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Medical Forum / General / Vision / December 2006Problems with "poly" variants - can someone please explain?
I tried "poly" lenses 5 years ago and found them uncomfortable, so my lenses were switched to "plain plastic" and I've had no issues. I opted for new frames after a recent exam (same Rx) and went for Silhouettes. I was told that only poly lenses can be used in them. I reminded the optician about my previous encounter with poly, so he suggested Trivex. Well, they gave me problems. It fealt like what I remembered dirty contacts to feel like (20 yrs. ago). So, they ordered "hi-index 1.60" lenses. They are better, but I still have some minor discomfort after 4-5 days. I called my opthomologist and he said some people get used to "poly" and some never do. Ironically, my old lenses are sooooo scratched, yet that doesn't bother me except when it creates a large glare. My prescription is -250 -250. These lenses have polished edges. I have read a number of posts here, but lack the training to fully understand the issue and lens options. Can someone explain the difference between poly, Trivex, and high index? Also, are there are other lense options for these frames (I think they said 1.80)? And if I'm out of options, should I try to get used to them for a while or can this cause harm in any way? Thank you very much. BTW - I have also been wearing Oakley prescription sunglasses for about 4 years and they are the most comfortable glasses I've ever had and no issues at all. I believe they're "poly" so ??????????? > BTW - I have also been wearing Oakley prescription sunglasses for about > 4 years and they are the most comfortable glasses I've ever had and no > issues at all. I believe they're "poly" so ??????????? Poly is OK when there is now lens power. >I tried "poly" lenses 5 years ago and found them uncomfortable, so my >lenses were switched to "plain plastic" and I've had no issues. I opted [quoted text clipped - 20 lines] > >Thank you very much. Steve, On a -2.50 poly lens you would have to look 20mm off-axis to see any blurring due to transverse chromatic aberration (TCA). That's about forty degrees of ocular rotation, in other words you would have to really force your eyes to look that far off-axis. The discomfort is probably due to improper lens position. Check the vertex distance, vertical and horizontal OCs, panto, and look for warpage, waves and surface imperfections. Make sure the lenses have an anti-reflection coating, not that this will reduce chromatic aberration, it will increase the comfort with higher index of refraction lenses. Hope this helps, Robert Martellaro ~~~~~~~~~~~~~~~~~~ Optician/Owner Roberts Optical Wauwatosa Wi. ~~~~~~~~~~~~~~~~~~ "An expert is a person who has made all the mistakes that can be made in a very narrow field." - Niels Bohr Thanks Robert. The store went from my measurements on file from my plastic lenses and didn't check me for this purchase. Who should "Check the vertex distance, vertical and horizontal OCs, panto, and look for warpage, waves and surface imperfections."? Is that something the store should do or at this point does that require an opthomologist? > >I tried "poly" lenses 5 years ago and found them uncomfortable, so my > >lenses were switched to "plain plastic" and I've had no issues. I opted [quoted text clipped - 41 lines] > "An expert is a person who has made all the mistakes that can be made in a very narrow field." > - Niels Bohr >Thanks Robert. The store went from my measurements on file from my >plastic lenses and didn't check me for this purchase. Who should "Check >the vertex distance, vertical and horizontal OCs, panto, and look for >warpage, waves and surface imperfections."? Is that something the store >should do or at this point does that require an opthomologist? The optician. Robert Martellaro ~~~~~~~~~~~~~~~~~~ Optician/Owner Roberts Optical Wauwatosa Wi. ~~~~~~~~~~~~~~~~~~ "An expert is a person who has made all the mistakes that can be made in a very narrow field." - Niels Bohr >I tried "poly" lenses 5 years ago and found them uncomfortable, so my > lenses were switched to "plain plastic" and I've had no issues. I opted [quoted text clipped - 20 lines] > > Thank you very much. There are two kinds of lens that have high impact resistance and high tensile strength. One is polycarbonate, which has an index of about 1.59. Polycarb has the lowest (worst) "abbe value" of any generally prescribed lens (abbe value is 30). Abbe value is a measure of chromatic aberration, the higher the better. The other lens with high impact resistance and high tensile strength is Trivex (sold mainly by Hoya and Younger in the US), which has index of about 1.53. Therefore your lens will be thicker and heavier than a higher index like polycarb, but Trivex has an excellent abbe value of about 43. Some people say that Trivex has a slight tint to it, but if you put on a high end AR coating, then you may not notice it. I don't understand from your post above exactly what your problem with Trivex was, so it might help if you are more specific. Both polycarb and Trivex are very good for lenses that are drill mounted because of their very high tensile