Accommodation and pupil responses to random-dot stereograms

Abstract

We investigated the dynamics of accommodative and pupillary responses to random-dot stereograms presented in crossed and uncrossed disparity in six visually normal young adult subjects (mean age = 25.8 ± 3.1 years). Accommodation and pupil measures were monitored monocularly with a custom built photorefraction system while subjects fixated at the center of a random-dot stereogram. On each trial, the stereogram initially depicted a flat plane and then changed to depict a sinusoidal corrugation in depth while fixation remained constant. Increase in disparity specified depth resulted in pupil constriction during both crossed and uncrossed disparity presentations. The change in pupil size between crossed and uncrossed disparity conditions was not significantly different (p > 0.05). The change in pupil size was also accompanied by a small concomitant increase in accommodation. In addition, the dynamic properties of pupil responses varied as a function of their initial (starting) diameter. The finding that accommodation and pupil responses increased with disparity regardless of the sign of retinal disparity suggests that these responses were driven by apparent depth rather than shifts in mean simulated distance of the stimulus. Presumably the need for the increased depth of focus when viewing stimuli extended in depth results in pupil constriction which also results in a concomitant change in accommodation. Starting position effects in pupil response confirm the non-linearity in the operating range of the pupil.

Stimuli Characteristics and Psychophysical Requirements for Visual Training in Amblyopia: A Narrative Review

“…Usually, random-dot stimuli are used for stereoacuity assessment in clinical practice, but recent published works showed their application also in improving stereopsis values in amblyopia [ 16 , 54 ]. The use of a random-dot stereogram entails a cortical activation in the early visual cortex, particularly with mixed-polarity stimulus [ 61 ], and a small but significant activation of the pupil and accommodation responses [ 62 ]. Additionally, the optimal size of the dots should be considered for well-designed random-dot stimuli, since the literature suggests that larger dots implicate better stereo-perception [ 63 ].…”

Stereopsis assessment at multiple distances with an iPad application

“…This would improve the speed of vision screenings by performing the ST test at distance and assuming the absence of visual acuities poorer than 0.1 logMAR without conducting a visual acuity test. Myopic refractive errors could be easily detected with ST at distance even though hyperopia may go undetected because the subject might accommodate like with a visual acuity test (Suryakumar and Allison 2015). Hess et al, with a similar random dot stereotest, also reported a loss in stereopsis with the reduction in visual acuity (Hess et al 2016).…”