Normal Range of Eye Movement and Its Relationship to Age

Abstract

Purpose : To determinethe range of eye movement in normal human subjects and to investigate the effect of age on eye movement.

Methods : A prospective observational study. We enrolled 261 healthy subjects, 5 to 91 years of age. Photographs were obtained in the cardinal gaze positions and processed using Photoshop. The processed images were analyzed using the Image J program to measure the angle of eye movement.The angle of eye movement was quantified using a modified limbus test.

Results : The normal ranges of eye movement were 44.9±7.2° in adduction, 44.2±6.8° in adduction, 27.9±7.6° in elevation, and 47.1±8.0° in depression. There were significant negative correlations between the angles of horizontal and upward gazes and age (R=-0.294 in adduction, R=-0.355 in abduction, and R=-0.506 in elevation, all P<0.001). However, the angle of downward gaze was not significantly correlated with age (R=0.017, P=0.722).

Conclusions : The normal ranges for the angle of horizontal gaze were symmetric, whereas therange of upward gaze angle was smaller than that for the downward gaze among all ages. Unlike the age-related decline of range in other gazes, only downward gaze was not impaired by increasing age. Differencesineye-movement range based ongaze direction and their associated aging mechanisms should be considered when assessing eye movements.