Variation in the pupil light reflex between winter and summer seasons

Münch, Mirjam; Kourti, Persefoni; Brοuzas, Dimitrios; Kawasaki, Aki

doi:10.1111/aos.12966

Cited by 15 publications

(17 citation statements)

References 8 publications

(3 reference statements)

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“…LeGates and colleagues have provided compelling evidence for the induction of depression-like symptoms in mice by shortening the photoperiod (7 h light/dark cycle) mediated through ipRGCs (LeGates et al, 2012). In healthy humans, the pupillary light reflex has also shown varying responsiveness in relation to changes in seasonal light (Münch et al, 2016). …”

Section: Introductionmentioning

confidence: 99%

Pupillary response abnormalities in depressive disorders

Laurenzo¹,

Kardon

Ledolter

et al. 2016

Psychiatry Research

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Depressive disorders lack objective physiological measurements to characterize the affected population and facilitate study of relevant mechanisms. The melanopsin-mediated light signaling pathway may contribute to seasonal variation and can be measured non-invasively by pupillometry. We prospectively studied changes in melanopsin-mediated pupillary constriction in 19 participants with major depressive disorder (MDD) and 10 control across the summer and winter solstices. The melanopsin-mediated response, as measured by the pupil's sustained constriction six s after a high intensity blue light stimulus, was marginally attenuated in those with MDD relative to controls (p=0.071). The participants with MDD unexpectedly showed a significantly reduced transient pupillary response to low intensity red (p=0.011) and blue light (p=0.013), but not high intensity red and blue light. Sustained pupillary constriction in response to high intensity blue light was more pronounced with increasing daylight hours (p=0.037) and was more strongly related to objectively measured versus estimated light exposure. Melanopsin-mediated impairments in pupil response may serve as a biological marker for vulnerability to depression in low light conditions. Assessment of these and other responses to light stimuli, such as response to low intensity light, may be useful for the study of the neurobiology of MDD and related mood disorders.

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Section: Introductionmentioning

confidence: 99%

Pupillary response abnormalities in depressive disorders

Laurenzo¹,

Kardon

Ledolter

et al. 2016

Psychiatry Research

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“…We, therefore, examined the within-subject between-day test-retest reliability of an alternative protocol without mydriatics with increased light intensity and compared this to the previously found very high reliability of the protocol with mydriatics [ 16 ]. In a previous different protocol to assess PIPR, outcome measures showed variability across seasons [ 34 ]. We, therefore, evaluated whether our protocol without mydriatics might result in a more stable trait-like biomarker, robust across seasons, by assessing the test-retest reliability across the winter and summer.…”

Section: Introductionmentioning

confidence: 99%

Individual Differences in the Post-Illumination Pupil Response to Blue Light: Assessment without Mydriatics

Bruijel

Meijden

Bijlenga

et al. 2016

Biology

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Melanopsin-containing retinal ganglion cells play an important role in the non-image forming effects of light, through their direct projections on brain circuits involved in circadian rhythms, mood and alertness. Individual differences in the functionality of the melanopsin-signaling circuitry can be reliably quantified using the maximum post-illumination pupil response (PIPR) after blue light. Previous protocols for acquiring PIPR relied on the use of mydriatics to dilate the light-exposed eye. However, pharmacological pupil dilation is uncomfortable for the participants and requires ophthalmological expertise. Hence, we here investigated whether an individual’s maximum PIPR can be validly obtained in a protocol that does not use mydriatics but rather increases the intensity of the light stimulus. In 18 participants (5 males, mean age ± SD: 34.6 ± 13.6 years) we evaluated the PIPR after exposure to intensified blue light (550 µW/cm2) provided to an undilated dynamic pupil. The test-retest reliability of the primary PIPR outcome parameter was very high, both between day-to-day assessments (Intraclass Correlation Coefficient (ICC) = 0.85), as well as between winter and summer assessments (ICC = 0.83). Compared to the PIPR obtained with the use of mydriatics and 160 µW/cm2 blue light exposure, the method with intensified light without mydriatics showed almost zero bias according to Bland-Altman plots and had moderate to strong reliability (ICC = 0.67). In conclusion, for PIPR assessments, increasing the light intensity is a feasible and reliable alternative to pupil dilation to relieve the participant’s burden and to allow for performance outside the ophthalmological clinic.

