Quantifying interactions between accommodation and vergence in a binocularly normal population

Sweeney, Laura E.; Seidel, Dirk; Day, Mhairi; Gray, Lyle S.

doi:10.1016/j.visres.2014.10.007

Cited by 17 publications

(8 citation statements)

References 55 publications

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“…With exit pupil diameters of 0.5 mm or smaller, the human accommodation system is open looped [Ripps et al 1962;Ward and Charman 1987]. Under these conditions, it has been shown that the accommodative distance of the eyes will naturally follow the vergence distance [Fincham and Walton 1957;Sweeney et al 2014;Tsuetaki and Schor 1987].…”

Section: Disparity-driven Accommodationmentioning

confidence: 99%

Accommodation-invariant computational near-eye displays

et al. 2017

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Fig. 1. Conventional near-eye displays present a user with images that are perceived to be in focus at only one distance (top left, 1 m). If the eye accommodates to a different distance, the image is blurred (top left, 0.3 m and ∞). A point spread function (PSF) illustrates the blur introduced for a single point of light at each distance (insets). The fact that conventional near-eye displays have a single sharp focus distance can be problematic, because it produces focus cues that are inconsistent with a natural 3D environment. We propose a computational display system that uses PSF engineering to create a visual stimulus that does not change with the eye's accommodation distance (bottom left). This accommodation-invariant display mode tailors depth-invariant PSFs to near-eye display applications, allowing the eye to accommodate to arbitrary distances without changes in image sharpness. To assess the proposed display mode, we build a benchtop prototype near-eye display that allows for stereoscopic image presentation (right). An autorefractor is integrated into the prototype to validate the accommodation-invariant display principle with human subjects. Although emerging virtual and augmented reality (VR/AR) systems can produce highly immersive experiences, they can also cause visual discomfort, eyestrain, and nausea. One of the sources of these symptoms is a mismatch between vergence and focus cues. In current VR/AR near-eye displays, a stereoscopic image pair drives the vergence state of the human visual system to arbitrary distances, but the accommodation, or focus, state of the eyes is optically driven towards a fixed distance. In this work, we introduce a new display technology, dubbed accommodation-invariant (AI) near-eye displays, to improve the consistency of depth cues in near-eye displays. Rather than producing correct focus cues, AI displays are optically engineered to produce visual stimuli that are invariant to the accommodation state of the eye. The accommodation system can then be driven by stereoscopic cues, and the mismatch between vergence and accommodation state of the eyes is significantly reduced. We validate the principle of operation of AI displays using a prototype display that allows for the accommodation state of users to

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Section: Disparity-driven Accommodationmentioning

confidence: 99%

Accommodation-invariant computational near-eye displays

et al. 2017

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“…The targets used for the measurements of the CA/C ratio were two fusible black crosses with two nonfusible monocular cues (point) to check for the absence of monocular suppression. The high spatial frequency targets reduced the size of the Panum area and prevented inaccurate vergence responses, inducing some variability in the CA/C ratio as observed by Sweeney et al 38 The accommodative loop was opened. Participants were instructed to indicate when the two crosses were fused while the monocular points were simultaneously viewed.…”

Section: Assessment Proceduresmentioning

confidence: 93%

Stereoscopic Viewing Can Induce Changes in the CA/C Ratio

Neveu¹,

Roumes²,

Philippe³

et al. 2016

Invest. Ophthalmol. Vis. Sci.