strength and resistance to cracking. Other "plastic" lens materials are available from 1.50 index (called CR-39, hard resin, or regular plastic) all the way up to about 1.74. usually the higher the index, the lower the abbe value (worst the optics), but the higher the index lenses will be thinner and lighter (because less material is needed for a given lens power). For a -2.50 (it is not 250) Rx, which is low to moderate in strength, getting a lens with an index higher than about 1.55 is not necessary to keep the lens thin and light. For the best optics, you should get the lowest index lenses you are comfortable with. 1.80 is not widely available in the US, and is completely ridiculous for someone with a -2.50 Rx (it might be needed if your Rx is -12.50) and is one of the few lenses that would be optically worse than polycarb. Trivex (1.53) should be thin and light enough for your Rx, and is very good for drill mounts, and has excellent optics. I would try to find out exactly what lens you have and exactly what was wrong with the Trivex lenses you tried. Most people who have tried Trivex are very satisfied with the optical quality. Mark, thank you for the detailed explanation. The moment I put on the Trivex in the store I felt discomfort, particularly in my left eye. Within 2-3 minutes of wearing it in the store for the first time, my wife and the optician noticed my left eye becoming bloodshot. Most of the time wearing it I would feel discomfort on my eyeball, as I said, like an irritation the way I remember dirty contacts to feel. Possibly, there was a little more tearing too. Today, I wore the 1.60 lenses for about 11 hours and they were bothering me to a lesser degree. Within 15 minutes of switching back to my old (same Rx) scratched plastic lenses the discomfort was subsiding. I can only imagine it has something to do with how light or the magnification is being presented to my eye (????) but that still leaves no path to a solution. Currently I'm trying to train my eye to these lenses, but today's "training" doesn't look promising. Still looking for solutions... > >I tried "poly" lenses 5 years ago and found them uncomfortable, so my > > lenses were switched to "plain plastic" and I've had no issues. I opted [quoted text clipped - 58 lines] > tried. Most people who have tried Trivex are very satisfied with the optical > quality. > Mark, thank you for the detailed explanation. The moment I put on the > Trivex in the store I felt discomfort, particularly in my left eye. [quoted text clipped - 13 lines] > > Still looking for solutions... I very much doubt your problem has anything to do with the Trivex lens material, if that truly is what you received. The number of errors in grinding lenses to the correct power and fitting lenses (for proper placement in the frame so it is optically centered) is much higher than you would suspect. And there are sometimes errors made during an eye exam by an OD. Any time you have a problem like you had with the Trivex lens, you need to take the lenses to another optical shop and have them measure the Rx of your new and old lenses. You also may need to move the frame around on your face to see if the lenses are the proper distance from your eyes, are at the correct angle, and are optically centered. Anytime you are dissatisfied, ask for a second opinion from a different optician or OD. Do not even talk to young sales people in a Optical shop, always talk to the most experienced person you can find. I would really like to know what kind of optical shop you have used (large chain, local independent, optical shop in OD office, etc.). Mark, thank you again. I originally was examined by an Ophthalmologist who confirmed that my existing Rx (-2.50) was still correct for me. I then went to the optician I have used for the past 6 years to get the glasses. They are located in a large mall, but I'm not sure that they are anything but an independent operator. They have been very cooperative, but again, used my on-file specs. for this order, without re-measuring. I've never had an Ophthalmologist provide anything but the basic lens power on the Rx, leaving the rest to the optician. The message I'm getting from you is that Trivex was a better product that may have been produced wrong for me. I basically asked about that and when I first went back, they measured them and said that they met the proper specs. (???) I called the opthamologist's office and they said a small # of people don't adjust to poly (I specifically said Trivex). I don't know where the Trivex lenses are now, but my understanding from you is that I'm on the wrong path with high index. The optician has a store credit only policy, so I'm bound to them. I would like to make these frames work for me but don't know who can determine the real issue or where to turn to resolve it? Are there people who don't adjust to properly made Trivex? > > Mark, thank you for the detailed explanation. The moment I put on the > > Trivex in the store I felt discomfort, particularly in my left eye. [quoted text clipped - 34 lines] > I would really like to know what kind of optical shop you have used (large > chain, local independent, optical shop in OD office, etc.). > Mark, thank