Vergence driven accommodation with simulated disparity in myopia and emmetropia

• Published in: Experimental eye research 2018-01, Vol.166, p.96-105
• Main Authors: Maiello, Guido, Kerber, Kristen L., Thorn, Frank, Bex, Peter J., Vera-Diaz, Fuensanta A.
• Format: Article
• Language: English
• Subjects: Accommodation; Accommodation, Ocular - physiology; Adolescent; Adult; Analysis of Variance; Convergence, Ocular - physiology; Emmetropia - physiology; Female; Humans; Male; Myopia; Myopia - physiopathology; Refraction, Ocular - physiology; Refractive error; Vergence; Virtual reality; Young Adult
• ISSN: 0014-4835; 1096-0007
• DOI: 10.1016/j.exer.2017.10.004

The formation of focused and corresponding foveal images requires a close synergy between the accommodation and vergence systems. This linkage is usually decoupled in virtual reality systems and may be dysfunctional in people who are at risk of developing myopia. We study how refractive error affects vergence-accommodation interactions in stereoscopic displays. Vergence and accommodative responses were measured in 21 young healthy adults (n=9 myopes, 22–31 years) while subjects viewed naturalistic stimuli on a 3D display. In Step 1, vergence was driven behind the monitor using a blurred, non-accommodative, uncrossed disparity target. In Step 2, vergence and accommodation were driven back to the monitor plane using naturalistic images that contained structured depth and focus information from size, blur and/or disparity. In Step 1, both refractive groups converged towards the stereoscopic target depth plane, but the vergence-driven accommodative change was smaller in emmetropes than in myopes (F1,19=5.13, p=0.036). In Step 2, there was little effect of peripheral depth cues on accommodation or vergence in either refractive group. However, vergence responses were significantly slower (F1,19=4.55, p=0.046) and accommodation variability was higher (F1,19=12.9, p=0.0019) in myopes. Vergence and accommodation responses are disrupted in virtual reality displays in both refractive groups. Accommodation responses are less stable in myopes, perhaps due to a lower sensitivity to dioptric blur. Such inaccuracies of accommodation may cause long-term blur on the retina, which has been associated with a failure of emmetropization. •Vergence and accommodation are disrupted in virtual reality systems.•Vergence-driven accommodation is stronger in myopes than in emmetropes.•In myopes vergence is slower and accommodation is less stable.•Accommodation inaccuracy causes retinal blur, which may be associated with myopia.