To characterize regional variations in orbital morphology between populations from Southern China and Kashi through three-dimensional computed tomography (3D-CT) measurements, providing anatomical references for clinical practice.

In this observational cross-sectional study, patients from Zhongshan Ophthalmic Center (Southern China group) and the First People’s Hospital of Kashi (Kashi group) were analyzed using Mimics Research software. And 24 orbital parameters were measured, including orbital volume, retroorbital fat, extraocular muscle volume, and various orbital dimensions.

A total of 160 eyes from 80 participants were included, with each center enrolling 40 participants, comprising 20 males and 20 females. The mean age was 42.75±10.83y (range, 25–58) in the Southern China male group, 48.35±13.04y (range, 21–76) in the Southern China female group, 42.40±17.05y (range, 21–76) in the Kashi male group, and 43.05±13.52y (range, 19–74) in the Kashi female group. No significant differences were observed in orbital volume or medial orbital depth (P>0.05). The Southern China group had greater orbital height (35.98±1.66 vs 34.83±1.88 mm; P=0.005), higher orbital index (95.55±6.59 vs 91.91±4.72; P=0.006), and larger exophthalmos (16.60±2.15 vs 15.49±1.81 mm; P=0.014), while the Kashi group had smaller sphenoid trigone length (11.25±3.14 vs 12.64±3.19 mm; P=0.033) and width [7.43 (3.02) mm vs 8.83 (3.26) mm; P=0.016]. These differences were mainly observed in males. All 3D-CT measurements showed excellent interobserver reliability (ICC=0.95–0.99).

This study reveals distinct regional variations in orbital anatomy between the Southern China and Kashi populations. Participants from Southern China exhibit greater orbital height, orbital index, and exophthalmos, whereas those from Kashi show smaller sphenoid trigone dimensions. These findings provide valuable anatomical references for orbital decompression, fracture reconstruction, and radiological diagnosis.