Table 2 quantitatively compares anatomic relationships of the IO among subject groups. Statistical comparisons are omitted for the blepharoplasty without hypertropia group, which contains only two subjects. The IO was 0.49 ± 1.50 mm anterior to globe center in the hypertropic eye of the blepharoplasty group, but 0.55 ± 1.02 mm posterior in controls (
P = 0.043) and even farther posterior at 0.80 ± 0.70 mm in the blepharoplasty without hypertropia group. The IO centroid was 15.79 ± 1.38 mm below globe center in the hypertropic eyes of the blepharoplasty group, significantly farther inferior than in controls at 14.69 ± 0.76 mm (
P = 0.004) or the blepharoplasty without hypertropia group at 14.35 ± 1.03 mm. The AP distance from IO center to the inferior orbital rim was approximately 1 mm less at 5.08 ± 2.40 mm in the hypertropic eyes of the blepharoplasty group than in the control group at 6.17 ± 1.83 mm (
P = 0.046) and less still than in the blepharoplasty without hypertropia group at 6.96 ± 0.94 mm. The vertical distance between the IO center and the inferior orbital rim was also approximately 1 mm less at 5.31 ± 1.58 mm in the hypertropic eyes of the blepharoplasty group than in the control group at 6.42 ± 1.42 mm (
P = 0.045), and also less than in the blepharoplasty without hypertropia group at 6.50 ± 0.25 mm. The horizontal distance from the lower eyelid skin surface to the anterior IO border was approximately 1.75 mm less in the hypertropic eyes of the blepharoplasty group at 6.81 ± 1.96 mm than controls at 8.65 ± 1.34 mm (
P = 0.002) and the blepharoplasty without hypertropia group at 8.10 ± 2.84 mm. However, none of the foregoing variables in the other hypertropia group differed significantly from controls. For example, the AP distance from globe center to IO center was 0.55 ± 1.50 mm in the other hypertropia group and 0.54 ± 1.05 mm in the control group (
P = 0.087). The vertical distance from the globe center to the IO center in the other hypertropia group was −14.69 ± 0.76 mm, not significantly different from the −15.10 ± 0.84 mm-distance in controls (
P = 0.099). Neither of the foregoing variables differed significantly between controls and the hypotropic fellow orbits in the blepharoplasty group. Notable differences were observed between hypertropic and hypotropic fellow orbits in the blepharoplasty group. As illustrated by the example in
Figures 2B and
2C and summarized numerically for all subjects in
Table 3, the IO centroid was farther anterior and inferior in the hypertropic than in hypotropic fellow eyes in central gaze. In hypertropic orbits, the IO centroid was 0.49 ± 1.02 mm anterior to globe center, while in hypotropic fellow orbits the IO centroid was 0.63 ± 1.26 mm posterior (
P = 0.032). The vertical position of the IO centroid was 15.79 ± 1.38 mm below globe center in the hypertropic orbits, significantly farther inferior than in hypotropic fellow orbits at 14.57 ± 0.72 mm (
P = 0.013). The anterior IO border was approximately 1.3 mm closer to the lower eyelid skin in hypertropic orbits at 6.81 ± 1.96 mm than hypotropic fellow orbits at 8.12 ± 1.23 mm (
P = 0.042). However, none of the foregoing variables differed between hypertropic and hypotropic fellow orbits in the other hypertropia group.