Abstract
Purpose::
To evaluate the growth of the bony orbit as a function of age.
Methods::
In this cross-sectional study, 49 nonconsecutive patients without known orbital, ocular, or cranial pathology were evaluated using computerized tomography (CT) of the orbit. Ten measurements of length were made for each orbit (medial and lateral orbit length, medial to lateral angle, orbit axis to midline angle, globe diameter and protrusion, anterior vertical and horizontal orbital diameter, and maximal vertical and horizontal orbital diameter). Four measurements required interorbital comparison (lateral interorbital distance, anterior medial and maximal medial orbital distance, and interorbital axis angle). AGFA Web1000 version 4.1 software was used to review the scans and make measurements. Paired groups t-tests were used to compare the orbits for symmetry. Method pooled Student’s t-tests were used to compare genders. ANOVAs were used to evaluate differences of ethnicity. Pearson correlations were computed.
Results::
Of the 49 patients’ scans included, 28 were white, 9 African-American, 7 Hispanic, and 5 "Other." There were 18 females and 31 males. Age ranged from 3 days to 73.92 years old: 28 patients younger than 17 years, and 21 older than 17. There were no differences between most right and left orbital measurements, though differences were noted in medial to lateral angle, central axis angle, and medial length (p<0.0001, <0.0001, & 0.0364, respectively). All right and corresponding left measurements were significantly correlated (p≤0.0162). With the exception of right central axis angle (p=0.1739), all orbital measurements were significantly correlated with ipsilateral globe diameter and globe protrusion (p≤0.0462). In review of CTs of subjects at least 17 years old, only right vertical anterior and vertical maximal diameter were different among included ethnic groups (p=0.0054, 0.0153, respectively). Males at least 17 years old had bilaterally longer lateral interorbital distances and horizontal anterior and horizontal maximal diameters compared with females (p=0.0258, 0.0028, 0.0028, respectively), while females had a wider interorbital angle (p=0.0169). Scatter plots with smoother lines demonstrated rapid early change which slowed with older age in all bony variables, while orbital and interorbital axes showed a slow, steady change as a function of age.
Conclusions::
Growth of the normal orbit proceeds symmetrically, with few differences between genders and relatively none among different ethnicities. The greatest and most rapid changes in orbital dimensions occur in the first few years of life and are highly correlated to globe development.
Keywords: orbit • anatomy