New research published in the Indian Journal of Ophthalmology assessed the efficacy of amblyopia treatment via a smartphone-based anaglyph video run in virtual reality (VR) mode among adult patients.
Give me some background first.
Treating amblyopia with a VR anaglyphic method relies on showing the two eyes two different, but similar, images that are designed to overlap and create a single image.
However, some elements are missing for each eye.
Go on…
This virtual reality vision therapy (VRVT) requires that there are main active elements presented to the amblyopic eye—but not to the non-amblyopic eye—so the amblyopic eye needs to play an active role in binocular vision to see the complete image.
The display used in this study (viewable here) consisted of a VR headset, a demo VR video downloaded from YouTube, and red and blue filters.
Now, talk about the study.
In this non-randomized prospective interventional study, a total of 10 patients (mean age of 20.5 years) diagnosed with anisometropic amblyopia underwent 4 hours of VRVT per day for 6 months.
The research team evaluated the following at three visits (initial, 3 months, and 6 months):
- Best-corrected visual acuity (BCVA)
- Stereoacuity
- Near point of accommodation
- Contrast acuity
How was anisometropic amblyopia defined?
Anisometropic amblyopia was defined when the difference in spherical equivalent between two eyes was 1.0-1.5 D (anisohyperopia) or more and 3.0-4.0 D or more (anisomyopia).
Amblyopia was noted as an interocular difference of 0.2 log units or greater using the crowded logMAR acuity test.
Findings?
The mean BCVA in amblyopic eyes improved significantly from a logMAR value of 0.73±0.64 before VRVT to a post-training VRVT value of 0.48±0.44 (P<0.01).
Interestingly, 8 of 10 patients experienced an improvement in stereoacuity, with the mean stereoacuity changed from a value of 560±301.158 initially to 263±143.58 seconds of arc after VRVT (P<0.01).
Anything else?
The average accommodation decreased from 15±7.40 at presentation to 12.60±6.10 cm after training (P<0.01).
Finally, the mean contrast acuity increased from 1.21±0.72 before VRVT to 1.52±0.49 log unit following training.
Limitations?
Three key limitations of the study included:
- Sample size
- Long-term stability of amblyogenic factors following treatment
- Changes in parameters after discontinuing VRVT
The study authors noted that further studies are necessary to identify an optimal protocol for implementing VRVT and to confirm the validity, reliability, and outcomes of this treatment.
Take home.
A smartphone-based anaglyph video system using VRVT is an effective treatment approach for anisometropic amblyopia in adults, the authors concluded.
While most special software-based treatments are costly and inaccessible, developing a therapy that utilizes smartphones may make it easier to disseminate this therapy, they stated.