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Medical Forum / General / Vision / May 2005A little survey about halo in LASIK
I don't know if this is going to get reliable results, but I'll try anyway. I do hope that there will be many truthful and accurate answers. If you had LASIK (or other refractive surgery, but mention about it if it's other than LASIK), you are most welcome to participate in this survey. This is just for informative purposes. 1. How long since you had the (first) surgery? 2. Do you see distortion of any kind, in daylight or in dark? If you answer No, you can stop the survey here, but add a comment about your vision (be critical, show that you do pay attention to visual quality). 3. Do you see disturbing starburst around small/distant lamps at dark? 4. Do you see disturbing halos around bigger/closer lamps at dark? 5. Does the starburst/halo size around lamps change when the pupil size changes? If yes, does the halo reduce to zero or practically almost zero (you can test this for example by looking out a window at night and then constricting the pupils by the use light, eg. flash light)? 6. Has your starburst/halo size or brightness changed after surgery? If yes, please tell how did you measure this (looking at the same lamps month after month from the same spot can be a good test). 7. Do you see a less blurred image if you look through "finger binoculars"? Roll your index fingers and look through the small holes formed. Look at something in room illumination with high contrast, for example a black poster with white text or a white object on black background. 8. Do you have difficulties recognizing faces if the person is standing in front of a bright window -- or do you see everything more or less foggy in room illumination? 9. Your happiness about the result (0-100%), where - 100% = aquity is 20/20 or better, there are no side-effects and any distortion is totally non-disturbing - 50% = some disturbing side-effects, you don't have to worry about glasses anymore, but the vision is far from perfect - 0% = major difficulties at reading and recognizing faces, driving a car at dark is hazardous (or other complications). 10. Your pre-operative prescription, dilated pupil size, perfect correction optical zone size and transition zone size (if you know them). And your age, if you wish. X. If you have something else to comment about your vision, please add it here. Thank you very much for your time and effort! Here are my own responses to the survey. 1. How long since you had the (first) surgery? 3 months. 2. Do you see distortion of any kind, in daylight or in dark? Yes, in dark. Bright daylight is better than pre-op with spectacles. 3. Do you see disturbing starburst around small/distant lamps at dark? Yes. 4. Do you see disturbing halos around bigger/closer lamps at dark? Yes. 5. Does the starburst/halo size around lamps change when the pupil size changes? Yes. It reduces to almost zero when the pupil is about 5.0mm or so. The maximum starburst diameter is quite big and it's very bright too (covering cars behind it etc.). 6. Has your starburst/halo size or brightness changed after surgery? Not at all (since two days after surgery my vision has remained the same). I've measured my distortions for example by looking out of my room window at two lamps. Their starburst max. diameter is now the same as it was before surgery without glasses (the two starbursts are just touching eachother when they're at maximum). 7. Do you see a less blurred image if you look through "finger binoculars"? Yes, I see a very sharp and stable image by looking that way. 8. Do you have difficulties recognizing faces... Yes. 9. Your happiness about the result (0-100%) 50%. 10. Your pre-operative prescription, dilated pupil size, perfect correction optical zone size and transition zone size (if you know them). And your age, if you wish. -4.75 both eyes (-0.25 astigmatism), 7.66mm (horizontal), 6.0mm and with transition zone about 8.2mm. Age is 26. X. If you have something else to comment about your vision, please add it here. I don't have any severe complications or side-effects other than this starburst/fog problem. I use eye drops very rarely anymore (dryness is not severe anymore). I can't see as near as I could anymore, the limit is about 10cm now. Pauli's survey will undoubtedly be interesting, but is under no circumstances going to be representative of reality. A voluntary survey without any controls in an unmoderated newsgroup is not likely to accurately represent the actual reality of all refractive surgery patients or carry much statistical merit. I guess it is time to post again my.... LURKERS, SEARCHERS, and HAPPY CAMPERS How about a statistical fact: 98% of all pedestrian vs. auto accidents occur when the pedestrian is within the crosswalk. Now a statistical analysis: Crosswalks are the most dangerous place for pedestrians to cross the street. If you conclude by the posts on the refractive surgery related bulletin boards and newsgroups that this industry has nothing but problems, you are making the same mistake as assuming crosswalks are the most dangerous place for a pedestrian. People posting on bulletin boards tend to be one of three kinds of researchers. One group is researching before making a decision about refractive surgery. The information this person needs is readily available if they read enough posts. They may never post a message. These are the Lurkers. BTW, Lurker is not a derogatory term. Another type of group using bulletin boards and newsgroups is looking for answers to unresolved problems. They post very specific items and watch the board closely, looking for someone who also has their problem that may have found relief. These people are dissatisfied with the results of their surgery and may even feel they have been wronged. Often they will post warnings to others who may be unaware of the potential for problems like the ones they suffer. These are the Searchers. The last group using bulletin boards and newsgroups are delighted with their refractive surgery and other than "thanks" don't have much to say. These people may even feel a little guilty about posting their satisfactory results amongst so many people who are experiencing difficulty. These are the Happy Campers. This presents a skewed representation of the refractive surgery public. Our organization has determined from multiple sources that about 3% of refractive surgery patients (all types of surgery, all types of refractive error) have an unresolved complication at six months postop. About 0.5% have a serious complication that requires extensive maintenance or invasive treatment to resolve/maintain. The posts on these boards are almost exactly the opposite - around 97% about problems and around 3% about successes. The information about problems relating to refractive surgery is very important and all possibilities must be considered. It is also important not to draw the wrong conclusion when adding up the quantity of information about problems and the quantity of information about successes. 