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Comparison of the accuracy of intraocular lens (IOL) formulas regarding refractive errors in patient candidates for cataract surgery

Poster Details

First Author: A.Ayati IRAN

Co Author(s):    A. Pakmehr   S. Mirshahvalad   A. Moradi   F. Noorizadeh   A. Shojaee Baghini        

Abstract Details


To evaluate and compare predictability and accuracy of different formulas for Intraocular lens (IOL) power calculation in patients candidate for Cataract surgery.


Basir eye clinic, Tehran, Iran


This retrospective cross-sectional study included 196 eyes from 98 patients who were candidates for Cataract surgery in Basir eye clinic. 3 IOL power formula predictions with observed refraction after cataract surgery were compared. Preoperative IOL power calculations were performed using SRK/T. Actual lens power was calculated by summing Postoperative refractive error with used IOL power. The mean estimation error (MEE) ,R square, Akaike's information criterion (AIC) and Bayesian information criterion (BIC) were calculated and compared for all three formulas.


Results of paired sample T test revealed correlations of 0.88, 0.92 and 0.98 between actual refraction and estimations of Barrett Universal II, Hill RBF and SRL/T, respectively (P<0.001). In calculated linear regression model, chi- square's value was reported as 188.47, 274.39 and 55.11, AIC was reported as 554.54, 628.17 and 313.55, BIC was reported as 564.37, 638 and 323.38 for Hill RBF, Barrett Universal II and SRK/T, respectively. MEE was calculated 0.85, 0.97 and 0.20 for Hill RBF, Barrett Universal II and SRK/T, respectively. The SRK/T formula showed the least mean estimation error among used formulas (p< 0.001).


In this study we reviewed three IOL power calculation formulas. As mentioned in results the SRK/T formula had the least mean estimation error among used formulas. We advise SRK/T formula for power calculation in similar epidemiological areas.

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