Research on virtual reality (VR) technology and how it relates to vision is growing. Read literature below on how VR technology works in relation to our vision, the various effects VR has on vision, and how VR technology is used for patients that struggle with a vision disorder.
Virtual reality relies heavily on the concept of immersion. In regards to vision, binocular (both eye) and stereoscopic (depth perception) cues are critical to "trick" the visual system. Staring through a head mounted display is more or less like looking through a pair of binoculars except these binoculars provide you with a window into digital landscapes and worlds. The arrangement of having one lens per eye gives the user stereo vision, just as you would in real life. We humans use stereo vision to infer the depth and distance of objects
The clinical effects of watching a movie using a head-mounted virtual reality display were evaluated in sixty (60) subjects (age 13 to 18 years, average 14.7 years). Subjects viewed a movie using either a Samsung Gear VR device (30) or a 3-D movie outside of a head-mounted display (30). Evaluation of refractive error, angle of deviation (distance and near by cover test), and monocular near point of accommodation by push-up method was measured on all subjects before, immediately after, and 10-minutes after stimulation. Near stereoacuity was measured on all subjects before and immediately after stimulation.
Across both groups, no change in parameters was found to be statistically significant. Of interest, the VR cohort displayed a slight inware (eso) shift in ocular posture immediately after viewing (p = 0.06). Twelve (12) subjects in the 3-D movie group and 9 subjects in the VR group displayed some degree of myopic shift immediately after viewing. In the 3-D movie group, myopic shift resolved in 6.7 ± 10.9 minutes. In the VR group, myopic shift resolved in 4.8 ± 7.1 minutes. One patient in each group required up to 40 minutes to return to baseline. One subject in the VR group was unable to complete the study due to motion sickness and nausea.1
VR research also helps better understand how it is used to treat binocular disorders.
A pilot study utilized a binocular, head-mounted device used for dichoptic video watching as a proposed treatment for amblyopia. Twenty-seven (27) patients age 4-8 years participate in the study; 19 patients in the treatment arm (3 refractive amblyopic patients, 9 strabismic, 7 mixed amblyopia) and the remaining patients a sham group. Study subjects were assigned to watch dichoptic videos using the device for 60 minutes, 6 days per week for either 8 or 12 weeks. Patients were re-evaluated at 4, 8, 12, 24, and 36 weeks. At conclusion, mean VA improved by 0.26 logMAR (base VA for the cohort was 0.66 ± 0.2 logMAR) in the treatment group at 12 weeks. At 8 weeks, mean VA improved to 0.39 ± 0.160 logMAR; at 12 weeks to 0.39 ± 0.186 logMAR. At 24 weeks (following no treatment for 12 weeks) 15 patients retained a mean VA of 0.37 ± 0.167 logMAR. At 36 weeks (following no treatment for 24 weeks) 12 patients retained a mean VA of 0.43 ± 0.22 logMAR. Of note, 2 patients showed worse acuity from baseline at 36 weeks. The sham group was reassigned to treatment. After 4 weeks of treatment, mean VA improved 0.496 ± 0.24 logMAR. Average compliance was 88% ± 16% (100% compliance was defined as system use for the required time period for 6 days in a week; compliance was higher if the subject used the system on the rest day).2
A study of twenty-five (25) patients (8 male, 17 female; age 5-39 years (average 12.3), 16 children) with intermittent exotropia used a dichoptic virtual reality training program to improve eye positioning. Patients performed a training sequence twice daily for 10 minutes for a duration of 6 months. At the conclusion of the training program, 18 of the 25 subjects developed normal eye positioning (defined as alignment of less than or equal to 5 prism diopters of esophoria/tropia to less than or equal to 8 prism diopters of exophoria/tropia). Average eye position improved from 21.44 prism diopters (base-in) ± 13.25 prior to training to 7.2 prism diopters (base-in) ± 8.54 at conclusion. No adverse events were reported.3
Ten (10) participants underwent training with a novel virtual reality game used to treat convergence. Two participants from the VR group were lost to follow-up. Participants were to complete 180 minutes of training over the course of 3 weeks, and were compared to eight (8) patients that underwent a similar convergence training program using non-VR anaglyph treatment. Average compliance was 41% of the prescribed training time (64 minutes ± 45 minutes for the anaglyph group and 103 ± 76 minutes for the virtual reality game group). Vergence facility, positive fusional vergence, and first transient break and recover (vergence testing) improved in both groups and no adverse events were reported.4
A stereo training study reported a reduction in suppression in 10 of 11 of the adult subjects. Six subjects developed improved stereopsis and eight stereo deficient subjects reported improved reliance on stereoscopic rather than monocular depth cues. Six of 11 subjects displayed a slight increase in visual acuity (defined as > 0.04 logMAR); two of these subjects regressed and one subject was lost to follow-up. There were no reported adverse effects of VR-based stereo training.5
In brief, literature reports of use of VR for treatment of binocular vision disorders have reported a benefit to patients while simultaneously displaying no significant adverse events.