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. > Pauli's survey will undoubtedly be interesting, but is under no > circumstances going to be representative of reality. A voluntary > survey without any controls in an unmoderated newsgroup is not likely > to accurately represent the actual reality of all refractive surgery > patients or carry much statistical merit. I totally agree with that. > Our organization has determined from multiple sources that about 3% of > refractive surgery patients (all types of surgery, all types of > refractive error) have an unresolved complication at six months > postop. About 0.5% have a serious complication that requires > extensive maintenance or invasive treatment to resolve/maintain. And I disagree with that one. Inherent in your organization's presentation of the numbers are two issues: 1. you have a vested interest in promoting refractive surgery. I will add that unlike some similar groups, you do indeed present both sides of the issues and do so with patient's best interest as a real concern, an admirable quality. 2. It is also well known that refractive surgery patients with less than stellar results, as in Paul's case, are more likely to "hide" their complaints. They do this as a psychological protection against the unresolvable depression or regret they feel having altered their body with negative outcome. That being said, do we really know the actual number of patients that have life-altering issues following refractive surgery? --LB, O..D. Actually, if anything, Glenn reflects a negative view of LASIK. His 3% number needs to be revised and lowered. I don't understand why the anti-lasik people attack him so much. They aren't going to ever get someone else to give a seemingly credible negative view of lasik. His infomration is extensive and right on. but his statistics are skewed, and his personal opinions are off the mark. One way to read his posts is to think of them as the most negative slant you could put on real facts. The opposite of that would be the sleazy marketers who put the most rosy, positive slant on the facts without being blatantly false. >> Pauli's survey will undoubtedly be interesting, but is under no >> circumstances going to be representative of reality. A voluntary [quoted text clipped - 28 lines] > >--LB, O..D. > Actually, if anything, Glenn reflects a negative view of LASIK. His > 3% number needs to be revised and lowered. I disagree. I think the true value is somewhat higher. There are a lot of post lasik people out there who don't complain because they see so much better without lenses than they did without lenses pre-operatively, they feel sheepish even mentioning their little "problems". For example, a common case would be a 4 D. myope. 20/400 unaided before surgery (20/15 with glasses or contacts). Post LASIK: Unaided acuity R 20/20- L 20/25+ Now refracts as plano O.U., and 20/15 is now not possible. So the guy/gal is now able to drive without glasses/contacts, and is by the numbers a success, one of the 97%, right? Wrong. This person will never again see 20/15. He/she won't complain, or if so, will be told that the numbers are great. Better than expected. This person may even believe that they have a great result. Sorry, but I like 20/15, and I like not having to strain to read it. w.stacy, o.d. As I recall, the literature for the VISX Customvue system claims that 90% of their standard lasik patients get 20/20 or better. With their customvue LASIK - 99% get 20/20 or better, and 75% get 20/15 or better. If that's not good enough odds for people, don't have lasik. One thing I don't think you are considering is that in your case, you have the luxury of unlimited eye exams and also the luxury of trying out every contact lens availble to find which ones are best for you.. and you replace them more often than a patient would. I recall that when I wore RGP contacts, I needed a new set. The OD changed brands on me from Hydrocurve 3 to some B&L lenses. The exact same Rx and size in B&L were problematic, so I had them changed to Hydrocurve 3 and they were much better. How many people would be lucky enough to get lenses to work well with their eyes? >> Actually, if anything, Glenn reflects a negative view of LASIK. His >> 3% number needs to be revised and lowered. [quoted text clipped - 28 lines] > >w.stacy, o.d. > As I recall, the literature for the VISX Customvue system claims that > 90% of their standard lasik patients get 20/20 or better. With their > customvue LASIK - 99% get 20/20 or better, and 75% get 20/15 or > better. So you probably believe in fairies, too. Or do you simply believe everything is true as long as it's in writing? Duh! 99% 20/20 is ridiculous. Unless, of course, you achieve the ability to read the 20/20 letter size through the ghosts, haze and higher order aberrations with a little bit of squinting, just the right light level to compensate for the loss of contrast and, of course, one letter at a time. Not real-world sharp and clear 20/20. Fabricated. > I recall that when I wore RGP contacts, I needed a new set. The OD > changed brands on me from Hydrocurve 3 to some B&L lenses. Duh. Hydrocurve is a SOFT LENS, not RGP. We really can trust what YOU write, eh? >The exact > same Rx and size in B&L were problematic, so I had them changed to > Hydrocurve 3 and they were much better. That's why we have dozens of lenses to choose from, not one-size fits all. > How many people would be > lucky enough to get lenses to work well with their eyes? It's not luck. Oh, I'd say 99%----or they wouldn't be wearing them, or could choose another type or none at all and back to specs. Get LASIK, doesn't work out, there's no going back. --LB, O.D. > >> Actually, if anything, Glenn reflects a negative view of LASIK. His > >> 3% number needs to be revised and lowered. [quoted text clipped - 28 lines] > > > >w.stacy, o.d. You scare me Larry.. I hope your not really an OD.. but I fear you are. One crucial thing you failed to mention is that the Snellen 20/20 designation is primarily an opinion of an eye doctor. The combined vision of both eyes is generally better than either eye independently. Although I think the VISX data of 99% or better with 20/20 vision with Customvue is accurate, it should be noted - which I failed to do earlier - that during the time period when that data was taken, Customvue was only done on "ideal" patients which is only about 50% of LASIK candidates. Up until about a year ago, Customvue was not available to the other 50% of more problematic patients (it is now). Your garbage about ghosts and haze and HOA is just that.. garbage. I can promise anybody of moderate to severe myopia that the complications of contacts are much more significant that any LASIK