Correlation between ciliary sulcus diameter measured by 35 MHz ultrasound biomicroscopy and other ocular measurements

Purpose: To measure horizontal ciliary sulcus diameters by 35 MHz ultrasound biomicroscopy (UBM) and evaluate correlations between these and other ocular measurements. Setting: Department of Ophthalmology, Korea University College of Medicine, Seoul, Republic of Korea. Methods: A pilot group comprising 20 eyes of 10 patients was enrolled in a prospective trial. Horizontal sulcus diameter was measured using a 35 MHz UBM unit; other ocular measurements (eg, corneal curvature, refractive error, white-to-white [WTW] distance, anterior chamber depth [ACD]) were also taken in all patients. Linear regression analysis was used to evaluate the correlation between horizontal sulcus diameter and the other measurements. A regression equation was determined as a result of the analysis and applied to a second validation group (14 eyes). Results: The mean horizontal diameter of the ciliary sulcus in the pilot group was 11.56 mm ± 0.64 (SD). The mean corneal curvature was significantly and negatively correlated with the horizontal sulcus diameter (P<.001). Refractive error, ACD, and horizontal WTW diameter were not correlated with the horizontal sulcus diameter by multiple regression analysis. In the validation group, sulcus diameters estimated using the regression equation were significantly correlated with actual values, and these 2 sets of values were not statistically different. Conclusions: Mean corneal curvature was significantly and negatively correlated with horizontal sulcus diameter. The derived regression formula based on mean corneal curvature measurements may help predict sulcus diameters for proper sizing of posterior chamber phakic intraocular lenses.