Abstract
Stereopsis plays an important role in everyday visuomotor tasks. However, abnormal visual experience during development may result in reduced or absent stereopsis. In recent years, laboratory methods have been designed to strengthen stereopsis in adults with abnormal binocular vision. However, these techniques require many trials and are often not engaging. Video games can be used to tackle these challenges. Several studies have reported benefits of using video games to improve both low- and high- level visual functions in the treatment of amblyopia. Furthermore, with recent commercialization of Virtual Reality (VR), depth cue scaffolding has become possible in this approach. Our aim was to test whether depth cue scaffolding in VR can be used to train stereo-anomalous observers to rely on disparity cues.
We designed two VR games to train stereovision. Strabismic deviations were corrected using a virtual prism and dichoptic calibration sight, and input to the two eyes was perceptually balanced by reducing the luminance to the dominant eye. Thus, avoiding diplopia and/or suppression. One game required participants to launch a dart when a dartboard, moving in depth, was on the same depth plane as the dart. The other game required participants to destroy the nearest of several targets moving forward. Importantly, initially the games provided multiple cues for judging depth (shadows, perspective, motion parallax, and disparity). As participants progressed through the game, we selectively removed cues (shadows, perspective and motion parallax), finally leaving only disparity cues.
Results show that most stereo deficient participants improved in the game, and several showed transfer to both clinical and psychophysical stereoacuity tests (Ding & Levi, 2011). Overall, participants with anisometropia reached a lower stereoacuity threshold at a faster rate compared to participants with strabismus.
We conclude that cue scaffolding may be a useful tool for recovering stereopsis in adults with abnormal visual development.