complications. Another naughty thing that LVI does is it does LASIK on patients of very low myopia - if it ain't broke, don't fix it... LVI's criteria to be a patient is to have a pulse and a credit card. I don't know where you went to school, but squinting isn't going to affect ghosts, haze or contrast issues. You got one thing almost right... I made a mistake about the name of the new brand contacts that I had prescribed about 14 years ago. I had BOSTON rigid lenses which worked quite well, then decided to try the Hydrocurve 3 TORIC lenses (hardly a typical soft lens) that were advertised to be great but were worthless. Then the doctor put me in B&L rigid lenses which were not so great.. and finally wound up back in Boston rigid lenses. This brings up another issue.. there are so many brands and types of contact lenses that no doctor can possibly stock even a small fraction of those available. Just about every brand and type of lens has it's own unique characteristics and the same Rx with a diiferent brand or type often has radically different effects. You can go crawl back into your hole Larry. And it's probably a good idea that you don't identify yourself. >> As I recall, the literature for the VISX Customvue system claims that >> 90% of their standard lasik patients get 20/20 or better. With their [quoted text clipped - 63 lines] >> > >> >w.stacy, o.d. What were you smoking today cliffy? Quote "One crucial thing you failed to mention is that the Snellen 20/20 designation is primarily an opinion of an eye doctor." Sorry cliff, 20/20 is the line the patient can read. It is standardized so it is a repeatable measure. QUote: "Your garbage about ghosts and haze and HOA is just that.. garbage. I can promise anybody of moderate to severe myopia that the complications of contacts are much more significant that any LASIK complications" You are an expert making promises now?? Contacts can be removed, Lasik can't. Quote: "I don't know where you went to school, but squinting isn't going to affect ghosts, haze or contrast issues." Yes it will. Reducing pupil size will alleviate off axis aberrations such as ghosting, haze and reduced CS. Quote: " I had BOSTON rigid lenses which worked quite well, then decided to try the Hydrocurve 3 TORIC lenses (hardly a typical soft lens) " Actually a very typical soft lens, crappy design, crappy material, but standard for the time. Quote: " Then the doctor put me in B&L rigid lenses which were not so great.. and finally wound up back in Boston rigid lenses. " Actually, cliff, B&L own Boston (Polymer Technology) and have for years. B&L lenses were made from Boston materials. Quote: " This brings up another issue.. there are so many brands and types of contact lenses that no doctor can possibly stock even a small fraction of those available." This is where a thing called experience comes in. Quote: " And it's probably a good idea that you don't identify yourself. " Just like yourself??? If you are going to flame legitimate optometrists who visit here with your usual vitriol cliff, could you at least get your facts straight. Currently you're bgatting at 0.0 dr grant >And I disagree with that one. Inherent in your organization's >presentation of the numbers are two issues: > >1. you have a vested interest in promoting refractive surgery. There is one very important difference: Our organization has no financial incentive for anyone in particular to have or not to have refractive surgery. The doctors we certify certainly do, but we don't make anything if someone does or does not have surgery with a USAEyes.org certified doctor or anyone else. So long as refractive surgery exists in one form or another, the information and services we provide will be in demand. That said, I'm sure that some of the doctors we have certified would not be so interested if they did not reasonably believe that our certification got them more patients. To be very frank and honest, I'm delighted if someone selects a USAEyes.org certified doctor. That means they are selecting someone who is at least independently evaluated. I'm pretty happy when someone uses our 50 Tough Questions For Your Doctor too. In comparison, the ASCRS LASIK guidelines has a very troubling "less than one percent" complication rate statement. But then ASCRS is an ophthalmology trade organization. >I will >add that unlike some similar groups, you do indeed present both sides of >the issues and do so with patient's best interest as a real concern, an >admirable quality. Thanks for the (very) limited endorsement. I'll graciously accept whatever I can get. 8^) >2. It is also well known that refractive surgery patients with less than >stellar results, as in Paul's case, are more likely to "hide" their [quoted text clipped - 4 lines] >That being said, do we really know the actual number of patients that >have life-altering issues following refractive surgery? I don't think there is much anyone can do about people who don't report their outcomes truthfully. But wouldn't you say that goes both ways? For those who over-report problems as well as those who under-report them. 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. > Thanks for the (very) limited endorsement. I'll graciously accept > whatever I can get. 8^) It's not *that* limited. I really do believe that your replies are well thought out, well written and provide a degree of honest presentation that is, at least in these part, very, very lacking in the RS business. It really bothers me to hear day after day radio ads promoting this or that doctor as the "premier surgeon" "now with blah blah laser that can give you better than 20/20, even better that 20/15!" and you know the rest of BS come-ons. > I don't think there is much anyone can do about people who don't > report their outcomes truthfully. But wouldn't you say that goes both > ways? For those who over-report problems as well as those who > under-report them. Sure. But the real issue for me is people who had RS and live a life of constantly looking for a fix to their problems, or have problems that seriously disrupt the quality of their lives. Or, as for one person I know, loose their job as a direct result of LASIK. But equally important is the problem of potential RS patients having an unrealistic view of what will be. And, of course, the scams and doctors with less than stellar ethics. I'm glad that you are trying to deal with those issues. So thanks for that. Nevertheless, there remains an industry-wide problem and one that causes far too many people to live with a life long (hopefully not!) disability. --LB, OD Thank you Glenn for your good analysis on the message board behaviour. I agree (and I have thought about this before). It is a difficult thing to make accurate statistics, even for an honest doctor who is making statistics of his patients. Most of the patients do not know how to accurately describe or measure their problems (but