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Citation: Neveu P, Roumes C, Philippe M, Fuchs P, Priot A-E. Stereoscopic viewing can induce changes in the CA/C ratio. Invest Ophthalmol Vis Sci. 2016;57:4321-4326. DOI:10.1167/ iovs.15-18854 PURPOSE. Stereoscopic displays challenge the neural cross-coupling between accommodation and vergence by inducing a constant accommodative demand and a varying vergence demand. Stereoscopic viewing calls for a decrease in the gain of vergence accommodation, which is the accommodation caused by vergence, quantified by using the convergenceaccommodation to convergence (CA/C) ratio. However, its adaptability is still a subject of debate.METHODS. Cross-coupling (CA/C and AC/A ratios) and tonic components of vergence and accommodation were assessed in 12 participants (27.5 6 5 years, stereoacuity better than 60 arc seconds, 6/6 acuity with corrected refractive error) before and after a 20-minute exposure to stereoscopic viewing. During stimulation, vergence demand oscillated from 1 to 3 meter angles along a virtual sagittal line in sinusoidal movements, while accommodative demand was fixed at 1.5 diopters. RESULTS.Results showed a decreased CA/C ratio (À10.36%, df ¼ 10, t ¼ 2.835, P ¼ 0.018), with no change in the AC/A ratio (P ¼ 0.090), tonic vergence (P ¼ 0.708), and tonic accommodation (P ¼ 0.493).CONCLUSIONS. These findings demonstrated that the CA/C ratio can exhibit adaptive adjustments. The observed nature and amount of the oculomotor modification failed to compensate for the stereoscopic constraint.Keywords: accommodation, vergence, CA/C, stereoscopic viewing A ccommodation and vergence are neurologically crosscoupled and interact dynamically, so that an accommodative stimulus induces both accommodative and vergence responses-and vice versa for a vergence stimulus. The vergence evoked by accommodation, known as accommodative vergence, can be quantified by using the AC/A ratio, which assesses the amount of vergence per unit change in accommodation. The accommodation induced by vergence, known as vergence accommodation, can be quantified by using the CA/C ratio, which measures the amount of accommodation per unit change in vergence. Different static and dynamic models of the accommodative and vergence systems have been proposed to provide an understanding of the organization and the interaction between the two systems.

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“…This factor makes assessing interactions between the accommodative and vergence systems 22 without the use of additional measurement instruments impossible. 23 Researchers are also limited in conducting essential data quality control checks using eye position, such as validating that a participant fixated a given stimulus during recording.…”

Section: Introductionmentioning

confidence: 99%

Validation of the PowerRef 3 for Measuring Accommodation: Comparison With the Grand Seiko WAM-5500A Autorefractor

Gehring

Haensel

Curtiss

et al. 2022

Trans. Vis. Sci. Tech.

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Purpose This validation study examines the PowerRef 3 as a method for measuring accommodation objectively. We assess agreement with refractive measurements obtained simultaneously by the Grand Seiko WAM-5500A autorefractor. Methods Refractive measurements were recorded simultaneously using the PowerRef 3 and WAM-5500A in 32 noncyclopleged participants aged 15 to 46 years. Accommodative states were recorded for 10 seconds at six accommodative demands (5 diopters [D], 4 D, 3 D, 2.5 D, 2 D, and 0 D) while participants fixated a high-contrast Maltese cross. WAM-5500A measurements were converted to power in the vertical meridian for comparison with PowerRef 3 data. Dioptric difference values were computed, and agreement was assessed using Bland-Altman plots with 95% limits of agreement (LOA) and intraclass correlation coefficient analyses. Results The mean absolute dioptric differences measured 0.14 D or less across accommodative demands. Analyses showed an excellent intraclass correlation coefficient across the tested demands (0.93). Bland–Altman plots indicated a bias of −0.02 D with 95% LOA of −1.03 D to 0.99 D. The 95% LOA was smallest for the 3 D demand (−0.71 D to 0.64 D), and largest at 5 D demand (−1.51 D to 1.30 D). Conclusions The mean dioptric differences between the PowerRef 3 and WAM-5500A autorefractor were small and not clinically significant. While some variability in agreement was observed depending on the tested demand, the PowerRef 3 demonstrated good agreement with the WAM-5500A. Translational Relevance The PowerRef 3 may be used to obtain objective measures of accommodation both monocularly and binocularly and provides a more flexible method, especially in pediatric populations.

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Quantifying interactions between accommodation and vergence in a binocularly normal population

Cited by 17 publications

References 55 publications

Accommodation-invariant computational near-eye displays

Accommodation-invariant computational near-eye displays

Stereoscopic Viewing Can Induce Changes in the CA/C Ratio

Validation of the PowerRef 3 for Measuring Accommodation: Comparison With the Grand Seiko WAM-5500A Autorefractor

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