Interpreting IOL card

[pinhole]

My husband had his second cataract surgery today a month after the other eye. The agreed-upon goal was to have one eye for reading and the other eye for distance, as he has always used his eyes that way lifelong. His IOL cards for the ZCB00 lens show the same diopter (+19.5D) and both show 13mm and 6 mm for the other readings. I somehow thought the card info would differ between the eyes. Thank you for any explanation.

[John C Hagan III, MD, FACS, FAAO]

You can't get much information from just looking at the IOL power.  There are various IOL formulas for predicting the post operative desired residual refractive error.  Varibles includ the shap of the cornea, the depth of the anterior chamber, very very important the axial length of the eye,  the type of IOL being used and a factor based on the surgeon's experience using that formula for theorectial desired refractive error and actual.  If you are interested you might ask your surgeon to show you or print you up a copy of the results of each eye.

[pinhole]

Thank you, Dr. Hagan. In all this I am confident my husband's final result will be great. It already is. Your emphasis on the importance of axial length may shed light on why my own IOLs are two (2) diopters apart. (I think an encircling scleral buckle affects axial length.) Anyway, thank you again for pointing out the limits of the IOL power and for the suggestion to ask my husband's surgeon about the desired vs. actual refractive error. By the way, as someone who's had retinal detachments in both eyes, I'm always happy to see your oft-repeated advice to readers who've had one retinal detachment to take care of their second eye. Many thanks again.

[John C Hagan III, MD, FACS, FAAO]

Happy to help pinhole.  The longer the eye, the less power is needed. So since scleral buckle increased axial length your IOL powers should be lower than normal.  If you have children be sure they are aware of your RDs and the symptoms of same. The risk to them is higher than normal especially if highly myopic

[Ron_AKA]

In rough terms when a person that has near perfect eyes (prior to cataracts) gets an IOL for distance vision the power used is right around +19.5 D mark. That power does not correct for myopia or hyperopia. It just replaces the power of the natural lens removed. So from that I am assuming the eye that is intended for distance had very good uncorrected distance vision before cataracts and it needed no significant correction.

I am also guessing that the other eye had some modest myopia perhaps in the range of -1.50 D. The "neutral" +19.5 D lens is not going to significantly correct that eye, and leave the myopia pretty much where it was already. If that eye was going to be corrected for full distance then a lower power lens would be used like a +17.5 D or so. But, that is not the intent in this case.

Keep in mind that these are just rough assumptions. In actual practice the eye is precisely measured and the target for outcome is input into a computer program and the computer selects the correct power (hopefully) to get the desired outcome. The bottom line is that because the same power lens was used in each eye, that does not mean the outcome will be the same.

And, the real test of success is getting a refraction done at 5-6 weeks after surgery to see where the eye really lands. The normal target for the monovision you describe is -0.25 D in the distance eye, and -1.50 D in the near eye, if it is mini-monovision.

Hope that helps some

[pinhole]

Thank you very much for taking the time to explain so thoroughly! Yes, that clarifies things and prepares me better for the one-day post-op visit tomorrow. Sounds as if everything is as it should be. Again, thank you.

[Ron_AKA]

It would be a good idea at your visit to ask for a copy of the IOL Power Calculation sheet. It will show what the target was for each eye, and the power of lens needed.

[John C Hagan III, MD, FACS, FAAO]

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