you again. I originally was examined by an Ophthalmologist > who confirmed that my existing Rx (-2.50) was still correct for me. I [quoted text clipped - 19 lines] > issue or where to turn to resolve it? Are there people who don't adjust > to properly made Trivex? Given that Trivex has an abbe value of 43 and is considered to be one of the best materials in terms of optical quality, I don't think the Trivex material is related to your problem. It could be the lens design (lens make and model), the grinding of the lens, or the fitting of the lens in the frame so that it is optically centered. Trivex is not the same as polycarb, so I don't understand the comment from your Ophthalmologist about not adjusting (but Trivex is relatively new and not everyone is familiar with it). I would suggest that find out the exact make and model of the Trivex lens. There are only 2-3 lens suppliers in the US (Hoya and Younger are the main ones) that are licensed to use Trivex material. Personally, I would not recommend an ophthalmologist for an eye exam. They are medical doctors who spend most of their time with eye diseases and other serious eye problems, while Optometrists (OD) spend all their time doing eye exams. However, if you do have an eye disease, then stay with your ophthalmologist. I notice that you did not specify a correction for astigmatism in your Rx. Is that correct or did you just leave that part out of your post. It is somewhat unusual to need any correction for astigmatism, but not totally unheard of. Also, I am assuming that you have single vision lenses and not progressives, since you did not state an "add" power for the reading area. For a simple single vision -2.50 Rx, you should be able to easily find a pair of glasses that give you good vision without any problems. As I suggested earlier, if you have any doubts about a lens, then you should take them to another optician to have them measured. Or your could take the lens made by the optical shop to your ophthalmologist. Have them compare the old (good) and new lenses. When purchasing a lens, always make sure you know the lens manufacturer (Hoya, Younger, Sola, etc), the lens model, and the lens material. Otherwise you may be purchasing substandard products. If they don't know, or will not tell you, go somewhere else. You would not believe the number of mistakes that are commonly made in the process of making glasses, and the optician may not be able to recognize their own mistake. About 15 years ago, I purchased a pair of single vision lenses from EyeMasters (at that time owned by Sears). When I got the glasses, I immediately told them I could not see anything out the lenses. Several employees re-measured the lens power and they said it was correct. Finally, after much complaining, I found another employee who realized that the astigmatism correction (cylinder and axis) was ground backwards. This kind of gross incompetence is not rare. Thanks again. No disease/issues. Single vision. No astigmatism. Same Rx for at least 10 years. Oakley's "proprietary" poly Rx sunglasses no problem for me. So is there this issue that some people don't adjust to Poly? And if so, that doesn't apply to Trivex? Am I correct that the Trivex lenses have to be checked installed in the frames? > > Mark, thank you again. I originally was examined by an Ophthalmologist > > who confirmed that my existing Rx (-2.50) was still correct for me. I [quoted text clipped - 66 lines] > the astigmatism correction (cylinder and axis) was ground backwards. This > kind of gross incompetence is not rare. > Thanks again. No disease/issues. Single vision. No astigmatism. Same Rx > for at least 10 years. Oakley's "proprietary" poly Rx sunglasses no > problem for me. So is there this issue that some people don't adjust to > Poly? And if so, that doesn't apply to Trivex? Am I correct that the > Trivex lenses have to be checked installed in the frames? Some people are more sensitive to polycarb distortions than others, and it is more noticeable when the lens power increases. Moderate to high power plus lenses (+) have more of a problem with polycarb than minus (-) lens powers. If you have Rx sunglasses in polycarb, some of the problems (such as chromatic aberration) may be less noticeable because of the tinting. Trivex does not have the same problems as polycarb in terms of "adjusting" to the poor optics, because Trivex does not have poor optics. The only downside to Trivex is that it is lower index (1.53) than polycarb (1.59), which means that it is thicker and heaver for a given Rx, but that should not be much of an issue for a -2.50 Rx. Trivex also has a slight tint to the lens, but may not be noticeable if you have AR coating. Trivex is usually more expensive than polycarb, and only available from a few lens manufacturers, notably Hoya and Younger, (but maybe 1 or 2 others have recently starting licensing it). Do not be surprised if an optician claims they ordered Trivex, but actually ordered something else. Find out the lens manufacturer name and model number of all lenses your purchase, especially Trivex. Mark, you are a wealth of information! Do you work in the industry? I went to both the Hoya and Younger web sites to look up