The purpose of this study is to measure the range of normal eye movement and to evaluate the effect of age on the range of ocular movement in a normal population.

We conducted a prospective observational study of 85 subjects aged between 5 and 91 years. Photographs were taken of the cardinal position, and these images were analyzed using an image analysis software (Adobe Photoshop 6.0, Adobe, San Jose, CA, USA). To measure the range of eye movement, the preprocessed images were analyzed using the Image J program. The range of movement of the eyeball was quantitatively measured using corneal limbal analysis. Specifically, the ranges of ocular movement according to adduction, abduction, elevation, and depression were measured.

The normal movement ranges were 44.4 ± 6.9° in adduction, 44.8 ± 5.5° in abduction, 27.7 ± 7.6° in elevation, and 46.7 ± 8.4° in depression. Adduction, abduction, and elevation were negatively correlated with age (R² = 0.220, R² = 0.126, and R² = 0.304, respectively, all p < 0.001). However, there was no significant correlation between age and depression (R² = 0.030, p = 0.113).

For all ages, the range of normal ocular movement in the horizontal direction was symmetric, while the range of ocular movement in elevation was smaller than that of depression. As age increased, the range of ocular movement decreased in all directions except depression, but depression did not decrease with age. When assessing eye movement, it is necessary to consider the range of ocular movements relative to both the movement direction and changes in the ocular movement range according to age.