with proper methods it should and must be possible to make accurate statistics!). With this survey, which I hope even some people could take the time to answer, success rate statistics will not be accurate. But, as you might have guessed, my topmost interest is actually the healing process: is it true or is it a myth. With the information delivered within the questionnaire answers I hope to understand the healing process better. And it would be interesting to find out if new relations of things would occur. But that would require hundreds of answers which is of course utopia. For example, it seems that the older you get, the smaller the scotopic pupil will be - does the age of the patient affect halo occurances? No one has survived long enough post-lasik to know that, Pauli. > No one has survived long enough post-lasik to know that, Pauli. According to this: http://www.opt.uh.edu/research/voi/WavefrontCongress/2004/presentations/27BRADLEY.pdf (page 9), the scotopic pupil would be 0.5mm smaller in 10 years. It should be possible to measure the effect of that. Also that (slightly inconclusive) chart would suggest, that people over 50 years should clearly have lesser large pupil related problems (but of course, many studies suggest that large pupil is not a risk factor in the first place which is the first oddity I'd like to dig into). The odds are that you will have additional changes in your refraction by the age of 50 anyway. Myopes tend to become less "short-sighted" as they get older (pun intended). In your further digging, you will undoubtedly find that many studies DO NOT suggest that pupil size is NOT a risk factor in the first place. The few studies suggest that pupil size is not the only risk factor after 6 months with pupils up to 7.0 mm in diameter. The main criticism of the Schallhorn study -- and others -- is the lack of inclusion of very large pupils in the data. I just dispensed a pair of contact lenses to a patient yesterday. His pre-operative prescription was -8.50, with large pupils. Decentration is slightly superiorly. Patient has slight residual refractive error, including irregular astigmatism. BCVA is 20/25 with spectacles. Corneas are just barely thick enough for an enhancement. Should he have had LASIK? The contact lenses completely eliminate the starbursts, for which he is very happy. I am certain that wavefront would reveal a dramatic reduction in spherical aberration and coma, as it has in other cases. The optical zone on the contact lenses is 8.5, with a 0.8 mm blend zone on either side. Previous lenses with 6.5 mm optical zone did not completely eliminate the starbursts. BTW, post-RS patients are often delighted to find that contact lenses after LASIK aren't nearly so uncomfortable as they anticipated. This is due to the relatively large size of the lenses as well as post-operative corneal hypoesthesia. DrG You may be guilty of doing what many people have done, and that is to interpret the findings of Schallhorn et al to say that pupil size is not a risk factor. That is not the findings of these studies. The studies by Schallhorn and several that have followed have shown that pupil size alone is not a reliable predictor of night vision problems after refractive surgery. The distance between "not reliable predictor" and "not a risk factor" can be measured in light years. What Schallhorn affirmed, and nearly every knowledgeable observer already understood, was that night vision problems are multifactorial and are not only caused by an imbalance in the optical ablation size and the naturally dilated pupil size. Several other factors are involved, including amount of refractive error to be changed, depth of ablation, percentage of cornea ablated, angle of transition zone, and undoubtedly much more. Observers have always known that some people with large pupils and small optical ablation zones don't get halos. Schallhorn's study affirmed this. Pupil size is important, even if it pupil size alone is not a reliable predictor of night vision problems. See http://www.usaeyes.org/faq/subjects/lasik_pupil_size.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. > You may be guilty of doing what many people have done, and that is to > interpret the findings of Schallhorn et al to say that pupil size is > not a risk factor. That is not the findings of these studies. The finding of this study http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=1 4711706&dopt=Abstract is that "pupil size was not a major risk factor of NVCs throught the first postoperative year". > What Schallhorn affirmed, and nearly every knowledgeable observer > already understood, was that night vision problems are multifactorial > and are not only caused by an imbalance in the optical ablation size > and the naturally dilated pupil size. What I'd like to add here is that I think that a patient's NVCs could probably be classified and that transition zone (or non-ablated zone) induced NVC could be measured as it's own phenomenon. Larger pupil does unmask more aberrations than just the transition zone problem, but I don't think it strenghtens the aberrations in the central zone, it just exposes more non-perfect surface and that reduces the quality. > Several other factors are involved, including amount of refractive > error to be changed, depth of ablation, percentage of cornea > ablated, angle of transition zone, and undoubtedly much more. Perfect correction ablation diameter, prolate, oblate, "angle of transition zone"... Why are those things so controversial. I realize that because of the limited amout of stroma to be ablated the optimal, patient-dependent ablation pattern has to be mathematically calculated and can not be perfect. And there are different mathematical optimization algorithms. But isn't the angle of transition zone very unambiguous. If it is mathematically refracting elsewhere than the perfect correction zone is refracting, then that's what it will do. Note that I'm NOT saying that the transition zone is the only cause for NVC. Probably even the best human eye sees certain kind of starburst/halo on extremely bright objects (even without the squinting induced effect). Pauli. Don't believe everything you read in an abstract. If somebody concludes that pupil size is not significant, read the entire paper. Recently, I quoted the conclusions of a study involving Intacs and keratoconus. The study used a sample size of 13. One out of the thirteen resulted in a failure, and yet the study concluded that the treatment was not only efficacious, but safe. That is statistical insanity. I also read a study, published in The Lancet in 1999, involving thousands of patients wearing contact lenses. The study found that 1/500 people who slept in their lenses developed infectious keratitis per year using old technology. OK, that's not good, but of those, less than 15% suffered any permanent detrimental effects to their vision. Yet, the study concluded that sleeping in lenses is unsafe. That is also statistical insanity. I am seeing more and more patients taking their refractive surgeons to court over halos and starbursts. Stupid, stupid, stupid. DrG Even if only because of cross-posting of multiple newsgroups, it is nice to see you over here at alt.lasik-eyes, DrG. 