50), Polycarbonate (1.59), 1.60, 1.67, etc. Please avoid polycarbonate lens material like the plague unless you need safety lenses, in which case I would look at Hoya Phoenix (Trivex) instead. An update: I went back to the place and they are going to switch me over to plastic free of charge. They gave me no grief at all, and the optician even said that he personally can't stand to wear poly. I sure hope this fixes my problem. By the way, I have a pair of sunglasses in addition to my regular poly glasses. The sunglasses seem noticeably less sharp i nthe right eye, most noticeable in distance vision. He looked at them and claimed the cylinder in the sunglasses was only 1.37 when it should be 1.50 in the sunglasses. He also said that there's no way I should be able to notice that. Do you gurus agree? It seems very noticeable to me. Oh, and I was a little off on my prescription. I had them write it down for me: OD PL -1.50x172 OS +0.25 -1.00x04 I'll try to remember to give an update when I get the plastic lenses. The sunglasses seem noticeably less sharp i nthe right eye, most > noticeable in distance vision. He looked at them and claimed the cylinder in > the sunglasses was only 1.37 when it should be 1.50 in the sunglasses. He > also said that there's no way I should be able to notice that. Do you gurus > agree? It seems very noticeable to me. You wouldn't notice that because it's well within tolerance, assuming he read it properly, so it's probably something else (could be the axis of that cylinder, which should be within 5 degrees of the Rx). Or it could be a distortion of some kind, or the Rx itself could be off. Whatever it is, if your clear ones are clear and it's the same Rx, the sunglasses are wrong in some way. w.stacy, o.d. I picked up the plastic lenses a few days ago. The weird thing is that I was actually starting to adapt to the poly lenses. I think I had had those glasses almost three weeks, but I was finally getting used to them - not totally, but mostly. Now I have the plastic lenses, and it's pretty different. It's not like they are better really, just different, so now I'm having to adapt all over again. I can't believe what a difference there is for the same Rx. On the plus side, the plastic clearly holds the Rx better as I look to the sides. The poly got blurry and weird looking if I didn't look through the center part of the lens. Needing glasses is a drag! |
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