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Medical Forum / General / Vision / September 2005Color Fringes with new glasses
I am 51. I started wearing +1.25 glasses about 10 years ago, 1.25/1.50 bifocals 5 years ago, and my new glases are 1.75/1.75 with +.25 astigmatism. The new glasses have orange and blue fringes in the distance portion. The oculist adjusted them and they are a bit better, but the fringes are still there. The reading portion is fine, and the fringes are only when viewed through the very top part of the lens. The oculist says it is common, though less so with the antiglare coating I got, and I will get used to it. I suppose they are rather stronger than my old lenses, so maybe that is why I haven't had it before. What you think? > The new glasses have orange and blue fringes in the distance portion. It's called chromatic dispersion, and it varies with different materials. Impact-resistant polycarbonate is notoriously prone to it. In lenses, blue light bends slightly more than red, as if the index of refraction is different for each different color. In some materials, the spread is greater than others, as indicated by a constant called the "Abbe number." The Abbe number for polycarbonate is 30, and conventional "CR-39" is 58; higher numbers are better and indicate less chromatic dispersion. Bottom line, it won't get better but you may get used to it. If they're shop glasses it's better to put up with it. If you don't use power tools, you may want a different material. -MT >> The new glasses have orange and blue fringes in the distance portion. > > It's called chromatic dispersion, and it varies with different materials. > Impact-resistant polycarbonate is notoriously prone to it. Yes, they are polycarbonate. The oculist thought that was the right material for my presciption and lense size. > In lenses, blue light bends slightly more than red, as if the index of > refraction is different for each different color. In some materials, the > spread is greater than others, as indicated by a constant called the "Abbe > number." The Abbe number for polycarbonate is 30, and conventional "CR-39" > is 58; higher numbers are better and indicate less chromatic dispersion. > Bottom line, it won't get better but you may get used to it. If they're > shop glasses it's better to put up with it. If you don't use power tools, > you may want a different material. I do wear them while using power tools, so maybe it is the best choice. Thanks. > -MT >Yes, they are polycarbonate. The oculist thought that was the right >material for my presciption and lense size. > If your Rx was about +1.75, I think standard plastic may have been a better choice. Better optics, less money. But if you wanted extra light, extra strong, I'd go with Trivex. A bit more money, but way better than polycarb, which has the worst optics of all lenses commonly used. w.stacy, o.d. > I do wear them while using power tools, so maybe it is the best choice. > Thanks. >> >> -MT If you want safety glasses with excellent vision, then get Trivex lens material. This is sold as Hoya Phoenix,and Younger Trilogy lens materials. The only downside is that Trivex is not as thin as polycarb, but it is very light. If your Rx is 1.75, then Trivex would be more than thin enough. You will probably have to get Trivex at an independent optician that carries either Hoya or Younger (not likely at a large chain store). I would phone around town before visiting any specific optician. Don't ever let anyone talk you into polycarb for driving. If you want a separate pair of glasses for your shop work, then polycarb may be fine. The odds of you being injured or killed by poor polycarb vision when driving is much higher than the likelihood of being injured by using power tools with regular lenses (unless your job is use power tools). Polycarb kills. > Don't ever let anyone talk you into polycarb for driving. If you want a > separate pair of glasses for your shop work, then polycarb may be fine. > The odds of you being injured or killed by poor polycarb vision when > driving is much higher than the likelihood of being injured by using power > tools with regular lenses (unless your job is use power tools). Polycarb > kills. Well, you have my attention. Why does polycarb kill? I only see the color (and they are all that bad) through the top quarter of the lense, and I wouldn't expect to see much traffic there. And they are still satisfactorily sharp despite the color fringes. The reading part, which is the most powerful, is fine; no color fringes at all They reflect a faint blue/green image; I presume that is the anti-glare coating? It seems to be pretty much the same all over. As someone