Comparative Study of Axial Length Estimation using A-Scan Ultrasound and Carl-Zeiss IOI Master in Benin City, Edo State, Nigeria

Abstract

Axial length of the human eye is the distance from the anterior pole of the cornea to the posterior retina pole. It is an important element in evaluating the eye’s power of refraction. Innovations and advances in technology have greatly increased accurate measurements of axial length in the previous two decades.  This study compared axial length measurements using A-scan ultrasound and the Carl Zeiss IOL master’s in human eyes in order to ascertain their repeatability and reliability. This research employed a cross-sectional design to study 80 eyes of participants aged 40 -- 80 (63+/-10.1) years selected using purposive random sampling techniques in two ophthalmology clinics located in Benin City, Edo State, Nigeria. SPSS version 23.0 was used to analyze the data. The independent-sample T-test and Pearson’s correlation coefficient were used to compare axial length and determine relationship between both instruments, respectively. Statistically significant level was taken as probability values P ˂0.05. The average axial length recorded by A-scan Ultrasound was 23.54mm ± 1.25 SD, and Carl Zeiss IOL Master was 23.62mm ± 1.25 SD. There was no significantly remarkable difference between average axial length recorded with both instruments (p = 0.7). Both Carl Zeiss IOL Master biometric instrument and the A-scan ultrasound biometric instrument could be used to measure axial length interchangeably only when there are no factors that negatively affect any of the instrument’s results.