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Medical Forum / General / Vision / May 2005Conductive Keratoplasty
Hello My last eyesight test showed I am +4 in my right eye and +6 in the left., and at present wear night and day contact lenses. Does anybody know if I would be suitable for conductive keratoplasty? Thank you  SignaturePam Gasson Pam, No, you would not be an appropriate candidate for Conductive Keratoplasty (CK) for hyperopia (farsighted, longsighted) of this amount. Your possible alternatives would be rather limited. As a general rule, hyperopia is more difficult to correct than myopia (nearsighted, shortsighted). High hyperopia is quite possibly the most challenging refractive error to correct predictably without inducing other problems. The excimer laser assisted surgery techniques LASIK, IntraLASIK, PRK, LASEK, and Epi-LASIK have significant difficulty with hyperopia of this magnitude. I doubt you would find a competent surgeon who would suggest that you would be able to attain plano (no refractive error) with any of these techniques. If you are under age 40 and are able to accommodate (change focus from distant items to near) then you may want to investigate phakic intraocular lenses (P-IOL). In the UK there are several different P-IOLs. Whether or not the physiology of your eye would allow for a P-IOL would need to be closely evaluated. If you are over age 40 and have lost or are losing accommodation due to presbyopia, then Refractive Lens Exchange (RLE) may be something to consider. RLE is essentially cataract surgery for refractive purposes. The natural lens of the eye is removed and an artificial lens of a power to correct your refractive error would be put in its place. Both P-IOL and RLE are rather invasive procedures that require significant skill and detailed evaluation. For details on these issues, see: http://www.usaeyes.org/faq/subjects/hyperopia.htm http://www.usaeyes.org/faq/subjects/ck.htm http://www.usaeyes.org/faq/subjects/piol.htm http://www.usaeyes.org/faq/subjects/rle.htm Glenn Hagele Executive Director USAEyes.org "Consider and Choose With Confidence" Email to glenn dot hagele at usaeyes dot org http://www.USAEyes.org http://www.ComplicatedEyes.org I am not a doctor. Don't bother with CK, or LASIK for that matter. Glenn is correct. Stick with the contact lenses. DrG Thank you both for your replies.I can forget about it now.I am pleased with my Focus Night@Day so will stay with them. Pam >Don't bother with CK, or LASIK for that matter. Glenn is correct. >Stick with the contact lenses. > >DrG SignaturePam Gasson While I am sure they exist, I have never found a person who was happy with the results of their surgical correction of farsightedness. A few of them have been outright miserable. DrG i would agree that refractive surgery on hyperopes if far less successful than myopes, but i think you overstated your case. i can tell you, from working part time in a refractive surgery practice, that i see people every day that are happy with their LASIK correction of farsightedness. especially if the person is +4 and +6! even if their procedure only partially corrects them to +1 their vision is much improved and they are happy because they can see well at distance without glasses. Patients may not realize that the same dioptic number for hyperopia as for myopia does not indicate the same negative effect on vision. A 4.00 D myope is not the same as a 4.00 D hyperope. All to often I am contacted by a hyperopic LASIK patent who says that his friend's prescription was even more than him, but the friend got a better result. Of course, the friend was a myope. Opinion Please: Doctors, it is my opinion that the detrimental functional visual effect of hyperopia is approximately four times that of a myope. Would anyone agree with this ratio? As an example, a 0.50 D hyperope has the same degradation in vision function as a 2.00 D myope. A 3.00 D hyperope has the same degradation in function as a 12.00 D myope. Any discussion would be appreciated. Glenn Hagele Executive Director USAEyes.org "Consider and Choose With Confidence" Email to glenn dot hagele at usaeyes dot org http://www.USAEyes.org http://www.ComplicatedEyes.org I am not a doctor. > Opinion Please: Doctors, it is my opinion that the detrimental > functional visual effect of hyperopia is approximately four times that > of a myope. Would anyone agree with this ratio? No, for several reasons. First, it's apples and oranges to compare disability at near with disability at distance. One can't read and the other can't drive, so for chosen tasks you can say each experiences total disability - 1 to 1, not 4 to 1. And a young 4-D hyperope might experience no symptoms at all. > As an example, a 0.50 D hyperope has the same degradation in vision > function as a 2.00 D myope. Very unlikely. It's more appropriate to equate an 0.50 _myope_ with a +2.00 _hyperope_, sorta the opposite of your ratio. The majority (under 50) have some functioning accommodation to compensate. Myopes can't compensate, except by squinting. -MT > Opinion Please: Doctors, it is my opinion that the detrimental > functional visual effect of hyperopia is approximately four times that > of a myope. Would anyone agree with this ratio? I don't. I agree that hyperopia can cause some serious problems, especially in the moderate to high amounts. But your ratio is artificial, simplistic, and wrong. > As an example, a 0.50 D hyperope has the same degradation in vision > function as a 2.00 D myope. A 3.00 D hyperope has the same > degradation in