Discomfort from glare: The role of pupillary hippus

Howarth, Peter A.; Heron, Gordon; Greenhouse, Daniel; Bailey, IL; Berman, S.M.

doi:10.1177/096032719302500106

Cited by 39 publications

(22 citation statements)

References 2 publications

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“…46 Indeed, it has been demonstrated that an intact trigeminal nerve is necessary to experience visual discomfort. 47 More recently, however, Howarth et al 48 showed that hippus (an irregular oscillation of iris constriction and dilation under intense illumination) is not consistently associated with subjective reports of visual discomfort. However, they assessed the relationship between hippus and visual discomfort in only one subject.…”

Section: Discussionmentioning

confidence: 99%

Macular Pigment and Visual Performance in Glare: Benefits for Photostress Recovery, Disability Glare, and Visual Discomfort

Stringham¹,

Garcia²,

Smith³

et al. 2011

Invest. Ophthalmol. Vis. Sci.

108

123

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MP correlates with three aspects of visual performance in glare. Unlike previous studies of MP and glare, the present study used free-viewing conditions, in which effects of iris pigmentation and pupil size could be accounted for. The effects described, therefore, can be extended more confidently to real-world, practical visual performance benefits. Greater iris constriction resulted (paradoxically) in greater visual discomfort. This finding may be attributable to the neurobiologic mechanism that mediates the pain elicited by light.

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Section: Discussionmentioning

confidence: 99%

Macular Pigment and Visual Performance in Glare: Benefits for Photostress Recovery, Disability Glare, and Visual Discomfort

Stringham¹,

Garcia²,

Smith³

et al. 2011

Invest. Ophthalmol. Vis. Sci.

108

123

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“…inflammation of the eyes and lids); dry or watery eyes; itchiness; tense muscles; breakdown of vision, blurred or double vision; headaches or fatigue. Such symptoms can further lead to discomfort and stress [7]. Discomfort glare in interior lighting is quantified by the Unified Glare Rating (UGR), with maximum UGR limits given by standards for various applications that typically range from 13 to 28.…”

Section: Glare From Led Lightingmentioning

confidence: 99%

A summary of LED lighting impacts on health

Ticleanu¹,

Littlefair²

2015

ijsl

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Lighting can affect the health of people in buildings. This goes beyond the safety aspects of providing enough illumination to see by; lighting affects mood and human circadian rhythms, while poor lighting can cause glare, headaches, eyestrain, aches and pains associated with poor body posture or, in extreme cases, skin conditions and various types of sight loss. These aspects ought to be considered by designers and building owners and occupiers in order to improve the lit environment and use adequate lighting and lighting controls that meet the recommendations of codes and standards. Various types of lighting can have different impacts depending on their spectral, optical and electrical characteristics. This paper discusses potential impacts of LED lighting on human health, and is based on a recent BRE review of research investigating the most typical effects of lighting on human health.

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“…The few studies that have considered physiological correlates of discomfort have focused mainly on its efferent manifestations. Early work, for example, was concerned with pupil size fluctuations (Fugate and Fry, 1956), particularly pupillary hippus (an involuntary spasm of the pupil) (Fry and King, 1975;Hopkinson, 1956) but later work showed little correlation with pupil size fluctuations and discomfort glare (Howarth et al, 1993). Electromyographic techniques (EMG) have also been employed, which examined facial muscle activity under conditions of discomfort (Berman et al, 1994;Murray et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Cortical hyperexcitability and sensitivity to discomfort glare

et al. 2015

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It is well established that there are two main aspects to glare, the visual impairment and the discomfort, known as disability and discomfort glare, respectively. In contrast to the case of disability glare we understand very little about the underlying mechanisms or physiology of discomfort glare. This study attempts to elucidate the neural mechanisms involved using fMRI and glare sources with controlled levels of retinal illuminance. Prior to carrying out the fMRI experiment, we determined each participant's discomfort glare threshold. The participants were then divided into two groups of equal size based on their ranked sensitivity to discomfort glare, a low and high sensitivity group. In the fMRI experiment each participant was presented with three levels of glare intensity whilst simultaneously required to carry out a simple behavioral task. We compared BOLD responses between the two groups and found that the group more sensitive to glare had an increased response that was localized at three discrete, bilateral cortical locations: one in the cunei, one in the lingual gyri and one in the superior parietal lobules. This increased response was present for all light levels tested, whether or not they were intense enough to cause discomfort glare. Based on the results, we present the case that discomfort glare may be a response to hyperexcitability or saturation of visual neurons.

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Discomfort from glare: The role of pupillary hippus

Cited by 39 publications

References 2 publications

Macular Pigment and Visual Performance in Glare: Benefits for Photostress Recovery, Disability Glare, and Visual Discomfort

Macular Pigment and Visual Performance in Glare: Benefits for Photostress Recovery, Disability Glare, and Visual Discomfort

A summary of LED lighting impacts on health

Cortical hyperexcitability and sensitivity to discomfort glare

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