Three-dimensional analysis of dentist's eye movements.

We measured the eye movements of a dentist while a pediatric patient walked toward a dental chair. Bilateral eye movements were measured and analyzed three-dimensionally based on the angle of convergence. The frequency of fixation points registered in each test ranged from 2 to 11, with an average of 6.6. No significant differences were observed when the experiments were grouped according to the age of the observed child. In 13 out of 74 experiments, the calculated distances between the observer and the fixation points corresponded to the actual distances. According to the patterns of where the fixation points occurred, 13 experiments had an "inside-outside" pattern and 61 had an "outside-only" pattern. None of the experiments had an "inside-only" pattern. The "outside-only" group was further subclassified into 50 "behind-only" patterns, 5 "in front-only" patterns, and 6 "in-front-and-behind" patterns. As far as depth perception is concerned, the angle of convergence determined by the eye movements would rarely correspond to the actual distance between the observer and the fixation point.