Correlation of anterior chamber angle and ciliary sulcus diameters with white-to-white corneal diameter in high myopes using artemis VHF digital ultrasound.

PURPOSE: To determine whether horizontal angle diameter and sulcus diameter can be accurately estimated by conventional external measurements in high myopic eyes.

METHODS

Ten horizontal anterior segment scans were obtained with the Artemis 1 very high-frequency (VHF) digital ultrasound arc-scanner in 40 eyes of 20 patients. Angle and sulcus diameters were measured and descriptive statistics and within-eye repeatability were calculated. Linear regression was performed between each permutation of white-to-white, angle diameter, and sulcus diameter. Multivariate regression also included anterior chamber depth (ACD), age, manifest refraction, keratometry, and central corneal thickness (CCT). The standard deviation and 95% confidence interval (CI) of the residuals were calculated.

RESULTS

The population mean +/-standard deviation (95% CI) was 12.88 +/- 0.42 mm [12.74, 13.02] for angle diameter and 12.85 +/- 0.69 mm [12.63, 13.07] for sulcus diameter. Within-eye repeatability was 0.13 mm for angle diameter and 0.23 mm for sulcus diameter. A weak correlation was noted between white-to-white and angle diameter (r2=0.59) with a 95% CI of +/-0.53 mm. Multivariate regression found white-to-white, CCT, and minimum keratometry predicted angle diameter (r2=0.69) with a 95% CI of +/-0.46 mm. For predicting sulcus diameter, there were weak correlations between white-to-white (r2=0.32) with a 95% CI of +/-1.11 mm and angle diameter (r2=0.46) with a 95% CI of +/-0.99 mm. Multivariate regression found angle diameter and ACD predicted sulcus diameter (r2=0.57) with 95% CI of +/-0.88 mm.

CONCLUSIONS

Regression modeling found weak correlations among all combinations of white-to-white, angle diameter, and sulcus diameter. Given the relative accuracy of direct measurement of angle and sulcus diameter compared to the potential accuracy of these regression equations, it appears that direct measurement would increase the safety of anterior and posterior chamber phakic intraocular lens sizing.