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. I'll make sure to be more careful the next time. I found that by going into preview mode, then back to edit, I can eliminate the cross-posting. DrG I use FreeAgent as my newsgroup reader. Whenever I respond to a cross-posted item it brings up a dialog box and asks if I want to post in one or all newsgroups. It is not convenient to notice when something is cross posted in the normal day-to-day of things. 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. > I also read a study, published in The Lancet in 1999, involving > thousands of patients wearing contact lenses. The study found that [quoted text clipped - 3 lines] > Yet, the study concluded that sleeping in lenses is unsafe. That is > also statistical insanity. Well, it may not be statistical insanity if 0% of those who don't sleep in their lenses develop "permanent detrimental effects", while 15% do. I call that 100% for those who do suffer such. I don't think the conclusion was that far off base. When is the last time you saw "permanent detrimental effects" happen to a patient who takes their lenses out every night???? w.stacy, o.d. (who has quite a few patients sleeping in lenses, but still worries about them, a lot!!!, ...) "Dr. Leukoma" <drg@leukoma.com> wrote in news:1116379532.176234.124910 @z14g2000cwz.googlegroups.com: > I am seeing more and more patients taking their refractive surgeons to > court over halos and starbursts. Stupid, stupid, stupid. > > DrG Unless, of course, for some reason the patients were not made aware preoperatively of such risks. At least in the medical research world, being handed a consent form to sign does not constitute proper informed consent. Scott >> I am seeing more and more patients taking their refractive surgeons to >> court over halos and starbursts. Stupid, stupid, stupid. [quoted text clipped - 3 lines] >being handed a consent form to sign does not constitute proper informed >consent. True enough, of course, but I cannot, in my wildest dreams, imagine going forward with a refractive surgery (as a patient) without having done at least some cursory research on my own. . . . and yet I know that people do it all the time . . . . Some surgeons continue to disregard pupil size. That's the stupid part. Even if they do appreciate the risk from the patient's perspective, they clearly don't appreciate the risk to themselves. DrG Ok. I'll go back to the question of how is it possible that some patients with very large pupils have no starburst/halo. There has to be studies about this. Or is it so, that nobody has studied this? Extensive scanning of the eye of patients like that should be done with the best equipment there is. What are considered the most advanced scanning devices in the world and where are they located? I'll just put here my current view of typical starburst/halo/glare problem in a LASIK treated eye. This is just speculation and mostly can probably not be verified true or false with today's methods. Please correct obvious mistakes and add what is missing. Typically, a patient with no severe complications like under-correction, severe misplacement of the flap, epithelial ingrowth or very bad topography will still very likely have night vision problems at least within first year post-op, especially if the scotopic pupil size is more than the perfect correction ablation zone. A patient with a large pupil typically has night vision problems that can be divided into two categories: 1) severe, pupil size dependent distortion and 2) other, mild distortion not strongly related to pupil size. 1) Typical starburst (severe and disturbing) This will manifest as halo when the lamps (or other bright light sources) are big or close enough. Also this will cause strong blur around bright objects on dark background (which means also glare and so called loss of contrast sensitivity). This is caused mostly by the simple fact that the transition zone (and the non-ablated peripheral area) is not refracting the light in the same place as the optically fine central area. Possible explanations for healing: - peripheral growth of stroma and/or epithelium fixing the refractive error in the transition zone - brain adapting to dilate pupils to less than maximum (reducing scotopic pupil size) 2) Typical other distortion (it is assumed there is no severe HOA) This will be seen as faint (compared to the starburst effect) halo or texture around lamps. The radius of the halo is much greater than the starburst radius. The pupil size does not essentially change the effect. Possible causes: - flap interface irregularity and microfolds - Bowman's cracks - misaligned lamellar fibers in stroma (a result of microkeratome) - irregular topography Possible explanations for healing: - cellular rearrangement and smoothing >Ok. I'll go back to the question of how is it possible that some patients >with very large pupils have no starburst/halo. Pauli, if you or I could answer that question, we would become heroes in the refractive surgery industry and the savior of many of patients from misery. 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. I don't think the answer is that difficult. I am willing to step up to the plate if you will provide me with the complete records of those individuals. If we know the "why," then it should not be too difficult to figure out the "why not." Thanks for your participation, Pauli. But looking at yourself in the mirror has its limits. DrG Whoops. I see that in my haste I cross-posted again. Sorry to have offended you folks over on the alt.group. DrG I'm sure they can handle the rejection. 8^) 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, I am absolutely positive that some data mining would come up with the formula. Unfortunately, I only have outcomes info, and not preoperative information. It has been over a years since Schallhorn's study. I would be astonished if there are not one or two groups working on this. Unfortunately, you and I are out of the loop. 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. Well, I'm out of the loop, anyway. 