A comparison of visual acuities obtained following biometry measurements by contact and immersion A-scan techniques

Abstract

Objectives: This study aimed to obtain and compare ocular biometry measurements in terms of axial length, anterior chamber depth, and lens thickness by contact and immersion ultrasound techniques of A-scan and compare postoperative results in terms of visual acuity and spherical refractive error obtained by each of these techniques. Materials and Methods: This study was a prospective cohort and a comparative study that was done on 188 eyes under evaluation for cataract surgery. Out of these, 94 eyes were evaluated for biometry measurements using the immersion technique, and the rest were evaluated using the contact technique. Intraocular lens (IOL) powers were calculated using each of the above biometry parameters, and postoperative visual outcomes were obtained in terms of visual acuity and spherical refractive error. Results of demographic, clinical, and biochemical characteristics were expressed as range, mean, and median. For qualitative data, the Chi-square test and for comparison, Students’ unpaired t-tests were used. TAQhe statistical software SPSS Statistics was used to analyze the data. Microsoft Office Word and Excel 2019 were used to generate graphs and tables. P<0.05 was considered as significant. Results: Visual acuity was significantly better in the patients who underwent IOL implantation whose power was calculated by the immersion method on the 1st postoperative day. However, there was no significant difference in the final corrected visual acuity. Spherical refractive error at the end of 1 month was significantly greater in patients who underwent IOL power calculation by the contact method as compared to the immersion method. Conclusion: The immersion method of A-scan gives a lesser refractive error postoperatively and is a more precise method of biometry, though there is no difference in the final visual acuity obtained by either of these methods.