their info on Trivex and I don't see any listing for it. I see that PPG makes the material - do they use PPG material and then brand it? If so, do you know which is which? Also, I ordered both lense types with the Cryzal coating - any thoughts on that? > > Thanks again. No disease/issues. Single vision. No astigmatism. Same Rx > > for at least 10 years. Oakley's "proprietary" poly Rx sunglasses no [quoted text clipped - 21 lines] > the lens manufacturer name and model number of all lenses your purchase, > especially Trivex. > Mark, you are a wealth of information! Do you work in the industry? > [quoted text clipped - 3 lines] > know which is which? Also, I ordered both lense types with the Cryzal > coating - any thoughts on that? Hoya sells it as "Phoenix" and Younger sells it as "Image". If I had a choice, I would use Hoya Phoenix. Crizal, and the easy to clean Crizal Alize. are both excellent (durable) AR coatings. Crizal is made by Essilor, but is available on some other manufacturer's lenses also. But I would be a little suspicious of Crizal on Trivex, since Essilor does not offer Trivex. As I said, some labs will put Crizal on other lenses beside Essilor, but I would double check that. You should be able to get a finished -2.50 lens from Hoya that comes with a Hoya AR coating applied by the factory. A finished lens does not have be custom ground at a local lab, which eliminates one more variable in the process. > Given that Trivex has an abbe value of 43 and is considered to be one of the > best materials in terms of optical quality..... An Abbe value of 43 does not sound terribly good, as I find (using Google) that CR39 plastic has an Abbe value of 57.8, almost as good as glass. 43 is less than halfway between this and 35, the Abbe value of polycarb. Is there some other aspect of Trivex that makes it have good optical quality? Liz D. > An Abbe value of 43 does not sound terribly good, as I find (using > Google) that CR39 plastic has an Abbe value of 57.8, almost as good as [quoted text clipped - 5 lines] > > Liz D. Every polycarb that I have seen has an abbe value of 30. Where did you see 35? Actually, polycarb has some additional distortions (besides chromatic aberration) over and above most other lenses that are not measured by the abbe value. Yes, CR-39 (1.50 index) has a very high abbe value, but it is thick and heavy for someone who has more than a mild Rx, and most people wear high index lenses these days (usually 1.60, 1.67) which have an abbe rating of about 34-38. And of course polycarb (1.59) is often used and has an abbe value of 30. So an abbe value of 43 is quite good for a lens with very high impact resistance and very high tensile strength. This is an issue for the OP who wants drill mounts for his frame. Aside from being good for drill mount frames, polycarb and Trivex are the only lenses that are approved for those who need "safety" lenses, such as children, those who play sports with glasses on, or for someone who works in a lab or factory. In the US, all opticians have a "duty to warn" customers that they recommend polycarb lenses for children or for other people who have need for safety lenses. Often times polycarb is sold to minimize legal liability, rather than to provide good vision. > Actually, polycarb has some additional distortions (besides chromatic > aberration) over and above most other lenses that are not measured by the > abbe value. What would those be? Calling polycarbonate the worst possible material suggests you have a marketing agenda. The OP has not once mentioned rainbows, and had more problems with Trivex, it appears. As you said, "vertex distance, vertical and horizontal OCs, panto, and warpage, waves and surface imperfections" plus BC and frame shape and _all_ of those things are more likely to cause "discomfort" than polycarbonate alone. There are huge numbers of -250 poly wearers with absolutely no problems. Steve Y - we need to know more about the nature of the problem. Blur and discomfort aren't exactly the same thing, and poly, Trivex and CR39 aren't different enough to explain why you'd have major discomfort or blur in straight-ahead gaze. There are plenty of ways to screw up a pair of glasses and the ones that cause headachey discomfort are usually misplaced optical centers, waves in the lenses, big changes in base curve. I have to doubt your problem actually involves _blur_ because -250 is -250 and everybody's checked that. Vertical misalignment is a common cause of discomfort (asthenopia.) You can check this with a simple "cover test" wearing the glasses. Move your hand back-and-forth to cover first one eye, then the other. Pick an object far away and see how much it "jumps" vertically when you switch eyes. If it doesn't move up-or-down from eye-to-eye, then the vertical alignment is fine. (It can move a lot from side-to-side without causing problems; the up-and-down matters most.) I once got headaches with a new pair and everyone was puzzled why, until someone noted grooves in the skin at my temples. The frame was just too small. You haven't actually said "headache" but "discomfort" is too vague. Another cause - the lenses that correct your vision have the side effect of minifying, making