Dynamic interactions between accommodation and convergence are velocity sensitive

doi:10.1016/0042-6989(86)90151-3

Vision Research

Volume 26, Issue 6, 1986, Pages 927-942

https://doi.org/10.1016/0042-6989(86)90151-3 Get rights and content

Abstract

Aftereffects of accommodation and vergence occur following approximately 1 min of adaptation to lenses and prisms respectively. This observation can be interpreted to mean that accommodation and vergence responses have phasic and tonic components. We have examined the role that these proposed subcomponents play in mutual interactions between accommodation and vergence. Both accommodative vergence (AV) and vergence accommodation (VA) were unresponsive to low temporal frequency variations (< 0. 1 Hz) in defocus and disparity respectively. However, both AV and VA were responsive to higher temporal frequency stimuli (up to 0.5 Hz). When negative feedback to the stimulated system was cancelled electronically, both AV and VA become responsive to low temporal frequency stimuli. The ratio or gain of accommodative vergence/accommodation (AC/A) and vergence accommodation/vergence (CA/C) increased nonlinearly with stimulus amplitude. Vergence aftereffects resulted from stimulation of AV and accommodative aftereffects resulted from stimulation of VA. These results are interpreted to mean there could be a complementary relationship between the amplitude of the AC/A ratio and proposed tonic adaptation of accommodation, and between the amplitude of the CA/C ratio and proposed tonic adaptation of vergence. A low saturation limit or stimulus window for tonic adaptation may account for the amplitude dependent nonlinearities of the AC/A and CA/C ratios.

References (36)

AlpernM. et al.
Vergence and accommodation: III proposed definitions of AC/A ratios
Am. J. Ophthal.
(1959)
BrodkeyJ. et al.
Feedback control analysis of accommodative convergence
Am. J. Surg.
(1967)
KrishnanV.V. et al.
Frequency analysis of accommodation, accommodative vergence and disparity vergence
Vision Res.
(1973)
SchorC.M.
The relationship between fusional vergence eye movements and fixation disparity
Vision Res.
(1979)
SchorC.M. et al.
Spatial tuning of static and dynamic local stereopsis
Vision Res.
(1984)
WestheimerG.
The Maxwellian view
Vision Res.
(1966)
WilsonD.
Noise coupling between accommodation and accommodative vergence
Vision Res.
(1973)
WilsonH.R.
Quantitative characterization of two types of line-spread functions near the fovea
Vision Res.
(1978)
BakerR. et al.
Time-course and variability of dark focus
Invest. Ophthal. visual Sci.
(1983)
CampbellF.W. et al.
Factors influencing accommodation responses of the human eye
J. opt. Soc. Am.
(1959)

CraneH.D. et al.

Ocular-focus stimulator

J. opt. Soc. Am.

(1970)

EbenholtzS.M.

Accommodative hysteresis: a precursor for induced myopia

Invest. Ophthal. visual Sci.

(1983)

FinchamE.F.

The accommodation reflex and its stimulus

Br. J. Ophthal.

(1951)

FinchamE.F. et al.

The reciprocal actions of accommodation and convergence

J. Physiol. Lond.

(1957)

FlomM.C.

On the relationship between accommodation and accommodative convergence. I Linearity

Am. J. Optom. Physiol. Opt.

(1960)

FryG.A.

A experimental analysis of the accommodation-covergence relations

Am. J. Optom. Arch. Am. Acad. Optom.

(1937)

GarnerL. et al.

The effects of phenylephrine hydrochloride on the resting focus of accommodation

Invest. Ophthal. visual Sci.

(1983)

HoganR.E. et al.

The effects of moderate doses of ethanol on heterophoria and other aspects of binocular vision

Ophthal. Physiol. Opt.

(1983)

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Citation Excerpt :
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Dynamic interactions between accommodation and convergence are velocity sensitive

Abstract

Am. J. Ophthal.

Am. J. Surg.

Vision Res.

Vision Res.

Vision Res.

Vision Res.

Vision Res.

Vision Res.

Time-course and variability of dark focus

Invest. Ophthal. visual Sci.

Factors influencing accommodation responses of the human eye

J. opt. Soc. Am.

Ocular-focus stimulator

J. opt. Soc. Am.

Accommodative hysteresis: a precursor for induced myopia

Invest. Ophthal. visual Sci.

The accommodation reflex and its stimulus

Br. J. Ophthal.

The reciprocal actions of accommodation and convergence

J. Physiol. Lond.

On the relationship between accommodation and accommodative convergence. I Linearity

Am. J. Optom. Physiol. Opt.

A experimental analysis of the accommodation-covergence relations

Am. J. Optom. Arch. Am. Acad. Optom.

The effects of phenylephrine hydrochloride on the resting focus of accommodation

Invest. Ophthal. visual Sci.

The effects of moderate doses of ethanol on heterophoria and other aspects of binocular vision

Ophthal. Physiol. Opt.