Assessing the Validity and Repeatability of a Portable A-scan Ultrasound Device in Sitting and Supine Positions

Abstract

Engineering and Technology: 2nd Place (The Ohio State University Denman Undergraduate Research Forum)Background: Accurate ocular biometry is essential for intraocular lens power calculation in cataract surgery1, monitoring myopia management therapies2, estimating pulsatile ocular blood volume3, and ensuring high-resolution retinal imaging4. This study evaluated the validity and inter- and intra-observer variability of a portable a-scan ultrasound device for measuring axial length (AL) in sitting and supine positions compared to the IOLMaster optical biometer, the clinical standard. Methods: Fifty-one healthy adults (mean age = 26 ± 10 years; 67% female) participated in two study sessions. AL measurements of the right eye were obtained first with the IOLMaster optical biometer (Zeiss) in the sitting position, followed by the portable a-scan ultrasound (Scanmate A, DGH Technology) in both sitting and supine positions. Measurements were repeated in the second session by two observers. Five measurements were averaged for the optical biometer and three for the a-scan device. Data were analyzed using paired t-tests for inter-device comparisons and repeated-measures ANOVA for intra- and inter-observer variability, with significance set at α = 0.05. Results: The IOLMaster optical biometer measured significantly longer AL (24.2 ± 1.8 mm) compared to the a-scan ultrasound (23.7 ± 1.7 mm, p < 0.001). No significant differences were observed between sitting and supine positions for either device. Additionally, both devices demonstrated excellent intra-observer and inter-observer variability with no significant differences between measurements. Conclusion: While the optical biometer measured longer AL values, the portable a-scan ultrasound device showed high reliability with consistent measurements across observers and positions. Its portability and accuracy make it a practical tool for clinical settings, particularly in resource-limited environments lacking access to optical biometers.No embargoAcademic Major: Medical Anthropolog