Sir,

With great interest I read the paper on IOLMaster vs theoretical calculations in Eye (2006) 20: 90–97.

My experience, however, with the HofferQ implementation and the IOLMaster is different and I wonder what the reasons might be.

Looking at the code at the bottom of page 95, in the Function HofferQ, there is the statement ACD=AtoACD(ELPtoA(ELPconst)). The variable ACD is later used to calculate the predicted ACD in ACD=ACD+0.3* …

The ‘ACD’ on the right side of this equation/definition actually should be the HofferQ IOL constant ‘pACD’, that is, in the expression ACD=AtoACD(ELPtoA(ELPconst)) ‘ACD’ should play the role of ‘pACD’ in the original HofferQ publication. Why convert ELPconst → A → ACD?

Trying to reproduce the example 1 (emmetropic eye A=23.5, K=43.5)) in Hoffer's original paper of 1993, the predicted ACD for an IOL constant pACD=4.50 should be 4.40887.

Assuming that the variable ELPconst stands for pACD then I have a problem understanding the conversion ELPconst → A → ACD. ACD=AtoACD(ELPtoA(ELPconst)) would turn out to be 4.46591 instead of 4.50 and the predicted Hoffer ACD would be 4.37479 instead of 4.40887. Could this explain the problems that were observed? The function HofferQ needs the entry of whatever stands for the paper's ‘pACD’ in the nomenclature. Which variable in the code plays this role?