Accommodation microfluctuations and pupil size during sustained viewing ofvisual display terminals

Accommodation microfluctuations comprise two dominant frequencies; a low fr equency component (LFC less than or equal to 0.6 Hz) and a high frequency c omponent (1.0 Hs < HFC < 2.1 Hz). In the present experiment we examine acco mmodation microfluctuations and steady-state pupil responses during sustain ed viewing of visual display terminals (VDTs). Steady-state accommodation a nd pupil responses were measured continuously and simultaneously using a mo dified Canon Autoref R-1 infra-red objective optometer and an Hamamatsu C31 60 Perceptscope Video Area Analyser. Measurements were obtained at three ti me intervals (0, 10 and 20 min) during a 20 min reading task presented on f ive different displays. With the displays placed at 50 cm, the task was to locate and identify typographical errors in one of five sets of standard te xt, Five young visually-normal emmetropic subjects with a mean age of 22.5 +/- 3.0 years participated in the study. Two-way ANOVA revealed no signific ant variation in the magnitude of the accommodation microfluctuations with either display or task duration, nor was there any significant interaction between these two factors. There was no significant variation in mean pupil diameter with either display or task duration. These measures may have the potential to provide objective information about visual display quality. ( C) 1999 The College of Optometrists. Published by Elsevier Science Ltd. All rights reserved.