COMPARATIVE STUDY OF AXIAL LENGTH ESTIMATION USING A-SCAN ULTRASOUND AND ZEISS IOL MASTER

ABSTRACT

Axial length of the human eye can be defined as the distance between the anterior corneal pole and the point within the retinal structure at the posterior pole. It is understood that the axial length of the eye is a key parameter in determining the refractive status. Technological advances in axial length measurement over the past two decades have increased accurately and improved greatly. The measurement of axial length is an essential tool that practitioners wishing to engage in refractive error management must have access to, Axial length estimation play an important role in the refractive status of the eye especially in different age groups, and this estimation is carried out using the optical or the non optical biometric instruments. In this study we determined the repeatability of axial length parameters using A-scan ultrasound and the zeiss IOLMaster. 80 eyes were used in this study, the data gotten from this research were Analysed and processed using the SPSS statistical package (version 23.0) where the repeatability between the measurements were first checked by the Bland-Altman method and then a comparison followed, it was discovered that Most of the participants in both groups (A-scan ultrasound and Zeiss IOL Master) had an axial length of approximately 23.0mm (figure 2a). The average axial length recorded by A-scan Ultrasound was 23.5 ± 1.2mm while that of Zeiss IOL Master was 23.6 ± 1.2mm (figure 2b). There was no significant difference between the average axial length recorded by the two instruments (p = 0.7). Both Carl Zeiss IOL Master biometric instrument and the A-scan ultrasound biometric instrument should be used to measure Axial length interchangeably only when there are no factors that negatively affect any of the instruments results, and in special cases like media opacity and vitreous hemorrhage A-scan ultrasound biometric instrument should be used.