Vivid Vision’s VR activities work to reduce cortical suppression and to improve vergence range and stereopsis ability. The methods utilized within Vivid Vision’s software include dichoptic training and direct stereo training. Three independent studies have utilized Vivid Vision for the treatment of binocular vision disorders; the use of the software was, in all cases, at the discretion of the clinic/clinician(s) and primarily focused on use of dichoptic gameplay, rather than direct stereo vision training.
Seventeen (17) adult subjects (ages 17 to 69) with anisometropic amblyopia played two different dichoptic games using Vivid Vision software twice weekly for 8 weeks. Each session lasted 40 minutes. There were no adverse events reported. In the cohort, 47.1% had unmeasurable stereoacuity prior to treatment, while only 11.8% were found to have unmeasurable stereoacuity after training.6
The second independent assessment of the clinical efficacy of the Vivid Vision software examined thirty-four (34) patients (age 3 to 69 years) who were offered Vivid Vision when occlusion therapy was unsuccessful due to poor compliance, a plateau in treatment improvement, and/or regression in treatment. Subjects were diverse in age groups (<11yrs n=18, >11yrs n=16) and etiology of amblyopia (anisometropic n=25), combined aniso-strabismic n=5, strabismic n=4).
Participants completed a weekly 30-minute session with at least 3 tasks per session for 8 consecutive weeks (4 weeks for 3 participants). Dark filtering and blur filtering were applied to the non-amblyopic eye to allow 70-80% accuracy at the highest difficulty level throughout each session.
Significant improvement in amblyopic eye visual after treatment was observed in the full group, both age groups, and both etiology groups (p<0.0001). Randot stereoacuity improved in participants who had measurable stereopsis (n=15) at the start of treatment (p<0.05); no measurable improvement in stereoacuity was observed in the remaining participants. The conclusion of this independent assessment confirmed the favorable outcomes of treatment using the Vivid Vision software, especially for visual acuity. No adverse events were reported.7
The third independent study consisted of eighty-four (84) mild anisometropic amblyopia patients (age 18 to 53). Patients were allowed to play any of the four dichoptic games offered in the Vivid Vision software in any order for a total of one hour. Each patient completed eight (8) twice-weekly one-hour dichoptic gameplay sessions (total treatment time 8 hours). Fifty-six (56) percent of patients achieved an average improvement in Sloan best-corrected acuity by 0.16. Of interest, seventeen (17) percent of patients begin with Sloan best-corrected acuity of 0.9 or greater [better than Snellen 20/25 / LogMAR +0.1], which would limit the expected improvement in acuity. Patients were also not treated with any direct stereoscopic training—only dichoptic gameplay was offered. This improvement was significantly faster when compared to patching penalization, which requires upwards of 120 hours to achieve one line of acuity improvement. No adverse events were reported.8
Additional research relating to using VR with VR can also be found in Vivid Vision Publications, Presentations, and Awards