[Correlation between white-to-white diameter and ciliary sulcus diameter of high myopia eyes]

To investigate the ciliary sulcus diameters in horizontal and vertical axes and to analyze the correlation between white-to-white diameter and horizontal ciliary sulcus diameter for high myopia eyes at different anterior chamber depths.

IOL-Master was used to measure white-to-white diameters and anterior chamber depths of 108 high myopia eyes and verified by digital caliper. Based on the depth of central anterior chamber not including corneal thickness, the testing eyes were divided into three groups: shallow AC group (3.0 mm < ACD ≤ 3.2 mm), medium AC group (3.2 mm < ACD ≤ 3.4 mm), and deep AC group (ACD > 3.4 mm). Furthermore, the horizontal and vertical ciliary sulcus diameters were checked by full-scale 50-Hz ultrasound biomicroscopy. The data of three AC groups were analyzed separately. The paired sample t-test was used to compare: white-to-white diameters and horizontal sulcus diameters, horizontal and vertical suclus diameters. The correlations between white-to-white diameters and horizontal sulcus diameters were assessed using linear regression analysis. The difference in the three groups of white-to-white diameters and ciliary sulcus diameters were compared by Student Newman Keuls test.

The mean diameters and standard deviations of WTW diameters and horizontal ciliary sulcus diameters in the shallow AC group was, respectively, (11.46 ± 0.38) and (11.57 ± 0.32) mm(t = -2.849, P = 0.007). Linear regression analysis found a statistically significant correlation between white-to-white diameters and horizontal sulcus diameters with a coefficient of determinant of 0.797 (P = 0.000). The mean vertical suclus diameters was (12.27 ± 0.48) mm. The difference between horizontal and vertical suclus diameters was statistically significant (t = -15.522, P = 0.000) . The mean diameters and standard deviations of WTW diameters and horizontal ciliary sulcus diameters in the medium AC group was, respectively, (11.58 ± 0.31) and (11.77 ± 0.26) mm. (t = -4.523, P = 0.000). Linear regression analysis found a statistically significant correlation between white-to-white diameters and horizontal sulcus diameters with a coefficient of determinant of 0.639 (P = 0.000). The mean vertical suclus diameters was (12.52 ± 0.37) mm. The difference between horizontal and vertical suclus diameters was statistically significant (t = -13.987, P = 0.001) . The mean diameters and standard deviations of WTW diameters and horizontal ciliary sulcus diameters in the medium AC group was, respectively, (11.68 ± 0.22) and (11.91 ± 0.23) mm (t = -5.157, P = 0.000). Linear regression did not reveal horizontal sulcus diameters were a significant predictor of white-to-white diameters with a coefficient of determinant of 0.253 (P = 0.126). The mean vertical suclus diameters was (12.69 ± 0.36) mm. The difference between horizontal and vertical suclus diameters was statistically significant (t = -18.433, P = 0.000) .

The white-to-white diameter measuring technique is not identical to the horizontal diameter of the ciliary sulcus and the potential difference between them is increased with deepening anterior chamber depth. Our preliminary study illustrated that the ciliary sculus is not circular and a vertical diameter is longer than horizontal one.