Assessment of the orbital structures using computed tomography in healthy adults

In this study, we retrospectively evaluated the orbital and ocular dimensions using computed tomography (CT) scans in healthy adults.

This retrospective study included 302 Turkish adult individuals aged 20-76 years (158 males and 144 females), who underwent paranasal sinus or craniofacial CT due to headache or suspicion of sinusitis, but abnormal orbital or cranial CT findings were not detected. Linear and volumetric measurements of the orbital structures were performed in the sagittal, coronal, and axial planes on CT slices. The volume was estimated in cubic centimeters using the equation of the ellipsoid method. A total of 34 parameters were measured from both eyes of each individual using 14 different anatomical landmarks and analyzed by gender and age.

Parameter values of orbital structures in males and females are shown in millimeters or cubic centimeters. In most of the 34 parameters that we evaluated, it was seen that males had statistically significant higher mean values than females (P < 0.05). Also, there was no statistically significant difference between the measurements of right and left orbits. The correlation with age was varied according to the 34 parameters. Interestingly enough, there were no statistically significant differences between the two genders for extraocular muscles thickness (except superior muscles group thickness-SMT) and left optic nerve thickness (LOT) (p > 0.05). The mean right superior muscles group thickness was 5.35 ± 0.85 mm in the male subjects and 4.64 ± 1.10 mm in the female subjects (P < 0.001). The mean left superior muscles group thickness (LSMT) was 5.28 ± 0.88 mm in the male subjects and 4.67 ± 1.16 mm in the female subjects (P < 0.001). The mean LOT was 6.15 ± 0.97 and 5.88 ± 1.07 mm in males and females, respectively (P = 0.099).

This study can be applied to the standardization of orbital morphometry in healthy adults.