8^) 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. Oh, but you could be very much in the loop. Wouldn't that be nice? DrG > Ok. I'll go back to the question of how is it possible that some patients > with very large pupils have no starburst/halo. There has to be studies about > this. Or is it so, that nobody has studied this? Extensive scanning of the > eye of patients like that should be done with the best equipment there is. Probably a good idea, but the reality is that sarburst/halo is a subjective symptom, not an objective sign. Maybe it could be quantified to a degree by instrumentation, but the fact remains that some people just don't notice it and others do. And to a hugely varying degree of distress. It's like pain. How can you quantify it objectively, when one person jumps out of the chair and screams bloody murder from the same needle stick that causes the next to yawn and ask "so what's up doc?". w.stacy, o.d. Hmmm. I'm sure you're not saying that "it's all in your head," but it kind of sounds that way. I think we all begin our examinations with the patient's chief complaint, and then see if we can come up with an objective correlate. What about headaches? Similar conundrum. If a patient comes to me and complains of halos and starbursts following LASIK, I expect to find some sort of pupil/ablation zone mismatch -- either symmetrical or asymmetrical. Then, when you artificially extend the ablation zone with a large diameter contact lens, the artifacts disappear. If you suffered from constant tinnitus, you would probably learn to tune it out, but you would probably notice if one day you awakened and it wasn't there. If one researches the abstracts, one finds that similar conclusions regarding optical zone/pupillary mismatch have been made, except that the findings also include another variable, which is the pre-surgical level of refractive error. One study blatantly states that their conclusions that pupil size alone is not a good predictor of NVD after 6 months also includes the caveat "for pupils up to 7.0 mm in diameter." The same shortcoming exists with the Schallhorn study. At some diameter of pupil, there is probably a more direct relationship. For example, one patient had a pre-operative prescription of -1.75. The ablation zone appeared to be quite large, except that it was decentered superiorly, and the patient had 9.0 mm pupils. This patient did not appreciate a total elimination of NVD until the optical zone of the contact lens exceeded 10.0 mm. So, there you have the combination of low pre-existing myopia, but extremely large pupils. The pupil variable trumped the myopia in this case. Where's the mystery. By-the-way, it's very difficult to be come to any statistically valid objective conclusions from a sample size of one, especially if that sample is yourself. DrG > If you suffered from constant tinnitus, you would probably learn > to tune it out, but you would probably notice if one day you > awakened and it wasn't there. It happens that I have also constant tinnitus (actually, most likely everybody has in dead silence like everybody has constant noise in their vision as well). I have had it in very audible state for about ten years. It's high pitches around 13-14kHz and so on. Never bothered to measure it because it doesn't have any effect on my life or my hearing. It is very, very audible but still not severe at all. In practice, it does not mask any relevant sound information and therefore I can just totally, completely ignore it (not pay any attention to it). However, with my LASIK starburst the case is completely different. Well. Actually not completely. The only real life-affecting situation is reading music scores. I just watched Star Wars 3 in the theater and although I notice blurring and I know the picture could be so much sharper, impressive and stable, it doesn't ruin the movie for me. Having said that, I want to point out that the amount of masking that the starburst/halo problem does for me is on completely different level than the tinnitus I have. (Of course, note that some people do have severe tinnitus that causes extensive hearing loss etc.) The starburst simply masks huge amounts of image information. As an answer to William's questioning whether starburst/halo is only subjective and not measurable objectively. As I've said here before, my opinion is that this is just, completely a question of right methods. I happen to have some experience in video screen comparison and so on, so I'm used to comparing image quality. But I'm sure that image quality can very well be measured quite effectively even if there's a human eye and visual system in question and the patient does not have so much previous experience on analysing deviation in image. There could be all kinds of "manual" tests, but how about the capabilities of today's wavefront. Can the image seen by the patient be simulated (rendered) simply with the information from the wavefront device? With search terms "wavefront, convolution, simulation" something was found but it required purchase of the article, maybe someone can give good links about this? > 1. How long since you had the (first) surgery? 7 years > 2. Do you see distortion of any kind, in daylight or in dark? If you > answer No, you can stop the survey here, but add a comment about your > vision (be critical, show that you do pay attention to visual quality). yes > 3. Do you see disturbing starburst around small/distant lamps at dark? yes > 4. Do you see disturbing halos around bigger/closer lamps at dark? sometimes > 5. Does the starburst/halo size around lamps change when the pupil size > changes? If yes, does the halo reduce to zero or practically almost zero > (you can test this for example by looking out a window at night and then > constricting the pupils by the use light, eg. flash light)? yes > 6. Has your starburst/halo size or brightness changed after surgery? If > yes, please tell how did you measure this (looking at the same lamps month > after month from the same spot can be a good test). no > 7. Do you see a less blurred image if you look through "finger > binoculars"? Roll your index fingers and look through the small holes > formed. Look at something in room illumination with high contrast, for > example a black poster with white text or a white object on black > background. yes > 8. Do you have difficulties recognizing faces if the person is standing in > front of a bright window -- or do you see everything more or less foggy in > room illumination? sometimes > 9. Your happiness about the result (0-100%), where > - 100% = aquity is 20/20 or better, there are no side-effects [quoted text clipped - 3 lines] > - 0% = major difficulties at reading and recognizing faces, > driving a car at dark is hazardous (or other complications). 