Variation of Accommodation in Vertical Directions of Gaze*

Ripple, Paul H.

doi:10.1016/0002-9394(52)91453-0

Cited by 53 publications

(26 citation statements)

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“…Extraretinal signals from neck proprioception influence not only static eye position but also the dynamics of the monocularly driven accommodative vergence eye movement (Han & Lennerstrand, 1998). The interaction between the muscles of the neck and the extraocular muscles of the eye has also been demonstrated electromyographically (Valentino & Fabozzo, 1993; see also Ripple, 1952;Atchison et al, 1994;Mon-Williams et al, 1999). The subjects could have suppressed the individual state of their physiological arousal in order to assist the production of negative accommodation ⁄ vergence.…”

Section: Precentral and Postcentral Gyrus Rcbf Decreases During Nvamentioning

confidence: 97%

Neuroanatomical correlates of voluntary inhibition of accommodation/vergence under monocular open‐loop viewing conditions

Richter

Andersson

Schneider

et al. 2005

Eur J of Neuroscience

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The purpose of this work is to identify human neural circuits involved in inhibition of accommodation/vergence by contrasting the cortical functions subservient to negative voluntary accommodation/vergence (NVA) with those evoked by active fixation in darkness (FIX). Five subjects with normal corrected acuity were studied using positron emission tomography and the HO bolus technique. The dominant right eye viewed a laser speckle pattern (633 nm) whose direction and velocity of motion were determined by the refractive state of the eye. The speckle pattern was presented at a distance of 1.8 m (0.55 D). The non-dominant eye was patched. Subjects performed two tasks counterbalanced for order effects: (i) attempted fixation on the remembered target in darkness with the dominant eye open and 'fixating'; and (ii) voluntary reduction of the laser speckle flow during each alternate 20-s epoch when a convex +2.0 D lens was placed in front of the right eye causing the speckle pattern to move downwards at 3 degrees /s. Comparison of the condition of NVA with the condition of FIX indicated widespread occipital activation. Decreases in absolute regional cerebral blood flow occurred in the superior parietal cortex (BA 5), frontal cortex (BA 8 and 10) and within the postcentral/precentral gyrus (BA 1/2/3/4) bilaterally where deactivation clusters eclipsed the presumed neck and shoulder areas. Negative accommodation/vergence appears to be driven by a reduction of parasympathetic tone, and has the effect of shutting down brain regions known to be involved in regulating visual search as well as a centrally controlled eye-head-neck-shoulder motor programme responsible for posturing gaze.

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Section: Precentral and Postcentral Gyrus Rcbf Decreases During Nvamentioning

confidence: 97%

Neuroanatomical correlates of voluntary inhibition of accommodation/vergence under monocular open‐loop viewing conditions

Richter

Andersson

Schneider

et al. 2005

Eur J of Neuroscience

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“…It should also be noted that laptop computers are more typically used in downward gaze while smartphone type devices can be held in primary or downward gaze. Variations in the angle of gaze may also alter either the accommodative and/or vergence response, 81–83 and therefore the level of symptoms experienced. Age and gender. The prevalence of dry eye increases with age and is higher in women than men 13,84–90 .…”

Section: Cvs and Dry Eyementioning

confidence: 99%

Computer vision syndrome: a review of ocular causes and potential treatments

Rosenfield

2011

Ophthalmic Physiologic Optic

517

405

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Computer vision syndrome (CVS) is the combination of eye and vision problems associated with the use of computers. In modern western society the use of computers for both vocational and avocational activities is almost universal. However, CVS may have a significant impact not only on visual comfort but also occupational productivity since between 64% and 90% of computer users experience visual symptoms which may include eyestrain, headaches, ocular discomfort, dry eye, diplopia and blurred vision either at near or when looking into the distance after prolonged computer use. This paper reviews the principal ocular causes for this condition, namely oculomotor anomalies and dry eye. Accommodation and vergence responses to electronic screens appear to be similar to those found when viewing printed materials, whereas the prevalence of dry eye symptoms is greater during computer operation. The latter is probably due to a decrease in blink rate and blink amplitude, as well as increased corneal exposure resulting from the monitor frequently being positioned in primary gaze. However, the efficacy of proposed treatments to reduce symptoms of CVS is unproven. A better understanding of the physiology underlying CVS is critical to allow more accurate diagnosis and treatment. This will enable practitioners to optimize visual comfort and efficiency during computer operation.

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“…That reduces stress on the extraocular muscles. The ability to accommodate improves (Ripple, 1952), and reports of headaches (Tyrrell and Leibowitz, 1990), eye strain (Tyrrell and Leibowitz, 1990), and fatigue decrease (Owens and Wolf-Kelly, 1987). Because less of the cornea is exposed to the atmosphere, the risk of dry eye syndrome is reduced (Tsubota and Nakamori, 1993).…”

Section: Posture and Vision Interactmentioning

confidence: 99%