ASCRS 2024: Comparing keratometry and total keratometry values in a large dataset

At this year's ASCRS 2024 meeting, Jascha Wendelstein, MD, spoke with Ophthalmology Times Europe about the outcomes of using keratometry versus total keratometry values, in both special and normal eyes.

Editor's note: The below transcript has been lightly edited for clarity.

Hello there, my name is Jascha Wendelstein. I'm currently practicing in Switzerland and Austria: university clinic in Austria, private practice in Switzerland. My main base, or my main interest, is cataract surgery, IOL calculation and refractive surgery, with a bit of corneal surgery and keratoconus too. A very big study, which was published and also presented here [at ASCRS] was a study that compared K [keratometry] and TK [total keratometry] values.

Now, why did we compare them? Previous studies of our group, which was basically Oklahoma City University, David Cooke [Great Lakes Eye Care, St. Joseph, Michigan], and myself, we looked at K and TK values, in special eyes. Basically eyes after laser vision correction, eyes after DMEK surgery, and also with keratoconus, so to say. And we saw that TK values work in all those eyes. They were better than the K values. But the next question is, are the TK values overfitted? Do they still work in normal eyes to change something? And we were able to acquire quite a large data set for it 117,000 eyes, which we assembled in that, and we looked at the differences between K values and TK values.

We found that 94% of those eyes were within a quarter diopter, 99% of the eyes were within half a diopter. So no big differences. The 1% was explained by very few eyes that were suspicious for previous laser vision correction, but with a retrospective study, of course you'll get those eye. The rest of the eyes, obviously, no big differences. So K values seem to be fine, TK values seem to be better, not only in special eyes, also in normal eyes. So, greenlight for the use of TK values as the as the default value in your IOLMaster 700 [ZEISS]. Make use of it. You can do it. Have good success using them!