function as a 12.00 D myope. Hardly. A half diopter hyperope has no significant degradation in vision at all until he/she reaches 40 or 45 years of age, at least. A 2 D. myope is unable to even drive a car without lenses at age 16. Now a 3 D. hyperope is in trouble, but no where near as much as a 12 D. myope. +3 D. needs to be corrected in most cases to prevent amblyopia and other problems, but the person can usually still drive without lenses legally into their 30s. 12 D. of myopia or hyperopia is equally devastating visually, but the myope is far more susceptible to organic damage from his overly large eyes than the equivalent hyperope with his overly small eyes. Having said that, I'd still rather be a little myopic than a little hyperopic, because even at age 61, this myope can read without glasses while his hyperopic wife can't do much of anything without hers. w.stacy, o.d. > Having said that, I'd still rather be a little myopic than a little > hyperopic, because even at age 61, this myope can read without glasses > while his hyperopic wife can't do much of anything without hers. I don't know, I think she could probably smash a watermelon over your head without a lot of difficulty! SignatureCheers, Bev --------------------------------------------------- Don't you just KNOW that there is more than one Sierra Club member who is absolutely sure that the dinosaurs died out because of something humans did? That she could. Seriously, at +3.00 age 60, she's considering clear lens exchanges. Tired of messing with contacts. w.stacy, o.d. >>Having said that, I'd still rather be a little myopic than a little >>hyperopic, because even at age 61, this myope can read without glasses >>while his hyperopic wife can't do much of anything without hers. > > I don't know, I think she could probably smash a watermelon over your head > without a lot of difficulty! i disagree completely. a 1.00 diopter hyperope is frequently 20/25 at distance and needs reading glasses only. a 1.00 diopter myope is 20/40 to 20/50 at distance and needs glasses to drive. its apples and oranges. your ratio and comparison strongly depends on the patients age since hyperopia is less of a problem for pre-presbyopes. myopia is a problem for people at all ages. Thanks all. This is exactly the kind of input I was seeking. Glenn Hagele Executive Director USAEyes.org "Consider and Choose With Confidence" Email to glenn dot hagele at usaeyes dot org http://www.USAEyes.org http://www.ComplicatedEyes.org I am not a doctor. DrG's top ten reasons not to be hyperopic: 1. Hyperopia is far more likely than myopia to be associated with amblyopia. 2. Hyperopia is far more likely to be associated with strabismus (esotropia). 3. Hyperopia has a stronger association with vision-related learning problems. 4. An adult myope can see clearly at some distance. An adult hyperope cannot see clearly at any distance. The natural reaction to seeing something is to get closer. This only makes things worse for the hyperope. 5. We live in a world that is increasingly dominated by nearpoint activities. This favors myopia and not hyperopia. 6. Hyperopes hate the way their glasses make their eyes look. 7. Hyperopic lenses have more mass. It's all concentrated in the center. 8. Hyperopic eyes tend to be smaller. 9. Hyperopia is a risk factor for glaucoma. 10. Accommodative spasm hurts. DrG Very good. But as a myope, I've got to come to the aid of the hyperopes out there. > DrG's top ten reasons not to be hyperopic: > > 1. Hyperopia is far more likely than myopia to be associated with > amblyopia. Only if the hyperopia is missed in early childhood. > 2. Hyperopia is far more likely to be associated with strabismus > (esotropia). Myopia is far mor likely to be associated with exotropia. > 3. Hyperopia has a stronger association with vision-related learning > problems. I'm not sure that has been definitively proven. > 4. An adult myope can see clearly at some distance. An adult hyperope > cannot see clearly at any distance. The natural reaction to seeing > something is to get closer. This only makes things worse for the > hyperope. Depends on the amounts and age. Lots of +1.00 D. hyperopes see 20/15 in their 20s, even at near. And true, a 3 D. myope can see at 33 cm without his glasses, he' not likely to bother taking his glasses off until he hits 40 years old. > 5. We live in a world that is increasingly dominated by nearpoint > activities. This favors myopia and not hyperopia. Fortunately we have glasses and contacts (and otis). These marvels tend to level the playing field. One example I know very well, my wife is a 3 D. hyperope who reads at least 10x more than this myope. > 6. Hyperopes hate the way their glasses make their eyes look. I greatly prefer the large eye look to the tiny beady eye look you get through particularly strong lenses, but that's me. > 7. Hyperopic lenses have more mass. It's all concentrated in the > center. I'm not so sure that's true. Look at the geometry of a lens. The thickest part of a minus runs all the way around the periphery of the lens, while the thickest part of a plus is only at one point, at the optical center. > 8. Hyperopic eyes tend to be smaller. True, but they look nice and large when they put their glasses on. > 9. Hyperopia is a risk factor for glaucoma. Maybe narrow angle (rare), myopes are at greater risk for other forms of glaucoma (common). > 10. Accommodative spasm hurts. Again, fixed by glasses for hyperopes, but actually CAUSES myopes to get worse. I'll add three more good reason to be hyperopic: You're less