Study of accuracy of biometric measurements in relation to intra ocular lens power calculation

Abstract

Preoperative eye biometric measurements are critical for calculating IOL power, so it is essential to grasp how the various biometric parameters interact. The aim of this study is to determine the predictability and influence of biometric values on power calculation.To determine the relationship between IOL power and biometric values.It is an observational cross-sectional study done at a tertiary care center in Mysore, Karnataka. 110 eyes undergoing cataract surgeries were evaluated in the study over a period of four months. Preoperative biometry was performed and IOL power was calculated by SRK–II and A-scan. Pearson correlation coefficient matrix was tabulated. Model was obtained using multiple linear regression analysis. The comparison was made among all 6 models using the R square value and the standard error of the estimate.Ka had a positive correlation with the Kh (r=0.955) and Kv(r=0.963), which had a weak negative correlation with AL (r =-0.358). Model 2 (SRK II-IOLP= (-0.900)*Ka + (-2.500)*AL+118.200) had the highest R square with no error, indicating the highest predictability in estimating IOLP. Estimating IOLP using an A-scan was a significant predictor but had the highest error with an R Square value of 0.206.Model 1 (A-scan- IOLP=(-0.191) *Ka +(-1.002)*AL+52.445) was the second most successful model. Ka can provide better predictability with both the methods to calculate the IOLP and AL.There is a limited evidence in comparing both the formulas. The SRK-II IOLP measurement showed higher accuracy using Ka and AL with no error in refractive error. A scan provided precise biometry data and IOL power calculation within an average range of ALs. The SRK- II formula's predictability is higher than the A-scan formula.