50% - although I am completely happy with my outcome and have NO regrets > 10. Your pre-operative prescription, dilated pupil size, perfect > correction optical zone size and transition zone size (if you know them). > And your age, if you wish. -14/-18, BCVA 20/40 > X. If you have something else to comment about your vision, please add it > here. > > Thank you very much for your time and effort! > 1. How long since you had the (first) surgery? I had bilateral Zyoptix performed on june 12 2003. > 2. Do you see distortion of any kind, in daylight or in dark? If you > answer No, you can stop the survey here, but add a comment about your > vision (be critical, show that you do pay attention to visual quality). I did see starburst around bright lights decreasingly the first six months after the surgery, but since then I've had no problem with that or anything else regarding my visual acuity or ability to see details in the dark. The only side effect I've noticed is that my eyes tend to get dry a little easier these days, but not to the extent that I need any tear fluid substitutes, I just blink a little more when I feel that they get dry and it helps. > 3. Do you see disturbing starburst around small/distant lamps at dark? Only the first six months after surgery. > 4. Do you see disturbing halos around bigger/closer lamps at dark? Only slightly the first six months after surgery. > 5. Does the starburst/halo size around lamps change when the pupil size > changes? If yes, does the halo reduce to zero or practically almost zero > (you can test this for example by looking out a window at night and then > constricting the pupils by the use light, eg. flash light)? Not that I noticed during the six months I saw starburst. > 6. Has your starburst/halo size or brightness changed after surgery? If > yes, please tell how did you measure this (looking at the same lamps month > after month from the same spot can be a good test). They're gone now. The first six months I noticed it mostly around headlights of opposing cars while driving in darkness. > 7. Do you see a less blurred image if you look through "finger > binoculars"? Roll your index fingers and look through the small holes > formed. Look at something in room illumination with high contrast, for > example a black poster with white text or a white object on black > background. No. > 8. Do you have difficulties recognizing faces if the person is standing in > front of a bright window -- or do you see everything more or less foggy in > room illumination? No. > 9. Your happiness about the result (0-100%), where > - 100% = aquity is 20/20 or better, there are no side-effects [quoted text clipped - 3 lines] > - 0% = major difficulties at reading and recognizing faces, > driving a car at dark is hazardous (or other complications). 100% > 10. Your pre-operative prescription, dilated pupil size, perfect > correction optical zone size and transition zone size (if you know them). > And your age, if you wish. OD: -5.0/-0.75/175°, dilated pupil size 5.5 mm, optical zone 6.0 mm OS: -4.5/-1.5/177°, dilated pupil size 5.5 mm, optical zone 6.0 mm BCVA pre-op (OD & OS): 36/20 (1.8), bilateral 36/20 (1.8) UCVA post-op (OD & OS): 32/20 (1.6), bilateral 40/20 (2.0) Laser system used was Bausch & Lomb Technolas 217z with Chiron Hansatome 160 ?m (for both eyes). My age at the time of surgery was 35, I'm 37 today. > X. If you have something else to comment about your vision, please add it > here. > > Thank you very much for your time and effort! Here we have a patient whose optical ablation zone was 0.5mm larger than pupil size, and yet he experienced temporary night vision problems. This is consistent with the studies that pupil size alone is a poor predictor, albeit in this case the existence of night vision problems resolved during the normal six month healing period. Also note that the Zyoptix wavefront-guided ablation was not generally available in the US at the time of the patient's surgery. 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. I'm not sure that proves what you think it proves. It merely proves that LASIK can induce NVD's even if the programmed ablation zone is larger than the ostensible pupil size. Only topography would show whether the actual ablation was as large as planned, and only very careful measurement will reveal the actual size of the pupil under scotopic conditions. What is doesn't prove is that a patient with an ablation zone smaller than their scotopic pupil size will not have NVD's. DrG Of course, this one case isn't adequate to make conclusions, but to me it seems like it's perfectly consistent with my "theory". Larger pupil than perfect ablation zone causes severe, possibly non-healing distortion and the other type of distortion (which doesn't change radius with pupil size) heals more easily and that healing is much easier to explain than the healing of the transition zone. > Only topography would show whether the actual ablation > was as large as planned I would guess that at least with equipment of today's generation the lasering part is close to fool-proof itself, what changes the mathematically predicted result is what happens with the flap, alignment and growth of cells, hydration etc. (And what is the mathematically predicted result is not the ideal result if/because there isn't enough of stroma to ablate.) > only very careful measurement will reveal the actual size of > the pupil under scotopic conditions. I really don't know how it's with others, but my pupils seem to behave quite consistently - I think they're quite reliably close to the maximum always when it's dark. The reaction time of pupil is also very minimal (about 200ms or so). Therefore I would imagine it should be easy to make quite reliable measurements. Of course, only one small but bright light source can change the result greatly. I don't think it has to be absolutely pitch black to make a decent measurement. I'm sure I would find out problems with measurement reliability though if started doing it for my living. > Of course, this one case isn't adequate to make conclusions, but to me it > seems like it's perfectly consistent with my "theory". Larger pupil than > perfect ablation zone causes severe, possibly non-healing distortion and the > other type of distortion (which doesn't change radius with pupil size) heals > more easily and that healing is much easier to explain than the healing of > the transition zone. I admit to have trouble following your "other type of distortion." Do you mean a non-homogeneous area of ablation, edema, or something else? > > Only topography would show whether the actual ablation > > was as large as planned [quoted text clipped - 4 lines] > cells, hydration etc. (And what is the mathematically predicted result is > not the ideal result if/because there isn't enough of stroma to ablate.) Foolproof, you say? Why do calibrations, then? I think you need to take a look at what happened as opposed to what was supposed to happen. If it happened the way it was supposed to happen, then you can make a case for a design flaw. > > only very careful measurement will reveal the actual size of > > the pupil under scotopic conditions. [quoted text clipped - 8 lines] > find out problems with measurement reliability though if started doing it > for my living. I think you might have missed my point, which is that there is lack of consistency not only in the devices used to measure pupil size, but also in the conditions used to measure pupil size. If