things smaller. The closer they fit to your eye, the less they minify. Going from one pair to another frame with the same prescription often causes an adjustment (the "walls are curved".) But people usually get used to that, and you haven't described any such distortion. Bottom line - if you're going to figure out what's causing the problem, you need to clarify what the problem is. Blur? Rainbows? Walls curvey? Floor further away? Or is it more a headache, dull pain? Or double vision? What are the results of your cover test? -MT Mike, thank you for the added input and test idea. In my house now I can only test myself to about 40 feet of distance and for comparison I tested with both my old glasses and the new (currently) high index lenses. It's hard to say for sure what the exact results are but here goes: I thought sometimes w/the old lenses one eye saw the object a little larger than the other (??) but not much in the way of movement vert. or hoiz. Most of the time with the high index it seemed like there was a little change diag. affecting the object height a little. (??) Sometimes I wasn't sure. My eyes are tired now... Should this be done outside with real distance? I'm guessing this is only a preliminary means to make a judgement and that true lense measurements are needed. (??) As far as I can tell both the Trivex and high index lenses have been crystal clear to me. No blurring, no waves, and causing no headaches. The discomfort with the Trivex started (as I described) like the way I remember dirty contacts to feel (from 20 yrs. ago) - kind of itchy/irritating. Both lense types cause an ache in my eyeballs (feels like the schlera area) - particularly on the inner sides adjacent to my nose and sometimes towards the bottoms. As the hours pass while wearing the glasses the ache increases from a very mild discomfort to enough of an annoyance to put my old scratched up glasses back on. 15 minutes in those and the aching is disappearing. I believe the high index cause it less than the Trivex did, but I don't have the Trivex to compare side-by-side. I can't see wearing them day after day and having this discomfort, let alone wondering if there's a physical effect taking place on my eyes. I was a mechanical engineer w/NO optical training. So my layman's guess (emphasize guess) based on the way my eyes feel, is that they have to focus towards the outside (left and right) and strain the inner side. But of course I don't know. Thank you. > > Actually, polycarb has some additional distortions (besides chromatic > > aberration) over and above most other lenses that are not measured by the [quoted text clipped - 52 lines] > > -MT >> Calling polycarbonate the worst possible material suggests you have a >> marketing agenda. [quoted text clipped - 11 lines] >> There are huge numbers of -250 poly wearers with absolutely no problems. >> -MT MT, I did not respond to your original post, because I have you in my killfile for the absolutely ridiculous arguments you get into with the quacks on this forum. Or maybe you are one of the quacks, I don't even remember. But I did see that your post above is included on the response of the OP, so I will respond. Since I don't work in the optical industry, it is not even remotely possible that I have any marketing agenda. Polycarb, with an abbe value of 30, has the worst optics as any other lens that is generally dispensed in the US. That is a fact. Indexes beyond 1.74 is not widely available and not generally dispensed in the US. I never suggested that the problems of the OP had anything to do with polycarb, since (as you pointed out) he did not complain about "rainbows", swimming (which can occur with SV polycarb), or even peripheral distortions. Likewise, I suggested that the problems with his Trivex lens had nothing to do with the Trivex material. I did point out that Trivex is substantially better in terms of optical quality than polycarb (which is absolutely indisputable), even though they both share high tensile strength and high impact resistance. What I did suggest (in multiple posts) is that his either Rx is bad, or the lenses were not made correctly, or the lenses were not fitted correctly. I asked him to get the lenses check at a different optician, and to also try an OD for his eye exams. It is no wonder that you are in my killfile, and you should be in everyone's killfile. > Since I don't work in the optical industry, it is not even remotely > possible that I have any marketing agenda. Polycarb, with an abbe value of > 30, has the worst optics as any other lens that is generally dispensed in > the US. That is a fact. It sounds like a distortion, every time you say it. Most people wearing -250 can't tell a difference in image quality between poly, Trivex or CR-39. What makes it "worst?" What are these other abberrations you mentioned, besides chromatic dispersion? I didn't hear your answer. > It is no wonder that you are in my killfile Suits me. -MT > It sounds like a distortion, every time you say it. > [quoted text clipped - 9 lines] > > -MT It is called transverse chromatic aberration (TCA), and it affects off-axis vision. Robert Martellaro described in an earlier post. TCA and low abbe value may