Effect of apparent depth cues on accommodation in a Badal optometer

Otero, Carles; Aldaba, Mikel; Martínez-Navarro, Beatriz; Pujol, Jaume

doi:10.1111/cxo.12534

Cited by 6 publications

(6 citation statements)

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“…First, this is not a natural task: Even though Experiment 2 kept within the 'zone of clear single binocular vision', two subjects (BB and RE) had to be excluded because they experienced diplopia from the outset, whilst one subject (SR) experienced diplopia midway through the experiment, and her remaining trials had to be rescheduled. As we have already noted, subjects struggle to accommodate accurately in a Badal system when accommodation is manipulated merely as an optical reflex (Charman & Heron, 2015), and there is increasing evidence that cognitive cues to distance are required for effective accommodation (Gwiazda, Thorn, Bauer, & Held, 1993;Otero, Aldaba, Martínez-Navarro, & Pujol, 2017). The same may well be true when vergence and accommodation are manipulated using purely optical cues.…”

Section: Discussionmentioning

confidence: 84%

Do We See Scale?

Linton¹

2018

Preprint

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The visual system is supposed to extract distance information from the environment in order to scale the size and distance of objects in the visual scene. The purpose of this article is to challenge this account in three stages: First, I identify three shortcomings of the literature on vergence as our primary cue to near distances. Second, I present the results from two experiments that control for these shortcomings, but at the cost of eradicating vergence and accommodation as effective distance cues (average gain of y = 0.161x + 38.64). Third, I argue that if all our cues to distance are either (a) ineffective (vergence; accommodation; motion parallax), (b) merely relative (angular size; diplopia), or (c) merely cognitive (familiar size; vertical disparity), then the visual system does not appear to extract absolute distance information, and we should be open to the possibility that vision functions without scale.Keywords: vergence, accommodation, visual distance, visual scale, visual cognition IntroductionScale has two components: size and distance. Specifically, it is concerned with differentiating a small object up close from a large object far away, even though both may have the same visual angle. Ptolemy (c.160 AD) first articulated visual scale in these terms, arguing that size wasn't just a function of visual angle (vs. Euclid, c.300 BC), but visual angle appropriately scaled by distance information (see Hatfield, 2002). But the problem is where does the distance information come from? Ptolemy could rely on 'extramission': the length of the rays emitted, and then returning, to the eye. As an 'intromission' theorist, al-Haytham (c.1021) had no such luxury and relied on familiar size instead. But Descartes (1637) regarded familiar size as a merely cognitive cue and so, along with Kepler (1604), outlined three optical / physiological cues that could plausibly replace Ptolemy's 'extramission' thesis: 1. vergence (the angles of the eyes), 2. accommodation (the curvature of the intraocular lens), and 3. motion parallax (the change in the visual scene from the motion of the observer). (which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/371948 doi: bioRxiv preprint first posted online 2 VergenceThe visual system's ability to extract distance information from vergence was one of visual psychophysics' earliest concerns, and was answered affirmatively by Hueck (1838) (2001) presented subjects with a small 0.57° disc in darkness for 5s, then after 5s in complete darkness asked subjects to match a visible reference to the disc's distance.They found subjects were close to veridical between 20cm and 40cm, but distances were increasingly underestimated beyond that: 60cm was judged to be 50cm, and 80cm judged to be 56cm. Nonetheless, they concluded that their results were consistent with , at least in reaching space: '…the results of our experiment indicate that vergence can be u...

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Section: Discussionmentioning

confidence: 84%

Do We See Scale?

