Ultrasound Contact Biometry with and without pupil dilation.

Abstract

Purpose: To evaluate the difference in ultrasonic biometric measurements and intraocular lens power calculation before and after pupil dilation. Methods: In this prospective cohort case series, contact ultrasonic biometry measurements before and after pupil dilation were performed on 118 eyes, at the cataract pre-surgery clinic. The parameters compared were axial length (AL), corneal power (mean K) and the corresponding intraocular lens (IOL) power which was calculated using the SRK/T formula. Paired sample t-test was applied. Confidence interval of 95% with α of 0.05 was taken. Results: This study found statistically no significant difference in pre- and post-dilation calculated IOL power (p=0.507). However, statistically there was significant difference between K-reading, anterior chamber depth, lens thickness and axial lengths (p<0.008). Vitreous length did not show any difference on dilatation of pupil (p= 0.051). Conclusion: This study demonstrates that there is no statistically and clinically significant effect of pupil dilation on biometry measurements for intraocular lens power calculations using SRK/T formula, though significant changes may be noted in K-reading, anterior chamber depth, lens thickness and axial lengths.