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Medical Forum / General / Vision / November 2006Cataract lens replacements
Is there some source or sources that is essentially a "Consumer' Report" on the various lens replacements. How well they are working out. Don W. > Is there some source or sources that is essentially a "Consumer' > Report" on the various lens replacements. How well they are working > out. > > Don W. The answer to that is no. DrG > > Is there some source or sources that is essentially a "Consumer' > > Report" on the various lens replacements. How well they are working [quoted text clipped - 5 lines] > > DrG Well, the first question to that is, why not? They are mechanical devices and just like anything else, prone to failure, adaptability, etc. I had read a report once where yellow implants (the transparent ones of course?) were substituted for clear ones. And that they had offered to exchange them for the error. No takers. The field must be replete with stuff like that. Don W. The problem is that there are no seriously objective methods for comparing the various iols in common usage. On top of that, the surgeons mostly determine the outcomes on very subjective reports by the patients, and even lifestyle evaluations. If the patient is 20/happy, then it was a success, even if they are only 20/30 in dim light and their contrast sensitivity sucks (as it does with the "complex" lens designs, which is why I always recommend single vision prolate optics for iols) wstacy, o.d. > > [quoted text clipped - 22 lines] > > > The problem is that there are no seriously objective methods for > comparing the various iols in common usage. On top of that, the [quoted text clipped - 6 lines] > > wstacy, o.d. Well, are there not multifocal point designs where the patient has to relearn on how to focus his eye (in some not quite natural way). This may be what you are talking about, so please excuse. I understand that some of the multifocal lenses do not continously focus over the entire range. That there is a null spot in the range where it does not focus. I would wonder how this can be (if I am understanding that correctly). But all in all, would there not have to be some kind of clinical trial on these devices? Don W. > Well, are there not multifocal point designs where the patient has to >relearn on how to focus his eye (in some not quite natural way). Mostly the patient hast to learn how to accept poor vision in low light and low contrast situations. You can't re-learn through permanently blurred vision. If you are talking about the focussing iols (moving ones), they don't move nearly enough to work well, and in most cases I think they don't move at all. > This >may be what you are talking about, so please excuse. I understand that [quoted text clipped - 3 lines] > > That is true, they have two focus distances, and the distance between those two is going to be out of focus. But worse than that, even at the distances they are set up for, the other distance focal part of the lenses transmit out of focus light to the retina. You can't relearn around the fact that at least 50% of the light coming to the retina is out of focus at all times and all distances. > But all in all, would there not have to be some kind of clinical >trial on these devices? > > Of course. But the criterion for success was "is the patient happy and can they get along without glasses?" So they were approved. Even a slug can get along without glasses and is probably happy. w.stacy, o.d. > Well, the first question to that is, why not? They are mechanical > devices and just like anything else, prone to failure, adaptability, Well, I don't know "why not." Perhaps you are coming from a reliability/quality assurance background. In that case, why not take it upon yourself to begin such an endeavor on the behalf of future patients.? DrG |
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