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Comparison of spherical equivalent determined by Sanders-Retzlaff-Kraff-II (SRK-II) formula with target post-operative final refraction in patients undergoing cataract surgery

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Original Article

Author Details : Ruchi Kabra*, Krupali Raol, Hemaxi Desai, Riddhi Gajjar, Deep Panchal, Rajendra P Maurya

Volume : 9, Issue : 4, Year : 2023

Article Page : 511-515

https://doi.org/10.18231/j.ijceo.2023.097

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Abstract

Background: The most challenging subject in patient satisfaction after cataract surgery depends upon post-operative refractive outcomes. Accurately predicting post-operative refraction is necessary during the calculation of Intraocular lens (IOL) power. The Sanders-Retzlaff-Kraff (SRK) II formula is one of the few formulae being used for the calculation of IOL power. Our study is to compare the accuracy of the SRK-II formula with targeted final refraction of patients undergoing phacoemulsification.
Materials and Methods: This study was performed on 102 eyes that underwent phacoemulsification. IOL power was calculated using the SRK-II formula. One and a half months after surgery, refraction was performed. Differences between actual post-operative refraction and predicted spherical equivalent was calculated and termed absolute refractive error. Paired t-test was used for comparing actual post-operative refraction and predicted spherical equivalent.
Results: The mean absolute error (MAE) of the SRK-II formula was 0.44 D (diopters) overall. The percentage of eyes within ±0.5 D of the predicted spherical equivalent was 81%. Patients having post-operative refractive error within ±1.0 D for short, average, and long axial length were 88% (P value 0.21), 92% (P value 0.0009), and 91% (P value 0.18) respectively.
Conclusion: We found that the SRK-II formula was accurate and reliable for predicting the post-operative refractive error in eyes with normal axial lengths as the post-operative refraction is near emmetropia and is a good method for IOL power calculation with normal axial lengths.
 

Keywords: Phacoemulsification, Post- operative refractive error, IOL power calculation, SRK-II formula, Axial lengths, Spherical equivalent, Post-operative target refraction.

How to cite : Kabra R, Raol K, Desai H, Gajjar R, Panchal D, Maurya R P, Comparison of spherical equivalent determined by Sanders-Retzlaff-Kraff-II (SRK-II) formula with target post-operative final refraction in patients undergoing cataract surgery. Indian J Clin Exp Ophthalmol 2023;9(4):511-515

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