opposed to polycarb myself, I think the case was somewhat overstated. I suppose you could dream up a scenario where the severe chomatic aberration of polys could distort peripheral vision enough to cause an accident. Pretty much a stretch, IMO. The blue/green reflection is just the selective wavelengths reflected off by the AR coating. Nothing more. Normal. w.stacy, o.d. >>Don't ever let anyone talk you into polycarb for driving. If you want a >>separate pair of glasses for your shop work, then polycarb may be fine. [quoted text clipped - 12 lines] > They reflect a faint blue/green image; I presume that is the anti-glare > coating? It seems to be pretty much the same all over. >Polycarb kills. Now he tells me, I just ordered a thousand Duty to Warn handouts. :) Any chance you own a bunch of PPG stock? (kidding) Regards Robert Martellaro ~~~~~~~~~~~~~~~~~~ Optician/Owner Roberts Optical robopt@execpc.com ~~~~~~~~~~~~~~~~~~ "An expert is a person who has made all the mistakes that can be made in a very narrow field." - Niels Bohr Polycarb kills? Only if your glasses impale your forehead when you are struck by a steel bar going through your skull. Geez, lighten up on the hyperbole. The way I describe the distortion of polycarb to a typical patient is to remind them that airplane windows are made of polycarbonate. Their strength is amazing, and they can take a tremendous impact without breaking. But, as you know, when you look out the edge of the window, the optics are distorted enough to make the houses or the clouds look wavy and distorted. > Polycarb kills? Only if your glasses impale your forehead when you are > struck by a steel bar going through your skull. Geez, lighten up on [quoted text clipped - 4 lines] > out the edge of the window, the optics are distorted enough to make the > houses or the clouds look wavy and distorted. Polycarb has killed and severely injured many people while driving because of poor peripheral vision, than it has saved from non-industrial accidents. So yes, polycarb kills. If one needs safety glasses for working in an industrial environment, that is justified, but I would not use them for driving. > Polycarb has killed and severely injured many people > while driving because of poor peripheral vision, than it > has saved from non-industrial accidents. So yes, polycarb > kills. How did they poll the dead people? -Quick > Polycarb has killed and severely injured many people while driving because > of poor peripheral vision, than it has saved from non-industrial > accidents. So yes, polycarb kills. I'd like to know where your information comes from. By to the same logic, frames with wide temples can "kill", too. Should we take the guns away from all those shooters wearing poly? I can't tell any difference between polycarb and CR-39, in my prescription. -MT > Should we take the guns away from all those shooters wearing poly? Yes. There will be that many less guns around. I think wide temples are outlawed in many areas for just that reason... Re shooters, replace their polys with Trivex and they will appreciate it. You'll never get their guns away. You must have a pretty weak Rx. I'm no longer using poly for much of anything. w.stacy, o.d. >>Polycarb has killed and severely injured many people while driving because >>of poor peripheral vision, than it has saved from non-industrial [quoted text clipped - 8 lines] > > -MT Mark, Mark...put down the hash pipe and wake up and smell the burning CR-39. Are you aware of the fact that poly lenses are the "lens of choice" for ALL children's eyeglasses at Lenscrafters, as they are concerned about children being injured at play? I know of large pediatric optometry and pediatric ophthalmology practices that SPECIFY polycarbonate lenses on every prescription that they write. Period. Every script demands poly lenses. To say that the peripheral abberation of poly is "dangerous" is dangerous hyperbole. I have thousands of happy patients wearing poly progressive lenses in their rimless frames, and we have a a 10% remake/rejection rate. We put poly in every drilled rimless that leaves our practice, and that amounts to about 30 pairs of poly lenses a week. 27 of those 30 pairs are worn successfully. The other three probably read your diatribe! ;) > Mark, Mark...put down the hash pipe and wake up and smell the burning > CR-39. Are you aware of the fact that poly lenses are the "lens of [quoted text clipped - 11 lines] > a week. 27 of those 30 pairs are worn successfully. The other three > probably read your diatribe! ;) OK, if a child does not drive, then probably no serious harm done. But Trivex would be better. For the adults with progressive poly lenses, probably the