likely to have your eyes damamged by LASIK. You're far less likely to get a retinal detachment. When you're 18, you get more dates. w.stacy, o.d. > Very good. But as a myope, I've got to come to the aid of the hyperopes > out there. [quoted text clipped - 5 lines] > > Only if the hyperopia is missed in early childhood. ...and it's missed alot, more often than myopia. > > 2. Hyperopia is far more likely to be associated with strabismus > > (esotropia). > > Myopia is far mor likely to be associated with exotropia. Esotropia is more common by 3:1, according to most studies. > > 3. Hyperopia has a stronger association with vision-related learning > > problems. > > I'm not sure that has been definitively proven. Well, it has been studied by Jerome Rosner at the U of H School of Optometry. > > 4. An adult myope can see clearly at some distance. An adult hyperope > > cannot see clearly at any distance. The natural reaction to seeing [quoted text clipped - 4 lines] > their 20s, even at near. And true, a 3 D. myope can see at 33 cm without > his glasses, he' not likely to bother taking his glasses off until he > hits 40 years old. OK. Let me revise the statement. At some point in life, a hyperope will have trouble seeing at all distances, whereas a myope will always be able to see clearly at some distance. > > 5. We live in a world that is increasingly dominated by nearpoint > > activities. This favors myopia and not hyperopia. > > Fortunately we have glasses and contacts (and otis). These marvels tend > to level the playing field. One example I know very well, my wife is a 3 > D. hyperope who reads at least 10x more than this myope. At least you didn't disagree with the point made. > > 6. Hyperopes hate the way their glasses make their eyes look. > [quoted text clipped - 6 lines] > I'm not so sure that's true. Look at the geometry of a lens. The > thickest part of a minus runs all the way around the periphery of the > lens, while the thickest part of a plus is only at one point, at the > optical center. Yes, but as the lens is edged down to fit the frame, the thicker part gets discarded, whereas the thinner part of the plus lens gets discarded. > > 8. Hyperopic eyes tend to be smaller. > > > True, but they look nice and large when they put their glasses on. Then why do I hear so many hyperopes complain about how large their eyes look behind their eyeglasses? > > 9. Hyperopia is a risk factor for glaucoma. > > > Maybe narrow angle (rare), myopes are at greater risk for other forms of > glaucoma (common). >From the AAO Basic and Clinical Science Course, Section 10, Glaucoma (2000-2001): "Hyperopic eyes are at increased risk of angle closure glaucoma...Whether myopic eyes have increased risk of open angle glaucoma remains a controversial issue." > > 10. Accommodative spasm hurts. > > Again, fixed by glasses for hyperopes, but actually CAUSES myopes to get > worse. Uncorrected hyperopes accommodate more than uncorrected myopes. > I'll add three more good reason to be hyperopic: You're less likely to > have your eyes damamged by LASIK. You're far less likely to get a > retinal detachment. When you're 18, you get more dates. But, you are more likely to have a bad result if you DO get LASIK. I concede one of the other points. Not sure about the dates. DrG >> Very good. But as a myope, I've got to come to the aid of the >hyperopes [quoted text clipped - 106 lines] >But, you are more likely to have a bad result if you DO get LASIK. I >concede one of the other points. Not sure about the dates. I just hate it . . . all around. Myopes looking to switch?? Neil Age 41 Accommodative Spasm, etc., etc.... 8.44 -1.71 89 7.95 -1.92 69 > Then why do I hear so many hyperopes complain about how large their > eyes look behind their eyeglasses? Because they are looking into a mirror and getting twice the magnification that someone else looking at them gets. >Whether myopic eyes have increased risk of open angle > glaucoma remains a controversial issue." maybe, but it's not controversial that myopic eyes are at greater risk for lots more kinds of eye pathology than are hyperopic eyes. > Uncorrected hyperopes accommodate more than uncorrected myopes. Maybe so, maybe no. Lots of myopes read at 12 inches or closer, while lots of hyperopes read at 17 inches or farther. You do the math. > But, you are more likely to have a bad result if you DO get LASIK. I > concede one of the other points. Not sure about the dates. Likewise, you are more likely to get a good result from clear lens exchange if you're hyperopic. Re the dates, it's because you're more likely to be a nerd if you are myopic, and a jock if you're hyperopic. Sigh. I just thought of another risk factor. You're more likely to get annoying suggestions from Otis if you're myopic. w.stacy, o.d. >I just thought of another risk factor. You're more likely to get >annoying suggestions from Otis if you're myopic. Thanks, Bill. I was just starting to get sullen about my high hyperopia. You pulled me right out :-) You're welcome. You reminded me of another one. If you're stranded on a desert island, you can use your glasses to start a fire. Myopes can't. w.stacy,o.d. (btw, if you're anywhere near presbyopia you should consider clear lens exchange. Essentially zero risk for retinal detachment for you, unlike the myopes.) ws >>I just thought of another risk factor. You're more likely to get >>annoying suggestions from Otis if you're myopic. > > Thanks, Bill. I was just starting to get sullen about my high > hyperopia. You pulled me right out :-) >You're welcome. You reminded me of another one. If you're stranded on >a desert island, you can use your glasses to start a fire. Myopes can't. But you know that *huge* insect that invariably exists on the desert isle? I'd rather look at it through a high-minus lens than try to incinerate it with high-plus ;-) >(btw, if you're anywhere near presbyopia you should consider clear lens >exchange. Essentially zero risk for retinal detachment for you, unlike >the myopes.) Scared. 