Scaffolding depth cues and perceptual learning in VR to train stereovision: a proof of concept pilot study

Angelica Godinez,Oliver Ibarrondo,Dennis M Levi,Santiago Martín-González

doi:10.1038/s41598-021-89064-z

Angelica Godinez, Oliver Ibarrondo + Show 2 more

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https://doi.org/10.1038/s41598-021-89064-z

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Abstract

Stereopsis is a valuable feature of human visual perception, which may be impaired or absent in amblyopia and/or strabismus but can be improved through perceptual learning (PL) and videogames. The development of consumer virtual reality (VR) may provide a useful tool for improving stereovision. We report a proof of concept study, especially useful for strabismic patients and/or those with reduced or null stereoacuity. Our novel VR PL strategy is based on a principled approach which included aligning and balancing the perceptual input to the two eyes, dichoptic tasks, exposure to large disparities, scaffolding depth cues and perception for action. We recruited ten adults with normal vision and ten with binocular impairments. Participants played two novel PL games (DartBoard and Halloween) using a VR-HMD. Each game consisted of three depth cue scaffolding conditions, starting with non-binocular and binocular cues to depth and ending with only binocular disparity. All stereo-anomalous participants improved in the game and most (9/10) showed transfer to clinical and psychophysical stereoacuity tests (mean stereoacuity changed from 569 to 296 arc seconds, P < 0.0001). Stereo-normal participants also showed in-game improvement, which transferred to psychophysical tests (mean stereoacuity changed from 23 to a ceiling value of 20 arc seconds, P = 0.001). We conclude that a VR PL approach based on depth cue scaffolding may provide a useful method for improving stereoacuity, and the in-game performance metrics may provide useful insights into principles for effective treatment of stereo anomalies.This study was registered as a clinical trial on 04/05/2010 with the identifier NCT01115283 at ClinicalTrials.gov.

Highlights

Our rich perception of depth provides important information for navigation[1] and action[2,3]
Considering that the main drawbacks of laboratory-based training paradigms are participant compliance, attention and motivation, several authors have proposed the use of designed video games to treat amblyopia
We found statistically significant differences between the stereo-normal and stereo-anomalous groups in both pre- and post-analysis for all tests, except for the Dynamic Random-dot Stereogram test (DRS) small pre- treatment (P = 0.052) and DRS big post- treatment (P = 0.100)

Summary

Introduction

Our rich perception of depth provides important information for navigation[1] and action[2,3]. Depth perception is a complex process which requires the brain to integrate different visual c ues[4]. Of those cues, many require only one eye (non-binocular cues) and include overlapping (interposition), perspective (conical projection), lighting-shading, chromatic attenuation, focus and motion parallax (created by the relative motion between an observer’s head and the perceived scene). The leading cause of visual loss in children, is a neuro-developmental disorder arising from an imbalance between the ocular inputs to the visual p athway[10,11,12] It is characterized as reduced visual acuity in an otherwise normal eye despite best optical c orrection[13] and is typically secondary to misalignment of the visual axis (strabismus) and/or unequal refractive error (anisometropia). Several laboratory studies have reported benefits of using video games to treat amblyopia[34,35,36,37,38,39], including direct stimulation of s tereopsis[40]

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