A quasistatic study of pupil and accommodation after-effects following near vision.

The study examines the effect of a near task on immediate post-task measures of pupil size and accommodative state. The method of quasistatic measurement of accommodation was used and pupillary changes elicited by the accommodative stimulus were simultaneously recorded using an infrared video-pupillometer. This method requires a short (typically 2 minutes) but strong (up to 10 D in most subjects) near-vision effort, with the accommodative and pupillary responses being recorded before, during, and after the task. The results show pupil after-effects to be more pronounced than tonic accommodative after-effects. Inter-individual difference in after-effects is large. The pupil after-effect was dissociated from the tonic accommodation after-effect and lasted in some cases for more than 15 minutes. The pupil after-effect was not masked by darkness. It is proposed that monitoring the changes of pupil is valuable when assessing the after-effects of sustained near vision.