[Feature extraction and pupil size detection of pupillary light reflex in opiate addicts].

An effective algorithm for detecting pupil size based on image processing was established. Three features reflecting differences between opiate addicts and normal subjects in pupillary light reflex were extracted by applying this algorithm, including absolute amplitude of contraction (AAC), relative amplitude of contraction (RAC) and slope of contraction velocity (SCV). Effects of addiction, sex, myopia, aging, sleep deprivation on the three features were studied.