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General Information on Intraocular Lens Power Determination

Aug 27, 2015 - 0 comments

Hello Garrett,    Your mother's optical situation is not uncommon. Choosing an intraocular implant (IOL) power to give the best vision unaided by glasses is as JodieJ says not an exact science. It is much, much better than 5-10 years ago and it will be better 5-10 years from now. It will never be 100%. Like much of medicine we are sometimes a victim of our own success. There was a time in which patients were happy to go through a cataract operation without a major complications and wore regular glasses happily after surgery.

As we have been able to improve the vision without glasses some people expect to see perfect without glasses even though this is not possible for many people and something an ethical surgeon never promises or guarentees.  There are many variables (radius of curvature of the cornea, axial length of the eye, position of the IOL in the eye, etc) that can cause the actual result of surgery to differ from the "theoretical" values used in the pre-operative calculations. There is not even one forumula that surgeons agree is "best" to use for the calculations. As eyes become longer than normal or shorter than normal the possibility of under/over correction increases significantly.

Some eyes, because of astigmatism, are not correctable with the standard monofocal implants used in most surgeries. Even with the new multifocal "premium" IOLs that are used to try and get away from glasses completely for all distances often require glasses for certain tasks and certain distances (use the search feature and look at all the complaints).

Of course it is possible to have  gross miscalcuations due to error in data acquisition or data entry. These are rare compared to the normal "scatter".

Wearing progressive bifocal lens to achieve good vision is the expected and hoped for result of standard monofocal IOL surgery. Some people will see satisfactory at distance without glasses, others will see okay at near or mid range without glasses but this is a bonus not the expected result. We never tell our patients that they will be able to go without glasses. We tell them it often happens but we expect they will need glasses. Period.

There are certain circumstances in which if the difference is way to much to wear glasses (say a 4-5 diopter difference) that the information can be sent to a Medicare review or insurance review committee to authorize a LASIK procedure and have it paid for by insurance/Medicare (of course deductibles or co-payments would legally have to be collected). If glasses are feasible and wearable do not expect them to authorize the LASIK.

As to your physician's behavior, again Jodie J may be right. If you've gone to this ophthalmologist (Eye MD) for quite some time and he/she is generally even tempered and patient, I would cut them some slack. On the other hand if the physician is usually this way then I would seek not only a second opinion but a new ophthalmologist. I am a very patient physician and very even dispositioned but I have "lost it" on a few occassions with my patients. I always felt terrible afterwards and in most cases have called back to apologize the next day. More than one of these occured during a stretch where in addition to my professional responsibilities I was taking care of a sick parent and another member of my family was seriously ill.

Compared to some of the really serious sight threatening complications that are often posted here I think your mother has some really excellent options.


Original MedHelp Blog - Dec 11, 2009

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