Ultrasound Biomicroscopy (UBM plus, model P45, Paradigm(R)): Intraobserver Reproducibility and Agreement of Measurements

Purpose: To evaluate intraobserver reproducibility of measurements in images obtained by the ultrasound biomicroscopy (UBM plus, model P45, Paradigm, Inc., Utah, USA) and estimate the agreement of measurements by ultrasound biomicroscopy and A-scan ultrasound (model P37, Paradigm, Inc., Utah, USA). Methods: The anterior segment images of fifteen normal patients were obtained twice by single examiner. Six different parameters were measured in each image. Among the parameters, anterior chamber depth was compared with that measured by A-scan ultrasound. Results: The intraobserver reproducibility was high for all six parameters that includes central corneal thickness (coefficient of variation (%) 2.80), anterior chamber depth (coefficient of variation (%) 1.20), anterior chamber angle (coefficient of variation (%) 4.01), scleral thickness (coefficient of variation (%) 4.28), trabecular meshwork-iris distance (coefficient of variation (%) 6.09) and angle opening distance (AOD500, coefficient of variation (%) 6.09). The correlation between ultrasound biomicroscopy and A-scan ultrasound in measuring the anterior chamber depth was statistically significant (correlation coefficient = 0.79, p=0.002). Conclusions: The measurements of anterior segment parameters by ultrasound biomicroscopy have high reproducibility and will be useful in evaluating the anterior segment structure.