Abstract :
Introduction: Cataract surgery demands refractive accuracy. To achieve this, accurate biometry is required. So two biometry methods should be compared for accuracy.
Aim: To compare accuracy of immersion USG and optical biometry with reference to AXL measurement and postphaco refraction.
Materials and Methods: 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.
Results: 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}.
Conclusion: 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.
Keyword :
Cataract, Emmetropia, Intraocular lens, Visual acuity.