Linton¹

2018

Preprint

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“…shadows and relative target size in half of the trials) were removed from the targets. Previous research has found that stimuli that are lacking in distance cues do not properly stimulate accommodation ( 18 ). While accommodation in HMD-mediated VR is disturbed regardless of distance cues ( 8 ), the lack of distance cues could have elicited accommodative responses which differ from accommodative responses that normally occur in HMD users.…”

Section: Discussionmentioning

confidence: 99%

The pupil near response is short lasting and intact in virtual reality head mounted displays

Pielage¹,

Zekveld²,

Ven³

et al. 2023

JEMR

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The pupil of the eye constricts when moving focus from an object further away to an object closer by. This is called the pupil near response, which typically occurs together with accommodation and vergence responses. When immersed in virtual reality mediated through a head-mounted display, this triad is disrupted by the vergence-accommodation conflict. However, it is not yet clear if the disruption also affects the pupil near response. Two experiments were performed to assess this. The first experiment had participants follow a target that first appeared at a far position and then moved to either a near position (far-to-near; FN) or to another far position (far-to-far; FF). The second experiment had participants follow a target that jumped between five positions, which was repeated at several distances. Experiment 1 showed a greater pupil constriction amplitude for FN trials, compared to FF trials, suggesting that the pupil near response is intact in head-mounted display mediated virtual reality. Experiment 2 did not find that average pupil dilation differed when fixating targets at different distances, suggesting that the pupil near response is transient and does not result in sustained pupil size changes.

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“…Additionally, the lack of appropriate accommodation cues can significantly alter the overall accommodative response when stimulated optically. 24 This may become relevant in the clinical monocular accommodation facility flipper test, where there are no disparity cues and blur cues do not match vergence, i.e., blur changes while the size-distance cue does not. 41 The neural cross-linkages between vergence and accommodation, that are subject to adaptive regulation, 42 may have played a role in the results of our study, as disparity is an important cue for distance.…”

Section: Discussionmentioning

confidence: 99%

“…The accommodative target used for all conditions was a 2º high-contrast black Maltese cross on a white uniform background (figure 1B), with an average luminance of 3.7 cd/m 2 and 56.2 cd/m 2 for the black and white regions, respectively. Even though this stimulus does not have peripheral depth cues, which could have improved the accommodative response, 24,25 it is the most frequently used stimulus for accommodation studies due to its wide frequency spectrum 26 and it is easily reproducible. The use of this stimulus allows direct comparisons of our results with previous studies of dynamic accommodation.…”

Section: Instrumentation and Stimulimentioning

confidence: 99%

Stimulus Unpredictability in Time, Magnitude, and Direction on Accommodation

et al. 2019

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SIGNIFICANCE The effect of predictability in changes of time, magnitude, and direction of the accommodation demand on the accommodation response latency and its magnitude are insignificant, which suggests that repetitive accommodative tasks such as the clinical accommodative facility test may not be influenced by potential anticipation effects. PURPOSE The purpose of this study was to investigate the effect of stimulus' time, magnitude, and direction predictability, as well as their interactions, on accommodation latency and response magnitude. METHODS Monocular accommodative response and latency were measured in 12 young subjects for nine different conditions where the stimulus accommodative demand changed several times in a steplike fashion for a period of 120 seconds. Each change in accommodative demand could have different time duration (i.e., 1, 2, or 3 seconds), magnitude (1, 2, or 3 diopters), and/or direction (i.e., accommodation or disaccommodation). All conditions were created permuting the factors of time, magnitude, and direction with two levels each: random and not random. The baseline condition was a step signal from 0 to 2 diopters persisting for 2 seconds in both accommodative demands. After each condition, subjects were asked to provide a score from 1 to 5 in their perceived predictability. RESULTS Friedman test conducted on the perceived predictability of each condition resulted in statistically significant differences between the nine conditions (χ2 = 56.57, P < .01). However, repeated-measures analysis of variance applied to latency and accommodative response magnitude did not show significant differences (P > .05). In addition, no correlation was found between the perceived predictability scores and both latency and accommodative response magnitudes between the most predictable and the most unpredictable conditions. CONCLUSIONS Subjects were able to perceptually notice whether the stimulus was predictable or not, although our results indicate no significant effect of stimuli predictability on either the accommodation latency or its magnitude.

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Effect of apparent depth cues on accommodation in a Badal optometer

Abstract: Background:To analyze the effect of peripheral depth cues on

Cited by 6 publications

References 31 publications

Do We See Scale?

Do We See Scale?

The pupil near response is short lasting and intact in virtual reality head mounted displays

Stimulus Unpredictability in Time, Magnitude, and Direction on Accommodation

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