not be noticeable in a polycarb with -2.50 Rx (I never said they were) but polycarb is "measurably" worse than other almost all other lens materials. The point was that Trivex is better optically than polycarb, so the problems the OP had with Trivex are not related to low abbe value or TCA problems that are sometimes common in polycarb. The Trivex problems were most likely related to something else besides the material itself. > >> Calling polycarbonate the worst possible material suggests you have a > >> marketing agenda. [quoted text clipped - 19 lines] > see that your post above is included on the response of the OP, so I will > respond. Wow. You KILLFILED Mike Tyner?? Does ANYBODY get through your killfile?? > Wow. You KILLFILED Mike Tyner?? > > Does ANYBODY get through your killfile?? He must have responded quite often to the quacks for me to killfile him (or he is one of the quacks, I don't recall). This was at least a year ago. > Should this be done outside with real distance? I'm guessing this is > only a preliminary means to make a judgement and that true lense > measurements are needed. (??) The cover test can be a pretty sensitive measure with nothing more than your hand and a target 10 feet away. The best targets are a small, dark spot or letter or something on a relatively plain background. But your results indicate there's no major misplacement of the optical centers. > As far as I can tell both the Trivex and high index lenses have been > crystal clear to me. No blurring, no waves, and causing no headaches. Then it's not so likely an optical problem. > The discomfort with the Trivex started (as I described) like the way I > remember dirty contacts to feel (from 20 yrs. ago) - kind of > itchy/irritating. Aha. Optical problems don't cause itching or redness. Allergies do. So I'd venture you might have an allergic reaction. Allergies to the acrylics are rare, but the coatings often cause allergic reactions. If your lids are puffy, that clenches it, but they may not be. > Both lense types cause an ache in my eyeballs (feels > like the schlera area) - particularly on the inner sides adjacent to my > nose and sometimes towards the bottoms. Also possible to react to nosepads, or where frames come in contact with the face. Whatever the specific cause, itching and redness are pretty rare in problems that are purely optical. -MT I don't get an itchy feeling like an allergy. It's more of a strain/annoyance in the areas I indicated. There is no redness. That happened the 1st time I wore the trivex, more in the left eye. No visible reactions like puffy lids. > > Should this be done outside with real distance? I'm guessing this is > > only a preliminary means to make a judgement and that true lense [quoted text clipped - 31 lines] > > -MT > Every polycarb that I have seen has an abbe value of 30. Where did you see > 35? It's a typo. I must have copied it wrong from my notes. 30 is correct. >From my limited experience (n=1, and that was enough!), I would have to agree with those who feel that polycarb has lousy optics. The first pair of glasses I got (+1.75, +1.25) were polycarbonate. I was immediately startled and disturbed by the purple and yellow halos I saw everywhere except when looking straight ahead through a 1/4" high area in the middle of the lens. There was nothing subtle about this. In birding only the poorest quality binoculars exhibit this, and you avoid them. So unless something really radical happens to my prescription, I don't plan to try any high-index plastics, as it seems that CR-39 is optically better in every way. However, it's possible that none of this is related to the problems described by the original poster. cheers, LD >> Mark, thank you for the detailed explanation. The moment I put on the >> Trivex in the store I felt discomfort, particularly in my left eye. [quoted text clipped - 3 lines] >> like an irritation the way I remember dirty contacts to feel. Possibly, >> there was a little more tearing too. Those are possibly asthenopic symptoms that may be related to improper optics. >I very much doubt your problem has anything to do with the Trivex lens >material, if that truly is what you received. Ditto. Look, he's wearing poly in his sun Rx without symptoms right? That tells me he's not sensitive to changes in material, ocular, and base curves. There's something wrong with this lens or lenses. >The number of errors in grinding lenses to the correct power and fitting >lenses (for proper placement in the frame so it is optically centered) is >much higher than you would suspect. Yup. Not to mention lenses that are reversed eye for eye. You should see all the crappy glasses I run into that are made by clerks calling themselves opticians and from labs that produce incredibly bad optics with sloppy fit and finish. Robert Martellaro ~~~~~~~~~~~~~~~~~~ Optician/Owner Roberts Optical Wauwatosa Wi. ~~~~~~~~~~~~~~~~~~ "An expert is a person who has made all the mistakes that can be made in a very narrow field." - Niels Bohr It was hard to get a useful definition of Asthenopia until I found the one at: http://en.wikipedia.org/wiki/Eye_strain Yes! Yes! That's a broad definition of what I'm experiencing - particularly to what