The Effect of Anticipation on the Transfer Function of the Human Lens System

Wildt, G. J. van der; Bouman, M. A.; Kraats, Jan van de

doi:10.1080/713818858

Cited by 49 publications

(50 citation statements)

References 10 publications

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“…There have, however, been several reports that have indicated that chromatic cues are not vital to accommoReprint requests to: D. I. Flitcroft, St. Mary's Hospital Medical School, Norfolk Place, London W2 1PG, England dation control (Stark & Takahashi, 1965;Troelstra et al, 1964;Van der Wildt et al, 1974). It should be noted that these studies used only small numbers of subjects, and as reported by Fincham a sizeable proportion of subjects can accommodate successfully in the absence of chromatic cues.…”

Section: Introductionmentioning

confidence: 84%

A neural and computational model for the chromatic control of accommodation

Flitcroft¹

1990

Vis Neurosci

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Accommodation is more accurate with polychromatic stimuli than with narrowband or monochromatic stimuli. The aim of this paper is to develop a computational model for how the visual system uses the extra information in polychromatic stimuli to increase the accuracy of accommodation responses. The proposed model is developed within the context of both trichromacy and also the organization of spatial and chromatic processing within the visual cortex.The refractive error present in the retinal image can be estimated by comparing image quality with and without small additional changes in refractive state. In polychromatic light, the chromatic aberration of the eye results in differences in ocular refractive power for light of different wavelengths. As a result, the refractive state of the eye can be estimated by comparing image quality in the three types of cone photoreceptor. The ability of cortical neurons to perform such comparisons on image quality with a crude form of spatial-frequency analysis is examined theoretically. It is found that spatially band-pass chromatically opponent neurons (that may correspond to double opponent neurons) can perform such calculations and that chromatic cues to accommodation are extracted most effectively by neurons responding to spatial frequencies of between 2 and 8 cycles/deg.

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Section: Introductionmentioning

confidence: 84%

A neural and computational model for the chromatic control of accommodation

Flitcroft¹

1990

Vis Neurosci

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“…Each amplitude took 30 s to complete (Figure 2). An unpredictable movement was included between amplitudes to prevent the subject from continuing on to make predictive eye movements at the frequency of the stimulus during the next, smaller amplitude stimulus (van der Wildt, Bouman, & van de Kraats, 1974). A complete trial took approximately 1 min 45 s, and proceeded continuously after it started, regardless of the attention of the subject.…”

Section: Methodsmentioning

confidence: 99%

Sensitivity of vergence responses of 5- to 10-week-old human infants

2016

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Infants have been shown to make vergence eye movements by 1 month of age to stimulation with prisms or targets moving in depth. However, little is currently understood about the threshold sensitivity of the maturing visual system to such stimulation. In this study, 5- to 10-week-old human infants and adults viewed a target moving in depth as a triangle wave of three amplitudes (1.0, 0.5, and 0.25 meter angles). Their horizontal eye position and the refractive state of both eyes were measured simultaneously. The vergence responses of the infants and adults varied at the same frequency as the stimulus at the three tested modulation amplitudes. For a typical infant of this age, the smallest amplitude is equivalent to an interocular change of approximately 2° of retinal disparity, from nearest to farthest points. The infants' accommodation responses only modulated reliably to the largest stimulus, while adults responded to all three amplitudes. Although the accommodative system appears relatively insensitive, the sensitivity of the vergence responses suggests that subtle cues are available to drive vergence in the second month after birth.

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“…In adults, 1.75 D of defocus or 1.75 MA of disparity can drive accommodation and vergence responses without requiring significant extra-retinal cues (e.g., a sense of target proximity; Fincham, 1951; Schor, Alexander, Cormack, & Stevenson, 1992; Schor, Wood, & Ogawa, 1984; Toates, 1972). Multiple target speeds were used to minimize the potential for predictive responses (Stark, 1968; van der Wildt, Bouman, & van de Kraats, 1974). No systematic difference in performance was noted across different target speeds and therefore the responses from all three target speeds were pooled during analyses.…”

Section: Methodsmentioning

confidence: 99%

Cues for the control of ocular accommodation and vergence during postnatal human development

2008

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Accommodation and vergence help maintain single and focused visual experience while an object moves in depth. The relative importance of retinal blur and disparity, the primary sensory cues to accommodation and vergence, is largely unknown during development; a period when growth of the eye and head necessitate continual recalibration of egocentric space. Here we measured the developmental importance of retinal disparity in 192 typically developing subjects (1.9 months to 46 years). Subjects viewed high-contrast cartoon targets with naturalistic spatial frequency spectra while their accommodation and vergence responses were measured from both eyes using a PowerRefractor. Accommodative gain was reduced during monocular viewing relative to full binocular viewing, even though the fixating eye generated comparable tracking eye movements in the two conditions. This result was consistent across three forms of monocular occlusion. The accommodative gain was lowest in infants and only reached adult levels by 7 to 10 years of age. As expected, the gain of vergence was also reduced in monocular conditions. When 4- to 6-year-old children read 20/40-sized letters, their monocular accommodative gain reached adult-like levels. In summary, binocular viewing appears necessary under naturalistic viewing conditions to generate full accommodation and vergence responses in typically developing humans.

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The Effect of Anticipation on the Transfer Function of the Human Lens System

Cited by 49 publications

References 10 publications

A neural and computational model for the chromatic control of accommodation

A neural and computational model for the chromatic control of accommodation

Sensitivity of vergence responses of 5- to 10-week-old human infants

Cues for the control of ocular accommodation and vergence during postnatal human development

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