Visual Attention Effects on Multifocal Pupillographic Responses

Abstract

Purpose: : Multifocal pupillography perimetry has recently been developed and refined for visual field assessment of glaucoma. This study explored for the first time the possible presence of attention-related changes to the amplitudes of pupillary constriction.

Methods: : Two experiments were carried out: the second to verify the findings of the first. In both experiments both white and yellow stimuli were examined. In Experiment 1 (19 subjects) the stimuli had a maximum luminance of 288cd/m². Other experiments showed that those stimuli might drive the pupillary responses into a saturating range so in Experiment 2 (22 subjects) the stimuli had maximum luminance of 150 cd/m² stimuli. In the attention task noted changes in the shape of the fixation target pressing a button whenever a change occurred. In all experiments the multifocal array contained 44 stimulus regions extending to 30 deg eccentricity; the stimulus elements were presented for 33 ms at a mean rate of 44/s/eye. Each protocol was divided into eight segments of 30 s.

Results: : Attention reduced the amplitude of the transient pupil responses to white stimuli (Exp 1: -1.58dB, p=0.0001; Exp 2: -0.20dB p=0.021) but increased responses to yellow stimuli (Exp 1: 1.15dB, p=0.006; Exp 2: 1.71dB p=0.054). A naso-temporal bias was possibly shown in Exp 2, in which at the ( p<=0.1) level 6 nasal regions, as opposed to one temporal region, had their responses suppressed during attention protocols using white stimuli.

Conclusions: : Pupillary responses were found to be significantly influenced by attention, albeit equivocally, as contrasting reactions were obtained in response to white and coloured stimuli. The result was verified in the second experiment.

Keywords: perimetry • pupil • pupillary reflex