1) No *data* indicating it will end accommodative spasm if it's of refractive etiology. Theoretically, it could make it worse. I don't *believe* the accommodative system ever gives up. I think that the most it does is goes 'dormant.' If it truly gave up, how could presbyopes regain lost accommodation using accommodating IOLs? I just think--if one never had symptoms associated with accommodation--one will never will have symptoms, even with fixed IOLs in place. Doesn't mean the proximity-induced accommodation isn't at play. I'd welcome discussion on this (since it's just my theory).... 2) I have *severely* dry eyes, *barely* managed with punctal cautery * 4 and frequent drops. Cataract surgery (PubMed) tends to decrease TBUT by 2.5s and Schirmer's by 2.5mm, on average. Scared. Very scared. Sigh.... Back to my island, I suppose ;-) > Scared. > > 1) No *data* indicating it will end accommodative spasm if it's of > refractive etiology. Theoretically, it could make it worse. I don't > *believe* the accommodative system ever gives up. I think that the > most it does is goes 'dormant.' I agree, having these non-accommodating iols for 5 months now, I'm pretty sure my ciliary muscles are still working, even though it's not having any effect on the silicone lenses. If it truly gave up, how could > presbyopes regain lost accommodation using accommodating IOLs? They get a little, not much, from lens movement only. I just > think--if one never had symptoms associated with accommodation--one > will never will have symptoms, even with fixed IOLs in place. Doesn't > mean the proximity-induced accommodation isn't at play. I'd welcome > discussion on this (since it's just my theory).... I changed the thread name because it is an interesting topic and might get some play. > 2) I have *severely* dry eyes, *barely* managed with punctal cautery * > 4 and frequent drops. Cataract surgery (PubMed) tends to decrease > TBUT by 2.5s and Schirmer's by 2.5mm, on average. Scared. Very > scared. I believe that in the hands of a very skilled surgeon, this effect can be minimized. It sounds like you have much to gain. What are your numbers? (refraction, age). I mean you'll still have dry eyes, for sure, but the optical advantage is large. One of the advantages of being myopic dr. leukoma forgot, and I just remembered it. High hyperopes have those pesky ring scotomata when they're wearing strong glasses. I bet you'd like to give those up... bill w.stacy, o.d. >> Scared. >> [quoted text clipped - 11 lines] > >They get a little, not much, from lens movement only. But it's those pesky ciliaries flexing the lens, no? I'd like mine to 'take 5.' Atropine b.i.d. was working, but the side effects were unmanageable . . . and it was nibbling away at my corneas :-( >> I just >> think--if one never had symptoms associated with accommodation--one [quoted text clipped - 13 lines] >be minimized. It sounds like you have much to gain. What are your >numbers? (refraction, age). Age: 41. Wavefront Rx: SPH CYL AXIS OD 8.44 -1.71 89 OS 7.95 -1.92 69 >I mean you'll still have dry eyes, for >sure, but the optical advantage is large. One of the advantages of >being myopic dr. leukoma forgot, and I just remembered it. High >hyperopes have those pesky ring scotomata when they're wearing strong >glasses. I bet you'd like to give those up... I still wear the soft toric contacts about 15hrs/day. I do this because: a) Sharper vision, plain and simple. Can wear (any of my dozen pairs of) readers over them, when necessary b) The contacts are full (Atropinized) cycloplegic Rx. For some reason, my eyes will relax a bit for the cl's, but not the specs (so the spec Rx is ~2d less plus) c) Hyperopes accommodate less with cl's than with specs; myopes, the opposite d) cl's allow me to wear my Panoptx total-wraparound sunglasses when outside (and, generally, give me more access to things that ameliorate effects of light, wind, glare, etc.) The only thing I currently *don't* have corrected (it is in my specs) is my exo-. I'm about 6-8d, IIRC . . . which obviously drives additional accommodation.... Can't put that much prism in full-wrap sunglasses, to my knowledge. (I've had three strabismus surgeries. Congenital esotrope). I can *manage* the dry eye now. A material reduction in TBUT or Schirmer's and I'm in trouble. Relief from spasm is a very appealing concept, but it's still an unknown. I still view myself as having much to lose. The walls have moved in on me dramatically over the years, but I'm still creating a life within. Move those walls in too much more, and I'm not sure what would be left.... Risk . . . risk. > But it's those pesky ciliaries flexing the lens, no? Right, or at least that's what they claim. I'd like to see it. I'd like mine to > 'take 5.' Atropine b.i.d. was working, but the side effects were > unmanageable . . . and it was nibbling away at my corneas :-( Strong medicine. Never heard of such a case, but I've often wondered if the ac/a ratio was driven more by the rectus muscles than the other way around (in which case it should be called the a/ac ratio)... > Age: 41. > [quoted text