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“…The difference in the PIPR between the studies may also have occurred due to the seasonal variation of the PIPR (Münch et al, 2016) in the recent study (Laurenzo et al, 2016) that was conducted in both winter and summer months as opposed to the previous SAD study (Roecklein et al, 2013), which was conducted in winter when the depressive episodes of the patients with SAD were at peak. The Laurenzo et al (2016) study further quantified the peak constriction amplitude and transient PLR in response to low intensity red and blue light stimuli (~ 11.9 log quanta.cm -2 .s -1 ) and observed a significant reduction in the peak constriction and transient PLR amplitudes in MDD (Laurenzo et al, 2016).…”

Section: Figurementioning

confidence: 95%

“…A recent study, however, observed no difference in the PIPR in patients with MDD including SAD compared to healthy individuals (Laurenzo et al, 2016). The discrepancy in the PIPR results among the patients with depression between the two studies may have occurred due to the PIPR measurements in the (Laurenzo et al, 2016) study being conducted during both the winter and summer months when depression and remission occur respectively, possibly altering the melanopsin function with season (Münch, Kourti, Brouzas, & Kawasaki, 2016).…”

Section: Chapter 1: Introductionmentioning

confidence: 91%

“…Laurenzo et al (2016) hemisphere where temperatures range between 32°C to -28°C with participants' individual light exposure levels on average, ranging from 2,255 lux in summer to 207 lux in winter (Laurenzo et al, 2016). Since, seasonal changes in light exposure have been shown to affect the PIPR in normal individuals (Münch et al, 2016), lower PIPR associated with lower light exposure is therefore expected in MDD patients (Laurenzo et al, 2016). The current study was conducted in Brisbane, Australia, a city in the southern hemisphere, with a sub-tropical climate and the study measured similar light exposure levels in the summer and winter months.…”

Section: Contrast Sensitivity (Cs)mentioning

confidence: 99%

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An Evaluation of Melanopsin Function and Light Exposure in Depressive Disorders

Ojha¹

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Aberrant light exposure causes depression in animals through a pathway involving the recently discovered intrinsically photosensitive Retinal Ganglion Cells (ipRGCs). The photopigment melanopsin expressed in ipRGCs encodes irradiance to signal to the nonimage-forming centres of the brain, including the suprachiasmatic nucleus (SCN) for circadian photoentrainment and the olivary pretectal nucleus (OPN) to control the pupil light reflex. Mouse models have further identified ipRGC projections to the brain nuclei that regulate mood and behaviour. In humans, the post-illumination pupil response (PIPR), a sustained pupillary constriction after light offset, is used as a direct and non-invasive biomarker of ipRGC function.The PIPR amplitude is reduced in humans with seasonal affective disorder (SAD) that shows a seasonal variation in depressive episodes with a peak manifestation in winter when the solar light exposure is low, but a recent study including patients with non-seasonal depressive disorder did not detect ipRGC dysfunction. Moreover, neither study measured the ambient light exposure levels in patients with depression for comparison to healthy individuals without depression. The knowledge of the role of light coding cells (ipRGCs) in major depressive disorder (MDD) is incomplete unless the relationship between ambient light exposure levels and melanopsin function is evaluated. This study aims to measure the environmental light exposure levels and their relationship with melanopsin-mediated PIPR in non-seasonal depression. It is hypothesised that the patients with non-seasonal depression are exposed to low light levels and this is associated with impaired melanopsin function.A sample of 22 adults was recruited, including people with non-seasonal depression (n = 8, median age: 35 years) and healthy age-matched controls (n = 14, median age: 29 years).The presence of a DSM-IV MDD was assessed using the Mini International Neuropsychiatry ii Interview (MINI 6). The severity of depression symptoms was assessed with the Beck Depression Inventory (BDI-II). Individuals with recurrent MDD assessed with the MINI and a positive screen on the Seasonal Pattern Assessment Questionnaire and the Hamilton Depression Rating Scale-SAD (HDRS-SAD) were excluded as SAD. Both groups had visual acuity ≥ 6/6, normal colour vision and intraocular pressure (IOP) ≤ 21 mmHg, no corneal and lenticular opacities and normal retinae and optic discs. The ipRGC-mediated PIPR was measured using a short duration (1 s) high irradiance (15.5 log quanta.cm -2 .s -1 ) short wavelength (blue appearing) light stimulus with a custom built Maxwellian view pupillometer. Light exposure levels, sleep-wake times and sleep efficiency were determined over 2 weeks with an ambulatory light sensor device (Geneactive).The mean daily light exposure levels were similar between the groups and there were no statistically significant differences between the groups for light exposure levels as a function of clock hours, nor in the total number of minutes of exposu...

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Variation in the pupil light reflex between winter and summer seasons

Cited by 15 publications

References 8 publications

Pupillary response abnormalities in depressive disorders

Pupillary response abnormalities in depressive disorders

Individual Differences in the Post-Illumination Pupil Response to Blue Light: Assessment without Mydriatics

An Evaluation of Melanopsin Function and Light Exposure in Depressive Disorders

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