correct astigmatism or spherical aberration?

[Chuckles960]

I have a small cylindrical correction of -0.5 (90o) in the eye that now needs surgery for cataracts, and a much larger correction of  -1.75 (80o) in the other one, which will need surgery in a few years.

From my limited googling, it seems there are aspheric IOLs and toric IOLs but no aspheric toric IOLs. Is this correct?

If so, for the -0.5 cylindrical correction, would I benefit more from correcting the astigmatism with the IOL, or from correcting any spherical aberration?

What if my eyes don't have enough spherical aberration to be worth correcting? An ideal spherical-surface lens has spherical aberration, but my eye isn't perfectly spherical (if only because it is partly cylindrical), so either it has more spherical aberration than normal, or possibly it has less; I don't have a clue. How is it decided that an eye has spherical aberration, and are there different grades of asphericity available in IOLs?

For the other eye (cyl -1.75/80o), when the operation is ultimately done, I assume that a toric IOL would definitely be more important than an aspheric IOL? Or, given that there's a good chance I'd be using glasses anyway, would one opt to leave the cylindrical correction to the glasses?

I hope these are not overly esoteric questions. I want to be prepared for my next visit...

[Michael J Kutryb, MD]

SUggest a second opinion before any transplant procedure - perhaps you have keratoconus?

MJK MD

[sue845]

My doctor says I need a cornea transplant due to a corneal abboration.  I'm confused.  I went in for reading glasses, he said I had a astigmatism
and now a cornea transplant.  He says it's very easy and low risk in the hands of a qualified physician.

My vision in one eye has a slight downward curve and in the other eye an upward curve.  Together they compensate, but at times things are really out of focus.  

Thoughts?

[Chuckles960]

OK, thanks! I have googled LRI and your advice makes complete sense.

[Michael J Kutryb, MD]

There is no toric/aspheric lens, at present.  Most doctors are not able to measure true spherical abberation - but if you had abberometer or topographer with software to calculate true spherical abberation you could actually match as closely as possible the aspheric IOL to the patient because the tecnis, acrysof IQ and sofport AO all have slightly different levels of spherical abberation.  That's getting really, really technical.  Most patients will do great with any of the three and any slight edge one might possible get by IOL matching would likely never be noticed by patient.  Now for your case - I suggest an aspheric monofocal IOL for right and same for the left with Limbal relaxing incisions to correct the amount of corneal astigmatism as measured by corneal topography or IOL MASTER if necessary.  You have to make sure of the amount of corneal astimatism not just the  amount of astigmatism in your glasses because it is usually different.  Your second option in astigmatic eye is to have an acrysof toric IOL.  It all depends or what your surgeon is comfortable with.  It depends or several factors - talk it over with surgeon.  Right now I personally use aspheric and Limbal relaxing incisions BUT am looking to start with toric IOLs for select patients in the very near future.  They have their own little quirks and are not foolproof by any  means.

MJK MD