reason not many complain is that most of them are killed in traffic accidents shortly after leaving your office. ..Nice rebound. > > Mark, Mark...put down the hash pipe and wake up and smell the burning > > CR-39. Are you aware of the fact that poly lenses are the "lens of [quoted text clipped - 18 lines] > complain is that most of them are killed in traffic accidents shortly after > leaving your office. > For the adults with progressive poly lenses, probably the reason not many > complain is that most of them are killed in traffic accidents shortly after > leaving your office. ....while dialing their cell phones. I agree with the Trivex statement, though. Excellent material. DrG > To say that the peripheral abberation of poly is "dangerous" is > dangerous hyperbole. I have thousands of happy patients wearing poly [quoted text clipped - 3 lines] > a week. 27 of those 30 pairs are worn successfully. The other three > probably read your diatribe! ;) Original poster here... My polycarb progressive bifocals are half rimless, with a wire underneath. Would you use polycarb here? I have worn them a few days now. The reading part is fine. The middle third shows a little color, but not enough to be a problem. It is the top third that is annoying. When I drive, the tops of trees have fringes. I can't see how that would cause an accident, except if I were thinking about it instead of the road; but it is annoying. The peripheral vision has fringes also, but I can't really see it unless I look for it, so it is hardly a problem. What to do, what to do... > Original poster here... > My polycarb progressive bifocals are half rimless, with a wire underneath. [quoted text clipped - 8 lines] > hardly a problem. > What to do, what to do... If they are under warranty or if the retailer offers a 30 day money back guarantee, take them back and get Trivex or some other lens material. Any other lens material. I switched out my polycarbs for Varilux Panamic 1.60 lenses, and there was a dramatic improvement in vision. But any lens material is better than polycarb. The point about the driving was not that you really are likely to have an accident with polycarb. But you are more likely to have a driving accident with polycarb than you are likely to prevent an eye injury because your lenses do not have very high impact resistance or tensile strength. But if you must have impact resistance or tensile strength, get Trivex (Hoya Phoenix or Younger Trilogy). An optician dispenses polycarb, especially for drill mounts or other similar difficult mounts, because they are less likely to crack and they will have fewer returns for that reason. They don't give a damn about your vision. I routinely fill such Rxs with Trivex, without bothering to call the prescriber. It's not my job to educate them. w.stacy, o.d. > Mark, Mark...put down the hash pipe and wake up and smell the burning > CR-39. Are you aware of the fact that poly lenses are the "lens of [quoted text clipped - 11 lines] > a week. 27 of those 30 pairs are worn successfully. The other three > probably read your diatribe! ;) >It's called chromatic dispersion, and it varies with different materials. and by the amount of prism induced determined by Prentice's rule. So if there is going to be a chroma problem I would expect it to be on the downgaze where there is more prism induced. I would ask another optician to take a real close look at the quality of the optics and the AR coat at the top of the lens(es). Hope this helps Robert Martellaro ~~~~~~~~~~~~~~~~~~ Optician/Owner Roberts Optical robopt@execpc.com ~~~~~~~~~~~~~~~~~~ "An expert is a person who has made all the mistakes that can be made in a very narrow field." - Niels Bohr I went back today and complained. He said 4 days was too early to say I didn't like them, but went at them with a pliers. The problem is reduced by about half. He said they were crooked. Hmm. >I went back today and complained. He said 4 days was too early to say I >didn't like them, but went at them with a pliers. The problem is reduced by >about half. He said they were crooked. Hmm. I lost the original thread. I'm just hoping you're not talking about an Intraocular Lens <g> >I went back today and complained. He said 4 days was too early to say I >didn't like them, but went at them with a pliers. The problem is reduced >by about half. He said they were crooked. Hmm. What problem? > >I went back today and complained. He said 4 days was too early to say I > >didn't like them, but went at them with a pliers. The problem is reduced > >by about half. He said they were crooked. Hmm. > What problem? Color fringes in polycarbonate lenses.
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