To judge the feasibility of virtual reality (VR) headsets for vision testing and treatment of binocular vision disorders and low vision, angular resolution (logMAR) and field of view must be known and may not be reliably provided. This is the first study to measure the limitations of VR systems for eye care applications.
This study aimed to measure, in a sample of VR headsets, lens power and other physical and optical characteristics needed to calculate minimum angular resolution in logMAR and field of view in determining feasibility for vision applications.
Lens power and horizontal display size were measured, and logMAR, field of view, and maximum convergence demand were calculated for two standalone VR devices, Oculus Rift DK2 and HTC Vive, and, for four smartphone VR headsets, Zeiss VR1, Samsung Gear VR, VR Box, and SunnyPeak, each paired with four high-resolution smartphones, Samsung Galaxy S7/S8, iPhone X, and LG VR30.
On average, the smallest letter that could be displayed in VR was 0.55 ± 0.17 (20/71), ranging from 0.79 (20/123) in the DK2 to 0.28 (20/39) in SunnyPeak with S7. Mean field of view was 67.1 ± 18.0°, ranging from 39.6° in the SunnyPeak with S7 to 85.6° in the HTC Vive. The mean field of view when used as a low vision aid was 30.8° and 16.9° for 2.2× and 4×, respectively. The mean maximum near convergence demand produced for a 60-mm interpupillary distance was 68.2 ± 32.9Δ.
The minimum angular resolution in logMAR of current VR technology is insufficient for visual acuity testing and may be insufficient for standalone treatment of amblyopia. Field of view may be less than that reported by manufacturers but adequate for some types of visual field testing and similar to existing telescopic low vision aids. Use for vergence testing and training is a concern for headsets with long eye-to-screen distance when interpupillary distance <60 mm.