Stereoacuity development in children with normal binocular single vision.

We made 344 stereoacuity determinations (Titmus Stereotest) on 321 children, ages 1 1/2 to 13 years, who had normal binocular single vision tested by other factors. The data showed a gradual improvement in stereoacuity scores with increasing age--up to age 9--when a normal stereoacuity of 40 seconds of arc was consistently found. The lower limits of stereoacuity compatible with normal binocular single vision were 3 1/2 years, 3,000 seconds; 5 years, 140 seconds: 5 1/2 years, 100 seconds; 6 years, 80 seconds; 7 years, 60 seconds; and 9 years, 40 seconds.