clipped - 3 lines] > OD 8.44 -1.71 89 > OS 7.95 -1.92 69 Perfect candidate for iols, along with maybe a couple of little astigmatism relaxing incisions. You would be giving up a few years of accommodative ability, but sounds like you'd just as soon do that anyway... > I still wear the soft toric contacts about 15hrs/day. I do this > because: > > a) Sharper vision, plain and simple. Can wear (any of my dozen pairs > of) readers over them, when necessary Obviously. Same effect with iols. I'm a bit surprised you can do that with all the dryness. What brand? > b) The contacts are full (Atropinized) cycloplegic Rx. For some > reason, my eyes will relax a bit for the cl's, but not the specs (so > the spec Rx is ~2d less plus) Lends more fuel to my idea that maybe it's your convergence driving the accommodation rather than the other way around. > c) Hyperopes accommodate less with cl's than with specs; myopes, the > opposite Right, due to the effective powers of the lenses at the various distances. > d) cl's allow me to wear my Panoptx total-wraparound sunglasses when > outside (and, generally, give me more access to things that ameliorate > effects of light, wind, glare, etc.) Another nice benefit of iols. > The only thing I currently *don't* have corrected (it is in my specs) > is my exo-. I'm about 6-8d, IIRC . . . which obviously drives > additional accommodation.... Can't put that much prism in full-wrap > sunglasses, to my knowledge. (I've had three strabismus surgeries. > Congenital esotrope). It would be tough. Do you need more or less prism at near than far? > I can *manage* the dry eye now. A material reduction in TBUT or > Schirmer's and I'm in trouble. Relief from spasm is a very appealing > concept, but it's still an unknown. I think you could manage any reduction of tbut, I mean you're probably going to get dryer anyway with age. Lots of things you can use, maybe more often than now, but managable. > I still view myself as having much to lose. The walls have moved in > on me dramatically over the years, but I'm still creating a life > within. Move those walls in too much more, and I'm not sure what > would be left.... > > Risk . . . risk. To me, the advantages far outweigh the risks. The optical gains for you are tremendous (as you already know with the CLs), and you could always wear one of those new silicone CLs as a bandage lens if push came to shove. And of course you'd never have to worry about getting cataracts... w.stacy, o.d. >>Atropine b.i.d. was working, but the side effects were >> unmanageable . . . and it was nibbling away at my corneas :-( > >Strong medicine. Never heard of such a case, but I've often wondered if >the ac/a ratio was driven more by the rectus muscles than the other way >around (in which case it should be called the a/ac ratio)... Interesting. Started with Mydriacyl, 3x/week. When the spasm started to return, we moved me up to nightly. When that wouldn't stave it off, moved to Cyclomydril, then 2x/week Atropine. Finally, I read that Atropine had a bi-phasic half life. The first was only hours after instillation -- about when the symptoms started to return. We then went with the bid routine. >> Age: 41. >> [quoted text clipped - 7 lines] >astigmatism relaxing incisions. You would be giving up a few years of >accommodative ability, but sounds like you'd just as soon do that anyway... Then, of course, there's the question of yet more dryness from the lri's. >> I still wear the soft toric contacts about 15hrs/day. I do this >> because: [quoted text clipped - 4 lines] >Obviously. Same effect with iols. I'm a bit surprised you can do that >with all the dryness. What brand? Can't recall. I'll have to see if I can find out. >> b) The contacts are full (Atropinized) cycloplegic Rx. For some >> reason, my eyes will relax a bit for the cl's, but not the specs (so >> the spec Rx is ~2d less plus) > >Lends more fuel to my idea that maybe it's your convergence driving the >accommodation rather than the other way around. Having watched a movie at my friend's house (60" rear-projection TV. Seated about 8' away) last evening, I tend to agree. Holding 10d must drive significant accommodation. I was whupped when we left. Flat out whupped. >> The only thing I currently *don't* have corrected (it is in my specs) >> is my exo-. I'm about 6-8d, IIRC . . . which obviously drives [quoted text clipped - 3 lines] > >It would be tough. Do you need more or less prism at near than far? Just checked the chart. Looks like it's 10d; 9 at near. >> I can *manage* the dry eye now. A material reduction in TBUT or >> Schirmer's and I'm in trouble. Relief from spasm is a very appealing >> concept, but it's still an unknown. >> >I think you could manage any reduction of tbut, Last two readings were noted, simply, as "< 5s." That's with the full cautery. >I mean you're probably >going to get dryer anyway with age. Then I'll stop aging. There. That was easy ;-) >Lots of things you can use, maybe >more often than now, but managable. Hmm. >> I still view myself as having much to lose. The walls have moved in >> on me dramatically over the years, but I'm still creating a life [quoted text clipped - 7 lines] >wear one of those new silicone CLs as a bandage lens if push came to >shove. And of course you'd never have to worry about getting cataracts... But that addresses solely the sicca component. I already have ciliary hypertonicity and a tremendous propensity to spasm. What if the accommodative spasm just goes nuts and tries its hardest to break these IOL's (by firing and firing and