Is the Frequency distribution of eyes graph comparing the postop refraction to target that is entered on the preop screen or is it comparing the postop refraction to the actual spherical equivalent of the power/model lens that was placed in the eye?

On the IOL CALC SCREEN and PRINTOUT there is a PREDICTED SEQ REFRACTION for several IOL Powers. The Prediction Error is the difference in the ACTUAL POST OP REFRACTION subtracted from the PREDICTED REFRACTION for the IOL POWER & MODEL that was implanted and entered on the SURGICAL DATA SCREEN.

Secondly, under selection criteria, pred error…say we enter -.50 to .50, is that graph showing us how may patients final postop refraction (spherical equivalent) fell within a half diopter of projected target?


We have the Holladay 2 program and I haven't taken advantage of the back calculation feature until now. I've printed out results for a patient with a post -op myopic surprise and am trying to understand all the numbers. How is this printout helpful in knowing what "went wrong" with our calculations?

The BACKCALC determines what value for each of the five variable that would have given the desired result using the ACTUAL VALUE for the other 4. So, if the axial length were 22.187 mm instead of 21.79, the result would have been perfect. So you go back and check the REFRACTION, AXIAL LENGTH and KERATOMETRY and see if any are wrong. This way you can find the error.

After entering enough data for statistical significance, do the graphs in the program autopopulate or is this info that I must enter and where do

They auto-populate … you do not need to re-enter anything.