I believe is the ciliary muscle. I'm headed off to the opthomologist's optician later to see what she can determine from the glasses. I'll update here later... Thank you all again! > >> Mark, thank you for the detailed explanation. The moment I put on the > >> Trivex in the store I felt discomfort, particularly in my left eye. [quoted text clipped - 30 lines] > "An expert is a person who has made all the mistakes that can be made in a very narrow field." > - Niels Bohr > It was hard to get a useful definition of Asthenopia until I found the > one at: http://en.wikipedia.org/wiki/Eye_strain [quoted text clipped - 6 lines] > > Thank you all again! I don't know anything about anything, but ... I'd get a good cyclopegic exam (to figure out whether your -2.50 is right, and to have your Rx checked AT NEAR) AND have them take a CLOSE look at your eye alignment, both at distance AND at near. Some of what you describe could even be accommodative esotropia or a near-point esophoria. In other words, if your eyes aren't working together properly, then -- with minus lenses on -- you could have additional symptoms, especially at near. When you pinpoint the ciliaries in your description, then you MAY be describing an accommodative dysfunction which could be organic OR could be a problem with the prescription. You may need something as simple as bifocals with a slight modification to the Rx. Do let us know what you learn at today's appointment, huh? Good luck! Neil First, no issues wearing my old lenses so I would rule out my eyes being an Asthenopia cause. I saw the the opthomologist's optician. First and foremost she measured my PD AND that of my old glasses. Both 61. New "1.60 high index" glasses 58! When I originally went back to the store w/the "Trivex", they measured them and said they were correct (???) based on on-file measurements from 5 years ago. They then ordered these "1.60 high index" lenses. Don't know what PD the Trivex really were... The optician today said that with a -2.50 Rx Trivex and high index are a waste of money and a significant jump up in price. She said that the lenses I presented are NOT high index but regular poly. I asked how she knew that and she said by the sound when she tapped them - that poly has a distinct thud sound. She said weighing them would be the only other method. Does the thud test make sense? Additionally her opinion was that Hoya and Younger make "very expensive (Trivex) lenses" and that I don't need that - just poly. (???) And if I'm downgraded from Trivex, shouldn't I get a small refund? Additionally, the optician today said that the mistake in the PD would cause the eye discomfort exactly where I feel it (towards the nose sides of the sclera) because my eyes are trying to find the (wrong 58PD) optical center. I realize that this is only one second opinion of the actual glasses, but it falls VERY MUCH in line with the underlying opinions given here, particularly by Mark A and Robert Martellaro. That there are often lense manufacture problems and that it sounds like that is my issue. Do I need another exam of the lenses to verify today's findings or is this evidence enough that they are screwed up? At this point I don't want to deal w/the store I bought them from and will have to battle their "no refund" policy with my "no scew-up" policy. Any comments on today's results and the optician's opinions and what lenses I should ultimately get would be appreciated! Thank you very much! > > It was hard to get a useful definition of Asthenopia until I found the > > one at: http://en.wikipedia.org/wiki/Eye_strain [quoted text clipped - 27 lines] > > Neil My $.02 worth is that in a -2.50 trivex is an ideal material. The optics are great, they are 100% UV protected, anti-scratch and about the lightest, strongest, safest material around. They are more than poly (as they should be), but less than 1.60 (there's no reason for you to have 1.6 in a -2.50). The 3mm error in p.d. results in about 0.75 base out prism. Not much, but it could be a problem and shouldn't be there. The "thud" test to me is more like a "ting" sound with poly. I sure wish there were a clinical instrument that could analyze the index of refraction of an unknown lens. Should be a trivial thing to invent/produce. w.stacy, o.d. >First, no issues wearing my old lenses so I would rule out my eyes >being an Asthenopia cause. [quoted text clipped - 77 lines] > > > First, no issues wearing my old lenses so I would rule out my eyes > being an Asthenopia cause. [quoted text clipped - 37 lines] > > Thank you very much! I realize that you are getting info from your optician, but you should stop using the term "high index". It has no real meaning anymore. Instead, use the actual index of the material such as 1.50, Trivex (1.53), polycarb (1.59), 1.60, 1.67, etc. As you can see, polycarb has almost as high an index as 1.60. But they are completely different materials in terms of optical quality and strength (tensile strength and impact resistance). I believe that you said you needed polycarb because the lenses were in drill mount frames. In that case, if you have a lens that has similar resistance to cracking on drill mount frames as polycarb, but you want better