firing) without burning out? So far, I've found nobody who says it *can't* happen, and several who feel it to be a "real possibility." That's the real issue. If I do IOL's -- especially with a 5.5 or 6mm OZ (with my 7mm pupil), and have to go to "emergent" Atropine to break an even more tenacious spasm, I'll have all the same halo (et al) effects that a bad lasik job gives, plus chromatic abberations, photophobia, and corneal munching that come with chronic use of cycloplegia. Nobody can say it's a 1%, 2%, 5%, or 10% risk. I haven't found anybody who knows. That's the fear.... Grateful for the help . . . as always. > Then, of course, there's the question of yet more dryness from the > lri's. Well I experienced a little dryness day 1 post-op, but that was all. Not sure if that sensation came from the 3mm cataract incision or the relaxing incisions, or both. Anyway, all incisions are peripheral, where dryness irritataion would be less noticeable than centrally. > Having watched a movie at my friend's house (60" rear-projection TV. > Seated about 8' away) last evening, I tend to agree. Holding 10d must > drive significant accommodation. I was whupped when we left. Flat > out whupped. Have you tried doing anything with one eye patched? That would completely eliminate any convergence issues. Worth a try. > Just checked the chart. Looks like it's 10d; 9 at near. Experiment with a patch at far and at near. Could be revealing as to what's driving what. Then I'll stop aging. There. That was easy ;-) Right on. > But that addresses solely the sicca component. I already have ciliary > hypertonicity and a tremendous propensity to spasm. What if the > accommodative spasm just goes nuts and tries its hardest to break > these IOL's (by firing and firing and firing) without burning out? So > far, I've found nobody who says it *can't* happen, and several who > feel it to be a "real possibility." Well I don't think the ciliary muscle is physically capable of breaking an iol. Not that it might not be strong enough, but that it is just too large in diameter when fully contracted to ever "squeeze" the iol. Remember, the muscle is connected to the lens capsule with suspensory zonules, not directly physically in contact with it. > That's the real issue. If I do IOL's -- especially with a 5.5 or 6mm > OZ (with my 7mm pupil), and have to go to "emergent" Atropine to break > an even more tenacious spasm, I'll have all the same halo (et al) > effects that a bad lasik job gives, plus chromatic abberations, > photophobia, and corneal munching that come with chronic use of > cycloplegia. Actually, I think it's common for pupils to end up smaller post iol implantation. Not sure why this is, but mine seem smaller now, est. from 6 down to 5, maybe 5 to 4 or so; I'll check. > Nobody can say it's a 1%, 2%, 5%, or 10% risk. I haven't found > anybody who knows. Right, everything would be a guesstimate. You're the one who has to pull the handle, or press the button. Let me know what the patch does or doesn't do, and try it on each eye. w.stacy, o.d. >Experiment with a patch at far and at near. Could be revealing as to >what's driving what. It's been a while. I think you're right: it's time. Drug store, here I come. I hope they come in designer colors, bullseyes, or simple spirals these days. Basic black . . . I don't know.... >> But that addresses solely the sicca component. I already have ciliary >> hypertonicity and a tremendous propensity to spasm. What if the [quoted text clipped - 6 lines] >an iol. Not that it might not be strong enough, but that it is just too >large in diameter when fully contracted to ever "squeeze" the iol. Sorry. Bad metaphor on my part. What I should have said is this: given that there is no *known* neurologic etiology to *my* ciliary spasm (and given my high refractive error), my assumption is that it's all refractive in nature. My accommodative system has worked itself stupid trying to overcome blur (or near-reflex stimuli). In the process, the ciliaries have hypertrophied, exacerbating the whole thing. That's all getting worse as I move into presbyopia (now). The hypertonicity seems to be increasing. I'm more symptomatic, even without doing near work, than ever before. I believe that it's the accommodative system responding to the inchoate lenticular inelasticity. My focusing system is saying, "What? You don't want to flex any more?? What if I just double the ciliary push, then? How do you like that" It's ugly. Ciliary petulance and machismo at its worst. Hasten that process--by giving it something that it *can't* alter (a monofocal IOL) and there's a couple ways it could go: 1) It could "burn out" and give up. Case closed. 2) It could work and work and work and work, increasing my dizziness, pain, and fatigue, without ever burning out. Ouch. Nobody's ever done it . . . except one case where an MVA left a young man with spasm from neurologic issues. http://snipurl.com/f1zh His resolved totally. His ciliaries, though, had no evidence of hypertrophy. Mine are tenacious little buggers. How does that translate? Unknown. >> That's the real issue. If I do IOL's -- especially with a 5.5 or 6mm >> OZ (with my 7mm pupil), and have to go to "emergent" Atropine to break [quoted text clipped - 6 lines] >implantation. Not sure why this is, but mine seem smaller now, est. >from 6 down to 5, maybe 5 to 4 or so; I'll check. Also interesting. Wonder why that is.... >> Nobody can say it's a 1%, 2%, 5%, or 10% risk. I haven't found >> anybody who knows. > >Right, everything would be a guesstimate. You're the one