Figure 6.

Exotropia at near and distance. The eye trackers were calibrated at distance; 0 degrees refers to fixation at 305 cm. A, Task 1: Spontaneous episodes of right exotropia (amplitude 15.0 degrees, peak velocity 20.1 degrees/second) in a 46-year-old man during fixation at 305 cm. B, Task 2: Exotropia (amplitude 14.2 degrees, peak velocity 24.5 degrees/second) after shutter occlusion of the right eye, while fixating on a crosshair at ~21 cm from the left eye along its line of sight with a distant laser spot. The intent was to mimic the eye movement in (A), by moving the right eye from −15.0 degrees to 0 degrees. The crosshair may have been placed a few centimeters closer than intended, resulting in a movement of the right eye from −18.1 degrees to −3.9 degrees. C, Task 3: Gaze shift along left eye’s line of sight from a crosshair nominally at 21 cm to a laser spot at 305 cm resulted in an outward movement of the right eye (amplitude 18.1 degrees, peak velocity 142.2 degrees/second) that combined divergence with a disconjugate saccade. Replication of the right eye’s movement in (B) was intended, but was foiled by the occurrence of a saccade. D, Task 4: Same task as (C), except that when the distant laser spot appeared, a shutter simultaneously covered the right eye. The right eye moved outward (amplitude 33.0 degrees, peak velocity 43.4 degrees/second) from −17.4 degrees to 15.3 degrees, to assume the same final position as in (A).