Comparison Of The Accuracy Of Five Intraocular Lens Power Calculation Formulas For Eyes After Myopic Lasik

To assess the accuracy of five IOL power calculation formulas for eyes with cataract with history of prior myopic LASIK.

Nethradhama Superspeciality Eye Hospital, Bangalore, Karnataka, India

This retrospective case series included patients with history of prior myopic LASIK undergoing cataract extraction. IOL power was calculated using Barrett True-K ,Barrett True-K TK, Holladay EKR, Haigis-L  and Ray tracing formula. Prediction error, Mean absolute error (MAE) and median absolute error (MedAE) of predicted refraction were com­pared for each formula.

40 eyes of 24 patients were analysed.Mean prediction error(PE) for all the five formulas was significantly different from zero(p<0.001).However, there was no significant difference observed between MAE of all the formulas(0.42±0.40D for the Barrett True-K,0.43±0.46 D for the Barrett True-K TK,0.39±0.43D for Holladay EKR,0.45±0.43D for the Haigis-L and 0.43±0.54D for Ray tracing),p>0.05.Similarly,the MedAE of all the formulas was also not found to be statistically significant,p>0.05.Percentage of eyes within ±0.50D was 59.4%,58.9%,56.3%,57.7% and 56.3% for Barrett True-K TK, Barrett True-K,Haigis L,Holladay EKR and Ray tracing formula respectively.

All the five modern post refractive surgery IOL calculation formulas were effective and resulted in comparable accuracy.

Financial Disclosure: Dr. Sri Ganesh and Dr. Sheetal Brar are consultants to Carl Zeiss Meditec.