Duration of pupillary constriction in response to a photographic flash.

摘要

We read with interest the recent article by Twa et al. concerning the clinical measurement of pupil diameter (PD) using digital flash photography. Although not explicitly stated, it appears that the authors' intention was to measure the dark-adapted pupil diameter (DAPD) at < 1 lux and at 5 lux. Digital photography was performed with the Nikon CoolPix 990 camera using the auto-flash setting at 17 cm. First, a 10-second infrared video clip was taken followed by a flash photograph; the subject was allowed to readapt for 2 minutes, and then another examiner repeated the video and photograph. It is unlikely that the second digital photograph was taken exactly 2 minutes and 10 seconds after the first one, but the interval between them was not measured.