A Simple Method Using Excel For Triple Optimization Of The Haigis Formula
Published 2024 - 42nd Congress of the ESCRS
Reference: PP05.08 | Type: Poster | DOI: 10.82333/crpw-s198
Authors: Umberto Camellin* 1 , Massimo Camellin 2 , Gianluigi Latino 1 , Federico Merlin 3 , Gabriele Vizzari 3 , Piero Ceruti 3 , Pasquale Aragona 1
1Ophthalmology,University of Messina,Messina,Italy, 2Sekal Microchirurgia,Rovigo,Italy, 3Ophthalmology,Hospital of Legnago,Legnago,Italy
Purpose
The Haigis formula predicts the effective lens position (ELP) based on a0 (intercept constant), a1 (dependent on the depth of the anterior chamber depth [ACD]), and a2 (dependent on the axial length [AL]). The purpose is to develop a easy method using only the.xlsm file for the constants (a0,a1,a2) optimization of the Haigis formula. Unfortunately, The "Goal SeeK" tool inside "Excel" program is a function that cannot be automatically repeated for the entire sample but must be performed manually. To automate this process, we developed a modified "function macro" (.xlsm) with Microsoft Visual Basic. Thanks to this, this step is performed automatically in the constant column.
Setting
Sekal Microchirurgia Rovigo, Italy
Methods
Biometric and postoperative refraction data were collected from 185 virgin eyes who underwent phacoemulsification and IOL implantation (FIL-622-1,Soleko,Italy).The Haigis formula was added to the "xlsm file” with random constants and the postoperative SpheroEquivalent(SE) was set as the refractive target.The calculated IOL power was compared with the implanted one (Delta, D).To optimize the constants, it was find the value of ELP for each patient who gave a Delta of 0.00 D.Instead of inverting the formulas, we used the "Goal Seek" tool in Excel.Objective:“Delta=0.00” by modifying the 'ELP'cell.Thus,we obtain the ideal constant for each patient.To automate this process,we developed a modified "function macro" with Microsoft Visual Basic.
Results
The mean and standard deviation of data were: 3.26 ± 0.40 mm for ACD, 4.58 ± 0.46 mm for LT, 43.96 ± 1.47 D, for AL 24.04 ± 1.60 mm, 20.15 ± 4.06 D for IOL Power and -0.38 ± 1 D for Postoperative Spheroequivalent Refraction (SE). The ELP was given by formula = -1.808 (intercept =a0) -0.061(=a1)*ACD+0.307(=a2)*AL.
Conclusions
Since in the Haigis formula, ELP depends on a0, coefficient of preoperative ACD (a1) and coefficient of AL (a2); it was sufficient to calculate a multivariate linear regression formula using the Excel data analysis tool: which has preoperative ACD and AL as independent variables and ELP as a dependent variable. In conclusion, it was possible to perform the triple optimization of the Haigis formula using Excel alone for the IOL FIL-622-1.