Dynamics of accommodation: measurements for clinical application.

Accommodation dynamics have not been used in clinical diagnosis as have eye movement and pupillary dynamics; the difficulty of clinical observation is matched by limitations in measurement methods. An instrument suitable for clinical use is described that allows measurement of step response latencies and especially time constants. With computer analysis, phase plane trajectories, and noise spectra can be quickly obtained also. The utility of these dynamical parameters for clinical diagnosis is illustrated by a study of changes of time constants with age in prepresbyopia.