Abstract
Purpose :
The vergence-accommodation conflict is one of the main factors causing visual discomfort in virtual/augmented reality. The goal of this study was to investigate binocular accommodative response and visual performance with convergence changes when the two eyes had different extended depths of focus.
Methods :
Four normal subjects (26 ± 5 years of age) who could achieve at least 2 diopters (D) of accommodative response for 3D of demand were measured. A Maltese cross was presented through a binocular adaptive optics (AO) vision simulator to stimulate accommodation. Three optical conditions were generated: full AO correction (aberration-free), traditional monovision (TMV) with 1.5D of anisometropia, and modified monovision (MMV) with additional 4th-order and 6th-order Zernike spherical aberrations. Binocular accommodative responses were measured with different degrees of convergence ranging from 0 to 3D (meter angle) in steps of 1D. Binocular visual acuity and random dot stereoacuity were tested at 0.5, 1.0, and 2.0 c/deg sinusoidal corrugation spatial frequencies.
Results :
Both TMV and MMV increased binocular accommodation response compared to the AO condition. The change in average accommodative response at 3D convergence from 0D was 0.24 ± 0.21D with AO correction, 0.84 ± 0.51D with TMV, and 1.35 ± 0.30D with MMV (see figure). Accommodation with MMV was significantly larger than that with TMV (p<0.001). At 0D convergence, the average binocular visual acuity in LogMAR was -0.18 ± 0.04, -0.15 ± 0.04, and -0.07 ± 0.07 with AO correction, TMV, and MMV conditions respectively. MMV degraded visual acuity compared to AO condition (p<0.05) at 0D convergence. For all corrugation frequencies at 0D convergence, the average stereo detection thresholds in arcmins were 0.52 ± 0.22 with AO correction, 2.1 ± 0.86 with TMV (n=3, one subject was not measurable), and 0.87 ± 0.18 with MMV. Stereoacuity with MMV and AO correction surpassed that with TMV (p<0.05) at both 0 and 3D convergence.
Conclusions :
Modified monovision with spherical aberrations increases depth of focus, which allows for larger binocular accommodation changes with convergence, and yields a more natural vergence-accommodation relationship. Although binocular visual acuity and stereoacuity are slightly compromised, using modified monovision can alleviate the vergence-accommodation conflict in virtual/augmented reality.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.