Measurement of the anterior chamber depth and ocular axial length: transpalpebral B-mode ultrasound using an 18-MHz linear probe compared with the IOL Master 500.

<bold>Aims: </bold>To determine the reliability of transpalpebral ultrasound in B-mode (B-TUS) with a high-resolution linear probe (18 MHz) in estimating both the ocular anterior chamber depth (ACD) and axial length (AL), as well as its agreement with the IOL Master 500 optical biometer.<bold>Material and Methods: </bold>Cross-sectional study on 82 eyes of 41 volunteers with no history of eye disease. ACD and AL were determined using B-TUS and the IOL Master 500. The agreement between the two tech-niques and the variability of B-TUS (inter- and intra-observer) were analyzed with the Bland-Altman method. To this end, the mean difference between measures±1.96 SD was calculated to determine the limits of agreement (LoA).<bold>Results: </bold>The mean difference±1.96SD between B-TUS and the IOL Master 500 was -0.41±0.25mm for ACD (p<0.001) and -0.48±0.45 mm for AL (p<0.001). The maximum variability for B-TUS (average±1.96SD) was 0.00±0.35 mm at the inter-observer level for AL, and 0.00±0.18mm at the intra-observer level for AL.<bold>Conclusion: </bold>The determination of ACD and AL by B-TUS has a good re-liability and variability, in line with other sonographic techniques. However, it systematically provides smaller measurements than those obtained with the IOL Master 500, similar to the conventional ultrasound techniques. B-TUS could be useful in the assessment and follow-up of a wide range of ophthalmic diseases, in which a high accuracy in ACD and AL is not determinant. [ABSTRACT FROM AUTHOR]