A Comparative Study on Accuracy of SRK-T And Haigis Formulas in IOL Power Calculation in Axial Myopes Undergoing Cataract Surgery.

Abstract

Background and Objective:It has been a significant challenge since the advent of intraocular lens to give the best postoperative visual acuity and prevent refractive surprises due to biometry error. Among myopic eyes, it has been a debate among the various formulas introduced and their efficacy to prevent postoperative refractive surprises. Hence, the need for an accurate formula in high myopic eyes is obligatory.Objectives of the Study:To compare the accuracy of SRK-T and Haigis formulas in IOL power calculation in axial myopic eyes undergoing cataract surgery.Methods:A total of 50 cases with axial length >24 mm were taken up for the study and were examined in detail and error between both formulas were assessed.Results:The mean age of the subjects in the study was 53.50 ± 16.12 years; 27 were males, and 23 were females. The majority of patients had PSC + NS II. Seven out of 50 cases had posterior staphyloma. Most of the patients had average K value in the 44–46-D range. AL of most of the patients (66%) was between 24 and 26 mm. The majority of patients had IOL power >15 D, and 82% (41 eyes) were found to have no post-op complications. Four eyes had severe iritis, and five eyes had striate keratopathy. At the follow-up at 6th week postoperatively, 82% were found to have 6/6–6/9 vision on Snellen's chart. Four eyes had 6/12–6/24 post-op vision, mainly attributed to primary PCO. Five eyes (10%) had <6/24 post op vision at the end of 1 week due to the presence of posterior staphyloma. A higher percentage of eyes in the SRK/T group had a mean error >0.5 D. Upon comparing the mean error between the two groups, P was 0.005; hence, the results are statistically very significant, showing that Haigis formula is better than SRK/T formula in achieving target refraction (−1) in myopic eyes undergoing phacoemulsification.Interpretation and Conclusion:Our study shows that Haigis formula was better than SRK/T formula for achieving the target postoperative refraction in high axial myopes.