[Natural history of intermittent exotropia--statistical study of preoperative strabismic angle in different age groups].

To clarify the natural history of intermittent exotropia, the authors statistically analysed the size of deviations between the initial and the last visit of unoperated intermittent exotropes. In younger patients who were followed for over five years, the magnitudes were almost the same throughout the follow-up periods. A statistical analysis of preoperative strabismic angles in operated cases of different age groups was also done. From comparable studies of the preoperative size of exodeviations in three different age groups, the deviations in distance fixation in adults were apparently larger than in children. We think the size of the deviation in distance fixation tends to increase with aging, but the increase was not so great for the older adult group. However, the size of the deviation in near fixation tended to steadily increase throughout aging, showing statistical significance among all three groups, children, adults in their twenties and thirties, and adults over forty. In the over forty group, the convergence insufficiency type of deviation was present in the majority.