who has to >pull the handle, or press the button. Yup. And -- after three strabismus surgeries and years of involvement in all of this -- I'm a bit trigger-shy. >Let me know what the patch does or doesn't do, >and try it on each eye. Totally benign and diagnostic idea. I shall. Thanks again. Did I mention that it's nice to have you back? ;-) > It's been a while. I think you're right: it's time. Drug store, here > I come. I hope they come in designer colors, bullseyes, or simple > spirals these days. Basic black . . . I don't know.... Hell, forget the drug store. Take a roll of electrician's tape and black out that mother. I'm on a roll tonight... w.stacy, o.d. Interesting about pupil size post-IOL implantation. Mine is larger than my un-operated eye - sometimes by a large margin, sometimes small, sometimes none at all. Since my eyes are a light blue, the difference is quite noticable. I didn't understand until after it was explained to me that the surgeon goes thru the pupil. I thought the 'entrance' was at the edge of the iris. IS there any explanation for the larger pupil size? Karen > > Then why do I hear so many hyperopes complain about how large their > > eyes look behind their eyeglasses? > > Because they are looking into a mirror and getting twice the > magnification that someone else looking at them gets. But, then everything is magnified, including the head, so that gets cancelled out. > >Whether myopic eyes have increased risk of open angle > > glaucoma remains a controversial issue." > > maybe, but it's not controversial that myopic eyes are at greater risk > for lots more kinds of eye pathology than are hyperopic eyes. Like myopic peripheral retinal degeneration and retinal detachment? OK. I concede that. > > Uncorrected hyperopes accommodate more than uncorrected myopes. > > Maybe so, maybe no. Lots of myopes read at 12 inches or closer, while > lots of hyperopes read at 17 inches or farther. You do the math. Simple. A 2.50 D uncorrected hyperope has to accommodate 5 diopters at 16 inches, whereas a 2.50 D uncorrected myope has to accommodate zero diopters at 16 inches, more or less. > > But, you are more likely to have a bad result if you DO get LASIK. I > > concede one of the other points. Not sure about the dates. > > Likewise, you are more likely to get a good result from clear lens > exchange if you're hyperopic. Yes, but a clear lens exchange is real surgery. > Re the dates, it's because you're more likely to be a nerd if you are > myopic, and a jock if you're hyperopic. Sigh. > > I just thought of another risk factor. You're more likely to get > annoying suggestions from Otis if you're myopic. Well, that certainly trumps everything. A myope does have to wear a poison minus lens, while a hyperope gets the benefit of the plus lens with magical healing properties. DrG >> 7. Hyperopic lenses have more mass. It's all concentrated in the >> center. [quoted text clipped - 3 lines] >lens, while the thickest part of a plus is only at one point, at the >optical center. In low powers minus lenses are about 20% lighter in weight than plus lenses, in higher powers minus are up to 50% lighter. Cr39 using best form base curves. 60mm diameter -1.00DS weighs 8.53g and 10.57g in plus 60mm diameter -3.00DS weighs 10.13g and 15.3g in plus 60mm diameter -7.00DS weighs 13.82g and 26.1g in plus Aspheric designs level the playing field substantially, but the advantage is still towards minus powers. 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 Ok but before I yield on this one, what were the center and edge thickness of these lenses? I'm assuming you actually weighed some uncut stock lenses. w.stacy, o.d. > In low powers minus lenses are about 20% lighter in weight than plus lenses, in > higher powers minus are up to 50% lighter. [quoted text clipped - 9 lines] > Aspheric designs level the playing field substantially, but the advantage is > still towards minus powers. >Ok but before I yield on this one, what were the center and edge >thickness of these lenses? I'm assuming you actually weighed some uncut [quoted text clipped - 15 lines] >> Aspheric designs level the playing field substantially, but the advantage is >> still towards minus powers. 2mm for both. My optical program did the work. The minus and low to medium plus should be accurate but the high plus is inflated. Robert 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 >>Ok but before I yield on this one, what were the center and edge >>thickness of these lenses? I'm assuming you actually weighed some uncut [quoted text clipped - 4 lines] > 2mm for both. My optical program did the work. The minus and low to medium plus > should be accurate but the high plus is inflated. I'm assuming you mean 2mm for the centers on the minus and the edge on the plus? (I asked for edge and center thicknesses on BOTH kinds of lenses) Does the program give the edge thickness for the minus and the center thickness for the plus? Thanks. w.stacy, o.d. >>>Ok but before I yield on this one, what were the center and edge >>>thickness of these lenses? I'm assuming you actually weighed some uncut [quoted text clipped - 7 lines] >I'm assuming you mean 2mm for the centers on the minus and the edge on >the plus? Yes. Robert >Does the program give the edge thickness for the minus and the >center thickness for the plus? Thanks. > >w.stacy, o.d. Bill, I missed this second part to your question, sorry about that. The program (EZFrame DOS aka Alpha-Bytes) calculates edge and center thickness for 6 pre-configured lens materials. Tracing the frame and