optics, then Trivex is your best choice. It is up to you whether you want to pay for the additional cost. BTW, just about any optical shop will examine your current lenses for you and tell you what Rx (power) they are made to. They will do this without obligation to purchase at that store. If you really feel guilty, then go to Wal-mart optical and have them do it. The PD measurement taken of me was done with the little scale across my nose. It would seem that there's room for error with that. Is there a better way? And PD is measured from what to what? > First, no issues wearing my old lenses so I would rule out my eyes > being an Asthenopia cause. [quoted text clipped - 69 lines] > > > > Neil Your mileage may vary. I can measure with a mm rule to within 1 mm accuracy, but I'm good at it, and am very careful about parallactic error in my technique. More accuracy can be had with a pupillometer, but those are subject to other errors (mostly patient looking in the wrong direction). Pupillometers are necessary when monocular p.d.s are needed for progressive lenses (like no-line multifocals). The idea is to get the distance between the two optical axes, or more crudely the distance between the centers of the pupils. For monocular p.d.s, it's from the optcal axis to the center of the nose, one for each eye. w.stacy, o.d. >The PD measurement taken of me was done with the little scale across my >nose. It would seem that there's room for error with that. Is there a >better way? And PD is measured from what to what? > > Through this whole discussion, can no one simply go back and say CR-39 plastic is superior to many of these newer materials? At -250 his lenses would look just fine in CR39 at minimal center thickness. There are patients that can wear a pair of glasses that are 10mm off on PD and they feel fine, and there are those that get vertigo from a PD off by 1 mm. These people need CR-39. End of story. Repeat after me. It sounds like a duck. It walks like a duck. It smells like a duck. I think its a.....CR-39 patient!! > Your mileage may vary. I can measure with a mm rule to within 1 mm > accuracy, but I'm good at it, and am very careful about parallactic [quoted text clipped - 13 lines] > > > > > Through this whole discussion, can no one simply go back and say CR-39 > plastic is superior to many of these newer materials? At -250 his [quoted text clipped - 5 lines] > Repeat after me. It sounds like a duck. It walks like a duck. It > smells like a duck. I think its a.....CR-39 patient!! I think it was mentioned that CR-39 (1.50) index is fine for a -2.50. But maybe not end of story. The OP wanted drill mount frames and the optician chose polycarb (mostly) for that reason. CR-39 may be acceptable to some people for drill mounts, but obviously polycarb is superior. That is what leads us to Trivex, which has the strength of polycarb, and much better optics (even though not quite as good as CR-39 in that respect). OK but... the new frames which I'm happy with are Silhouette rimless drilled through the lens. My understanding is that CR39 will break w/that. BTW - eyeglasses.com shows lenses and their prices (http://www.eyeglasses.com/information/services/lenses_price.page). Trivex is not so pricey in comparison to poly, 160, and 1.67 lenses. They don't seem to offer AR for the Trivex. > Through this whole discussion, can no one simply go back and say CR-39 > plastic is superior to many of these newer materials? At -250 his [quoted text clipped - 22 lines] > > > > > > > OK but... the new frames which I'm happy with are Silhouette rimless > drilled through the lens. My understanding is that CR39 will break [quoted text clipped - 4 lines] > Trivex is not so pricey in comparison to poly, 160, and 1.67 lenses. > They don't seem to offer AR for the Trivex. Maybe eyeglasses.com doesn't offer AR on Trivex, but the Hoya optical lab does. OK, this is my final post in this thread (hopefully). Hoya makes SV lenses with Trivex material (which they call Phoenix). Their SV lenses come in standard (Hi-lux spheric) or aspheric (Nulux aspheric) models. Some expert on this forum can advise you on which one to get in light of your previous problems. Here is a description of the differences: "Hi-lux spheric: features a single central radius on the front surface and, depending on the prescription, different radii on the back surface." "Nulux aspheric: the radius leading from the centre of the front surface to its edge becomes longer, and the radii form a purer focal point. This results in less deformation in the periphery of the lens." Hoya SV lenses are available with their factory AR coatings, the best of which is called Super HiVision. This is not the same as HiVision. Ask an optical shop for a price quote on Hoya SV (non-aspheric or aspheric) Phoenix (Trivex) with Super HiVision. Emphasize to them that you want Super HiVision and not regular HiVision AR coating. If you go with these lenses and have an accurate measurement of the your PD and fitting height (make them re-measure), I think you will be very satisfied. If the optician gives you any trouble or claims they cannot get this lens, speak to the Dr. and complain. |
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