one states the pupil size, then one needs to qualify how it was measured. DrG > I admit to have trouble following your "other type of distortion." Do > you mean a non-homogeneous area of ablation, edema, or > something else? I mean to continue saying what I said on that message from yesterday which begins "Ok.". There I put my speculation about the causes. If I wasn't clear, there were mistakes or it is difficult to understand what I wrote, I'll be glad to discuss about it. Basically what I called "second type of distortion" is caused by light being scattered because of the changes between the surface of the stroma and the epithelium, where cellular structure is violated (and cracks etc. easily visible to the ultrasound are present as well). > Foolproof, you say? Why do calibrations, then? I don't know at all how they calibrate it. If it's human calibrated at micron level (as opposed to rough positioning), I'm surprised. At least I suppose the real-time eye tracking has to be very highly effective and accurate. I accidentally turned my eye completely at the wrong direction in the middle of lasering, but that eye is actually the better one now. > If it happened the way it was supposed to happen, then you > can make a case for a design flaw. I would imagine that with today's generation equipment it is not a problem to make very accurate lasering. And that when unpredicted result occurs, it's rarely because of inaccurate lasering but because of the unpredictable nature of the stuff piled back on the stroma (and the space between the stuff and the ablated stroma). > I think you might have missed my point, which is that there is lack of > consistency not only in the devices used to measure pupil size, but > also in the conditions used to measure pupil size. Yes, it is possible. But I find the task quite simple compared to many other things humans are capable of (the required accuracy is just 0.01mm level which shouldn't be that difficult). Let's analyse it at practical level: if the measurement is made always horizontally and the equipment has 0.1mm accuracy (including the deviation caused by different interpretation) and the sealed room is very dark, is there much that can go wrong? If the situation is something like so that the devices have 0.5mm accuracy (or huge differencies among different models) and the room illumination is sometimes dark and sometimes lots of light is coming in through the windows - well, then something is horribly wrong. What is the purpose of measuring pupil size if it's not confirmed that the method and conditions are accurate? > This is consistent with the studies that pupil size alone > is a poor predictor But this doesn't mean that the whole business is a total and unsolvable mystery (I know you don't think so either). There are simply simultaneously different causes for NVC. In my speculation, pupil size is a very good predictor for the transition zone induced problem. And, simply, there is also other kind of disturbance which can be similar to the transition zone induced disturbance, but they are still (easily) separable. Pupil size indeed doesn't have very much to do with this "second type" disturbance. > Also note that the Zyoptix wavefront-guided ablation was not generally > available in the US at the time of the patient's surgery. To me it seems that wavefront does not offer a solution to the biggest problem, which is the transition zone problem. The wavefront doesn't grow more thickness to the stroma which is what would really help. >To me it seems that wavefront does not offer a solution to the biggest >problem, which is the transition zone problem. The wavefront doesn't grow >more thickness to the stroma which is what would really help. It is my understanding that the transition zone does not benefit from wavefront analysis. The transition is essentially a conventional ablation. 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. >1. How long since you had the (first) surgery? 3 years >2. Do you see distortion of any kind, in daylight or in dark? If you answer >No, you can stop the survey here, but add a comment about your vision (be >critical, show that you do pay attention to visual quality). Yes. >3. Do you see disturbing starburst around small/distant lamps at dark? At night, I see "slight" starbursts around small/distant lamps. It is almost unnoticeable, but I am very "picky" about my vision. >4. Do you see disturbing halos around bigger/closer lamps at dark? Not any more, although I did for the first 18-24 months after surgery. >5. Does the starburst/halo size around lamps change when the pupil size >changes? If yes, does the halo reduce to zero or practically almost zero >(you can test this for example by looking out a window at night and then >constricting the pupils by the use light, eg. flash light)? Yes and yes. >6. Has your starburst/halo size or brightness changed after surgery? If yes, >please tell how did you measure this (looking at the same lamps month after >month from the same spot can be a good test). I had changes all along, but the most dramatic changes were during the 18-24 month period after surgery. I "measured" this by looking at the same street lights in my neighborhood from month to month. >7. Do you see a less blurred image if you look through "finger binoculars"? >Roll your index fingers and look through the small holes formed. Look at >something in room illumination with high contrast, for example a black >poster with white text or a white object on black background. Yes, no distortion at all. >8. Do you have difficulties recognizing faces if the person is standing in >front of a bright window -- or do you see everything more or less foggy in >room illumination? No, although these were issue during the first 6 months or so after surgery. >9. Your happiness about the result (0-100%), where > - 100% = aquity is 20/20 or better, there are no side-effects [quoted text clipped - 3 lines] > - 0% = major difficulties at reading and recognizing faces, > driving a car at dark is hazardous (or other complications). 100%, now that my eyes have "healed." I would say 75% for the first 3 months after surgery, gradually rising during the 3-month to 24 month period to 100% now. >10. Your pre-operative prescription, dilated pupil size, perfect correction >optical zone size and transition zone size (if you know them). And your age, >if you wish. -6.5 left, -6.0 right, 6.5 mm, but I don't know optical and transition zone sizes. Age is 43. >X. If you have something else to comment about your vision, please add it >here. I would just say that patience pays off. I was a little upset and the starbursts/halos, and I certainly thought they would have "gone away" quicker than they did. Now that they're practically unnoticeable, I am a happy camper. >Thank you very much for your time and effort! No problem. Great idea! |
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