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

Purpos: To investigate the spatial placements of the horizontal and vertical ciliary sulcus through ultrasound biomicroscopy (UBM) analysis. Setting: EYE & ENT Hospital of Fudan University, Shanghai, China Design: Prospective observational clinical study. Methods: This study comprised 82 eyes of preoperative ICL candidates with myopic implantable collamer lens (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 ACD to crystalline lens (ACD-L) in both the horizontal and vertical orientations. Mean keratometry (Km), axial lengths (AL), and horizontal white-to-white distance (WTW) 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.