using surfacing software is more accurate, but I'm usually within 10% or 20%, good enough for showing the differences in weight and thickness. Regards Robert 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 was just questioning the idea that in the case of equivalent + and - lenses, that the plus will necessarily be heavier than the minus. Looking at the geometry of plus and minus lenses, I can't see the reason this would be true. I would expect them to be about the same weight, all else being equal. So I just weighed a - 20 and a + 20 trial lenses and found the + to be indeed slightly heavier (to a mail scale, not all that accurate, but pretty close) and I find that the edge thickness of the plus is 2.0 and the center thickness of the minus is 0.8 mm. I also noticed that the - lens has an angled bevel that removed some of the extra glass that would be there if it were like a "hide-a-bevel". So I still think that if you have the same minimum edge thickness of the plus lens as the center thickness of the minus lens, they will weigh about the same. The only other reason I can think of for any difference in wieght is that the minus lenses have slightly greater curvature (.25 each surface) than the plus, which should make the minus slightly heavier if all other things were equal. Am I missing something? w.stacy, o.d. >>Does the program give the edge thickness for the minus and the >>center thickness for the plus? Thanks. [quoted text clipped - 21 lines] > "An expert is a person who has made all the mistakes that can be made in a very narrow field." > - Niels Bohr >I was just questioning the idea that in the case of equivalent + and - >lenses, that the plus will necessarily be heavier than the minus. [quoted text clipped - 15 lines] > >w.stacy, o.d. Bill, I have no answers yet. I did post this scenario over at Optiboard. The thread is here http://www.optiboard.com/forums/showthread.php?t=12797. My guess is it's related to the meniscus lens shape and the sag depth. Robert I thought this was pretty intuitive, but I'll give it my best shot. Represent a simple plus lens as a hemisphere with radius R. Calculate the volume according to the formula 2/3 pi times the radius cubed. Represent a simple minus lens as a cylinder containing the same hemisphere as above, where the height of the cylinder is the same as R, and the area of the base is represented by pi times the radius squared. The volume of the cylinder is pi*R^2*h or pi*R^3. Subtracting the volume of the sphere from the volume of the cylinder gives the volume of the simple minus lens with a CT of zero. Compare this to the volume of the simple plus lens with ET of zero. If I use 2 as the value of R in the example, I come up with 16.75 for the volume of the hemisphere = plus lens, and I come up with 25.12-16.75 = 8.37 for the volume of the minus lens. Please check my math. DrG You're math is correct for thick lenses with infinitely thin center (minus) and edge (plus). I think it doesn't hold up for relatively thin meniscus lenses as are found in opthalmic optics, where real center thicknesses and edge thickness come into play, and where lens volumes would be better represented by intersections of spheres and cylinders of different radii. But of course then the math gets a bit more hairy. Actual weighing of 36 mm trial lenses (+20 biconvex and -20 biconcave) of the same diameter yielded approximately the same weight. w.stacy, o.d. > I thought this was pretty intuitive, but I'll give it my best shot. > Represent a simple plus lens as a hemisphere with radius R. Calculate [quoted text clipped - 15 lines] > > DrG I think it does. But, then, this wasn't meant to be an exercise in trying to find the exception to the rule. I think it started out as somewhat of a satire. DrG I think you're right about the satire. It actually was an extension of the myopia good, hyperopia bad thread. It's been fun... w.stacy, o.d. > I think it does. But, then, this wasn't meant to be an exercise in > trying to find the exception to the rule. I think it started out as > somewhat of a satire. > > DrG >Actual weighing of 36 mm trial lenses (+20 biconvex and -20 biconcave) >of the same diameter yielded approximately the same weight. Confirmed by Darryl Meister at Optiboard. The math is convincing. Plus lenses will be heavier than minus lenses in real life due the rectangular shape typical with todays frames. Robert Martellaro ~~~~~~~~~~~~~~~~~~ Optician/Owner Roberts Optical robopt@execpc.com ~~~~~~~~~~~~~~~~~~ "Science is a way of trying not to fool yourself." - Richard Feynman As I said, I am sure they exist, and I have heard they exist. I just don't know of any personally. I don't work in a refractive surgery practice, but I certainly know what it is like. You are doing your level best to produce the best outcome, and the patient does their level best to accept the outcome they get. I don't want to get into a major debate here, but I think that there have been some interesting examples posted here recently which illustrate various levels of satisfaction and how patients deal with the artifacts induced by their surgeries. They tend to accept the 50% of the good and learn to deal with the rest. Human nature. DrG Agreed, unless you are presbyopic. In which case clear lens exchange is an option, but only if you are less than thrilled with CL wearing. w.stacy, o.d. > Thank you both for your replies.I can forget about > it now.I am pleased with my Focus Night@Day so will [quoted text clipped - 5 lines] >> >> DrG
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