Abstract
While spectacles have been around for centuries, relatively little is known about the perceptual and physical effects associated with the optical distortions they cause. Retinal image minification, for example, is caused by myopic spectacle correction and may also occur in wearable near-eye display systems such as augmented reality devices. Previous work suggests that having different amounts of minification (or magnification) between the eyes can produce perceptual distortions and oculomotor discomfort, but the extent to which these effects are noticeable and problematic during natural tasks is unknown. We sought to systematically identify the perceptual and physical effects experienced by naive observers when they initially wore spectacles that produced the same or different amounts of minification between the eyes. Forty participants wore spectacles that produced optical minification of 2% or 4% in both eyes, just one eye, or neither eye (control). After performing a naturalistic task that incorporated reading, interacting with objects, and visual search, participants reported on the physical and perceptual experiences associated with each pair. Overall, participants reported mild to moderate negative symptoms in all conditions other than the control, with greater effects associated with greater minification. However, contrary to the hypothesis that interocular image size differences are particularly problematic, participants ranked the monocular minifiers as only slightly more uncomfortable than their binocular counterparts. Additional experiment sessions were conducted to examine the effects associated with specific eye and head motions, which provided a potential explanation for these findings: participants experienced greater perceived motion with binocular minification as compared to monocular minification. This perceived motion is likely due to the disruption of the vestibulo-ocular reflex during head movements. These results emphasize the importance of studying the varied effects of optical distortions during natural tasks and can help develop guidelines for minimizing non-tolerance of corrective spectacles and near-eye displays.