Study of accuracy of axial length measurements by two biometric methods with reference to post operative spherical equivalents in patients undergoing phacoemulsification

Abstract

Cataract surgery demands refractive accuracy. To achieve this, accurate biometry is required. So two biometry methods should be compared for accuracy. To compare accuracy of immersion USG and optical biometry with reference to AXL measurement and postphaco refraction. Prospective study was done involving 60 eyes of 60 patients undergoing phaco with foldable IOL implantation under LA. Biometry of Group A was done by immersion USG and that of group B was done by optical biometry (30 patients in each group). Detailed preop examination was done. Calculations of IOL power in all patients were done by using SRK/T formula. At 1 month f/up, spherical equivalent was noted. Using regression formula, emmetropic IOL powers and their differences with implanted IOL powers were calculated. Statistical analysis was done using unpaired t test. : Mean AXL in group B (23.2157 mm) was slightly longer than that in group A (23.2093 mm), {P=0.9754}. Mean spherical equivalent at 1 month f/up in group B (0.4583) was slightly lesser than that in group A (0.4625),{P=0.973}. Mean of differences between emmetropic IOL and actual IOL implanted was lesser in group B(0.6877), than that in group A(0.6932), {P=0.9762}.Difference in mean AXL and mean postop spherical equivalent between two methods of biometry were not statistically significant. Immersion USG biometry has accuracy comparable to optical biometry.