Comparison of Swept-Source Optical Biometry and Contact A-Scan Ultrasonography for Axial Length Measurement in Eyes with Mature Cataract

OBJECTIVES: The objectives are to compare axial length (AL) measurements obtained using swept-source optical biometers and contact A-scan ultrasonography (USG) in eyes with mature cataract, and to evaluate inter-device agreement and acquisition success rates.
METHODS: This retrospective cross-sectional study included eyes with clinically defined mature cataract. AL measurements were obtained using two swept-source optical devices (Tomey - OA and Heidelberg Anterion) and contact A-scan USG (Tomey UD-800), all performed on the same day by a single examiner. Inter-device comparisons, Bland–Altman agreement analyses, and intraclass correlation coefficients (ICC) were calculated. Optical measurement failure rates were recorded.
RESULTS: AL measurements were successfully obtained with both optical biometers in 50 eyes. AL values showed strong agreement between the Tomey - OA OA-2000 and Anterion, with no significant inter-device difference. In contrast, contact A-scan USG yielded significantly shorter AL measurements compared with both optical devices (mean difference approximately 0.26–0.30 mm). Optical biometry failed to obtain AL measurements in approximately one-third of eyes with mature cataract. Inter-method reliability for AL was high (ICC >0.90).
DISCUSSION AND CONCLUSION: Swept-source optical biometers provide consistent and interchangeable AL measurements in eyes with mature cataract when measurements are obtainable. However, optical acquisition failure remains common in advanced cataracts, highlighting the continued clinical relevance of A-scan USG. The systematic tendency of contact ultrasound to produce shorter AL measurements should be considered during intraocular lens power calculation.

Keywords: A-scan ultrasonography, axial length, intraocular lens power calculation, mature cataract, swept-source optical biometry