PUPILLARY HIPPUS: AN UNRECOGNIZED EXAMPLE OF BIOLOGIC CHAOS

Abstract

We analyzed the pupil size vs time from six subjects using pupilography and nonlinear techniques. The correlation dimensions ranged from 4.08 to 5.7. The Hurst exponents ranged from 0.132 to 0.546. All data sets contained at least one positive Lyapunov exponent. The use of surrogate yielded statistically significant differences for the correlation dimension. Phase space analysis yields a definite flow, and in subject two, period-doubling is evident. The accumulated evidence supports the notion that dynamics of pupil size are governed by deterministic chaos rather than a stochastic or linear process. This implies that one might discern between well and disease states using pupillography and that the dynamics can be mechanistically modeled.