AIM: To compare the ciliary body thickness between eyes with primary angle closure (PAC) and primary angle-closure glaucoma (PACG) with the normal eyes, and to investigate the association between ciliary body thickness and ciliary processes situation. METHODS: In this cross-sectional study, 57 patients with PAC/PACG were matched to 57 normal subjects after propensity score matching (PSM) adjusting for age and gender. All subjects underwent conventional ocular examinations and ultrasound biomicroscopy (UBM) examination, among which the patients with PAC/PACG performed the examinations one month after laser peripheral iridotomy (LPI). Quantitative parameters were measured, which included ciliary body thickness at the position of 1 mm posterior to the scleral spur (CBT1), trabecular-ciliary process distance (TCPD) and trabecular-ciliary process angle (TCA). RESULTS: Eyes with PAC/PACG presented significantly thinner CBT1, shorter TCPD and smaller TCA (P<0.001) than the normal eyes, both in comparison of the means of four quadrants and in comparisons of each quadrant. After removing images with peripheral anterior synechia (PAS), the same results were also found in comparisons between the two groups. Significant correlations were found between TCPD (R2=0.537, P<0.001) and TCA (R2=0.517, P<0.001) with CBT1. CONCLUSION: Eyes with PAC/PACG have thinner ciliary body thickness and more anteriorly situated ciliary processes. Thinner ciliary body thickness is associated with anterior situation of the ciliary processes.