Instrument Review: The Sheedy Fixation Disparometer

Dwyer, Peter

doi:10.1111/j.1444-0938.1982.tb03677.x

Cited by 3 publications

(2 citation statements)

References 2 publications

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“…Horizontal fixation disparity was only measured in the second test period ( n = 20). Immediately after completing the 10-min computer-work period, the participants turned their chair around, put on a pair of polarized glasses, and placed their head in a chin-and-head support facing a Sheedy fixation disparometer (Dwyer 1982 ). The test distance was approximately the same as during the computer-work periods, 60 cm.…”

Section: Methodsmentioning

confidence: 99%

Visual and psychological stress during computer work in healthy, young females—physiological responses

Mork

Falkenberg

Fostervold

et al. 2018

Int Arch Occup Environ Health

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PurposeAmong computer workers, visual complaints, and neck pain are highly prevalent. This study explores how occupational simulated stressors during computer work, like glare and psychosocial stress, affect physiological responses in young females with normal vision.MethodsThe study was a within-subject laboratory experiment with a counterbalanced, repeated design. Forty-three females performed four 10-min computer-work sessions with different stress exposures: (1) minimal stress; (2) visual stress (direct glare); (3) psychological stress; and (4) combined visual and psychological stress. Muscle activity and muscle blood flow in trapezius, muscle blood flow in orbicularis oculi, heart rate, blood pressure, blink rate and postural angles were continuously recorded. Immediately after each computer-work session, fixation disparity was measured and a questionnaire regarding perceived workstation lighting and stress was completed.ResultsExposure to direct glare resulted in increased trapezius muscle blood flow, increased blink rate, and forward bending of the head. Psychological stress induced a transient increase in trapezius muscle activity and a more forward-bent posture. Bending forward towards the computer screen was correlated with higher productivity (reading speed), indicating a concentration or stress response. Forward bent posture was also associated with changes in fixation disparity. Furthermore, during computer work per se, trapezius muscle activity and blood flow, orbicularis oculi muscle blood flow, and heart rate were increased compared to rest.ConclusionsExposure to glare and psychological stress during computer work were shown to influence the trapezius muscle, posture, and blink rate in young, healthy females with normal binocular vision, but in different ways. Accordingly, both visual and psychological factors must be taken into account when optimizing computer workstations to reduce physiological responses that may cause excessive eyestrain and musculoskeletal load.

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Section: Methodsmentioning

confidence: 99%

Visual and psychological stress during computer work in healthy, young females—physiological responses

Mork

Falkenberg

Fostervold

et al. 2018

Int Arch Occup Environ Health

View full text Add to dashboard Cite

show abstract

“…More recently, a clinical instrument called the Disparometer, which is capable of measuring actual fixation disparities has been introduced by Sheedy and Saladin (1975). This instrument has been reviewed in detail by Dwyer (1982) and Daum (1983). Sheedy (1980b) outlines some of the suggested procedures for use of the Disparometer.…”

Section: Introductionmentioning

confidence: 99%

The effect of illumination and foveal fusion lock on clinical fixation disparity measurements with the Sheedy disparometer

Wildsoet¹

1985

Ophthalmic and Physiological Optics

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The Sheedy Disparometer is a clinical instrument designed to measure fixation disparity and hence determine forced vergence--fixation disparity curves. The target design includes a central 1.5 degrees fusion-free area. The effect of introducing a central fixation target to the instrument is investigated along with the influence of ambient illumination level on fixation disparity. All curve parameters, i.e. curve type, slope, X- and Y-intercepts were found to significantly alter with the introduction of a foveal lock. Illumination changes did not cause significant differences in any parameter.

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The Effect of Illumination and Foveal Fusion Lock on Clinical Fixation Disparity Measurements With the Sheedy Disparometer

Wildsoet¹,

Cameron²

1985

Ophthalmic Physiologic Optic

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Instrument Review: The Sheedy Fixation Disparometer

Abstract: This paper describes the construction and operation of the Sheedy fixation disparometer and the methods suggested for the analysis of fixation disparity determined by its use.

Cited by 3 publications

References 2 publications

Visual and psychological stress during computer work in healthy, young females—physiological responses

Visual and psychological stress during computer work in healthy, young females—physiological responses

The effect of illumination and foveal fusion lock on clinical fixation disparity measurements with the Sheedy disparometer

The Effect of Illumination and Foveal Fusion Lock on Clinical Fixation Disparity Measurements With the Sheedy Disparometer

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