Direct measurement of the horizontal and vertical ciliary sulcus placements using ultrasound biomicroscopy in myopic eyes

Purpose: To investigate the spatial placements of the horizontal and vertical ciliary sulcus through ultrasound biomicroscopy (UBM) analysis. Setting: Eye and ENT Hospital of Fudan University, Shanghai, China. Design: Prospective observational clinical study. Methods: This study comprised 82 eyes of preoperative implantable collamer lens (ICL) candidates with myopic ICL. UBM was used to measure the ciliary sulcus-to-sulcus (STS), central distance from endothelium to STS (ASL) crystalline lens to STS (STSL), the angle-to-angle distance (ATA), and anterior chamber depth (ACD) to crystalline lens in both the horizontal and vertical orientations. Mean keratometry, axial lengths, and horizontal white-to-white distance were also recorded. Results: The mean ASL was 3.574 ± 0.183 and 3.725 ± 0.198 mm, while the mean STSL was 0.488 ± 0.175 and 0.629 ± 0.161 mm in the horizontal and vertical orientations, respectively ( P < .001). The vertical STSL (vSTSL) exceeded the horizontal STSL (hSTSL) by a mean difference of 0.141 ± 0.128 mm, and similarly, the vASL exceeded the hASL by a mean difference of 0.151 ± 0.137 mm. Both the hSTSL and vSTSL showed a negative correlation with ACD ( P < .001). The difference in STSL (vSTSL − hSTSL) was positively correlated with vSTSL, vASL, and the difference in STS (all P < .05) and negatively correlated with hSTSL and hASL (both P < .05). Conclusions: The ciliary sulcus is typically located more posteriorly in the vertical orientation than in the horizontal orientation.