Abstract
Purpose: :
To compare the accuracy of the predictions of SRK–T and Haigis Formulae, incorporating all the parameters calculated using Zeiss IOL Master Scan, based on Partial Coherence Interferometry.
Methods: :
A retrospective study was done on 50 patients, who underwent phacoemulsification by a single surgeon with a temporal corneal incision and a standard Alcon Acrysof MA30 implant in the bag. The pre–operative data were measured using Zeiss IOL master scan and the IOL power calculations were done using both SRK–T and Haigis formulae. The final implant power selection was based on SRK–T predictions. The patients were divided into 3 groups depending on the axial length (<22mm, 22–24mm, >24mm) . The post–operative results were analysed at 4 weeks.
Results: :
The difference between the predicted value and the post–operative spherical equivalent was calculated for both the formulae for the different axial length subgroups .This difference was found to be less with Haigis formula than SRK–T in all axial length subgroups.
Conclusions: :
Achieving the predicted post operative refraction is a challenge for every cataract surgeon and the issue of choice of IOL formula to be used for calculation is important. Haigis formula was found to be more accurate than SRK–T formula in predicting post operative refraction results.
Keywords: intraocular lens • crystalline lens • clinical research methodology