Abstract
Purpose:
To study the changes in the opening angle of the optic nerve and angle of the ocular orbit with increasing age in normal Japanese children.
Methods:
We studied 147 normal children whose ages ranged from 6 months to 18 years who had undergone computed tomography(CT) as a diagnostic procedure. Measurements were done on the axial CT images that included the entire optic nerves of both eyes. The opening angle of the optic nerve was defined as the angle formed by the intersection of a line running through the left optic nerve and a vertical line passing through the center of the nose. The opening angle of the orbit was defined as the angle formed by the intersection of a line running tangentially along the deep lateral wall of left orbit and a vertical line passing through the center of the nose. The relationships between the age and these opening angles were analyzed by regression analysis.
Results:
The correlation between the age and the opening angle of the optic nerve was not significant. The opening angle of the orbit decreased relatively rapidly until about 2-3 years of age, and then it stabilized. The decrease in the opening angle of the orbit with increasing age was significant(P<0.001). The relationship between these two parameters was best fit by a logarithmic regression curve.
Conclusions:
Because the Opening angle of the orbit decreased significantly with increasing age, this factor must be considered when diagnosing and treating strabismus in children.