Eyeing up the Future of the Pupillary Light Reflex in Neurodiagnostics

Diagnostics, Год журнала: 2018, Номер 8(1), С. 19 - 19

Опубликована: Март 13, 2018

The pupillary light reflex (PLR) describes the constriction and subsequent dilation of pupil in response to as a result antagonistic actions iris sphincter dilator muscles. Since these muscles are innervated by parasympathetic sympathetic nervous systems, respectively, different parameters PLR can be used indicators for either or modulation. Thus, provides an important metric autonomic system function that has been exploited wide range clinical applications. Measurement using dynamic pupillometry is now established quantitative, non-invasive tool assessment traumatic head injuries. This review examines more recent application diagnostic conditions, varying from neurodegenerative disease exposure toxic chemicals, well its potential diagnosis infectious disease.

Язык: Английский

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Standards in Pupillography

Frontiers in Neurology, Год журнала: 2019, Номер 10

Опубликована: Фев. 21, 2019

The number of research groups studying the pupil is increasing, as publications. Consequently, new standards in pupillography are needed to formalize methodology including recording conditions, stimulus characteristics, well suitable parameters evaluation. Since description intrinsically photosensitive retinal ganglion cells (ipRGCs) there has been an increased interest and broader application ophthalmology other fields psychology chronobiology. Colour plays important role not only but also clinical observational therapy studies like gene hereditary degenerations psychopathology. Stimuli can vary size, brightness, duration, wavelength. Stimulus paradigms determine whether rhodopsin-driven rod responses, opsin-driven cone or melanopsin-driven ipRGC responses primarily elicited. Background illumination, adaptation state, instruction for participants will furthermore influence results. This standard recommends a minimum set variables be used specified publication methodologies. Initiated at 32nd International Pupil Colloquium 2017 Morges, Switzerland, aim this manuscript outline based on current knowledge experience experts order achieve greater comparability pupillographic studies. Such particularly facilitate proper by researchers field. First we describe general standards, followed specific suggestions concerning demands different targets research: afferent efferent reflex arc, pharmacology, psychology, sleepiness-related animal

Язык: Английский

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Melanopsin photoreception contributes to human visual detection, temporal and colour processing

Scientific Reports, Год журнала: 2018, Номер 8(1)

Опубликована: Фев. 23, 2018

Abstract The visual consequences of melanopsin photoreception in humans are not well understood. Here we studied using a technique photoreceptor silent substitution with five calibrated spectral lights after minimising the effects individual differences optical pre-receptoral filtering and desensitising penumbral cones shadow retinal blood vessels. We demonstrate that putative melanopsin-mediated image-forming vision corresponds to an opponent S-OFF L + M-ON response property, average temporal resolution up approximately 5 Hz, >10x higher thresholds than red-green colour vision. With capacity for signalling integrating slowly changing lights, melanopsin-expressing intrinsically photosensitive ganglion cells maybe fifth type peripheral

Язык: Английский

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Quadrant Field Pupillometry Detects Melanopsin Dysfunction in Glaucoma Suspects and Early Glaucoma

Scientific Reports, Год журнала: 2016, Номер 6(1)

Опубликована: Сен. 13, 2016

Abstract It is difficult to detect visual function deficits in patients at risk for glaucoma (glaucoma suspects) and early disease stages with conventional ophthalmic tests such as perimetry. To this end, we introduce a novel quadrant field measure of the melanopsin retinal ganglion cell mediated pupil light response corresponding typical glaucomatous arcuate defects. The melanopsin-mediated post-illumination (PIPR) was measured 46 different including suspects compared healthy group 21 participants no disease. We demonstrate that superonasal PIPR differentiated from controls fair (AUC = 0.74) excellent 0.94) diagnostic accuracy, respectively. provides linear functional correlate structural nerve fibre thinning patients. This first report stimulation detects dysfunction pre-perimetric may have future implications treatment decisions suspects.

Язык: Английский

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Melanopsin-mediated pupil function is impaired in Parkinson’s disease

Scientific Reports, Год журнала: 2018, Номер 8(1)

Опубликована: Май 11, 2018

Abstract Parkinson’s disease (PD) is characterised by non-motor symptoms including sleep and circadian disruption. Melanopsin-expressing intrinsically photosensitive Retinal Ganglion Cells (ipRGC) transmit light signals to brain areas controlling rhythms the pupil reflex. To determine if observed in PD are linked ipRGC dysfunction, we evaluated melanopsin rod/cone contributions response medicated participants with ( n = 17) controls 12). Autonomic tone was measuring pupillary unrest darkness. In group, there evidence for an attenuated post-illumination (PIPR) amplitude reduced constriction amplitude, PIPR amplitudes did not correlate measures of quality, retinal nerve fibre layer thickness, severity, or medication dosage. Both groups exhibited similar unrest. We show that melanopsin- rod/cone-photoreceptor control pathway impaired people early-stage who have no clinically observable ophthalmic abnormalities. Given ipRGCs project targets involved arousal, rhythms, dysfunction may underpin some PD.

Язык: Английский

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Crosstalk: The diversity of melanopsin ganglion cell types has begun to challenge the canonical divide between image‐forming and non‐image‐forming vision

The Journal of Comparative Neurology, Год журнала: 2020, Номер 528(12), С. 2044 - 2067

Опубликована: Янв. 31, 2020

Melanopsin ganglion cells have defied convention since their discovery almost 20 years ago. In the following, many types of these intrinsically photosensitive retinal (ipRGCs) emerged. mouse retina, there are currently six known (M1-M6) melanopsin cells, each with unique morphology, mosaics, connections, physiology, projections, and functions. While melanopsin-expressing usually associated behaviors like circadian photoentrainment pupillary light reflex, characterization multiple has demonstrated a reach that may extend far beyond non-image-forming vision. fact, studies shown individual potential to impact image-forming functions contrast sensitivity color opponency. Thus, goal this review is summarize morphological functional aspects in retina highlight respective roles Although cell do project brain targets, it important note only first step determining influence on Even so, visual system canonically been divided into two realms begun challenge boundary between them, providing an overlap information complementary rather than redundant. Further photoreceptors will no doubt continue illustrate ever-expanding role for

Язык: Английский

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Photoreceptor contributions to the human pupil light reflex

Journal of Photochemistry and Photobiology, Год журнала: 2023, Номер 15, С. 100178 - 100178

Опубликована: Апрель 2, 2023

The pupil reacts to the amount of light reaching eye. It reduces its size when is high and dilates at low levels allow entrance more photons. This behavior called reflex (PLR). Recent investigations in humans were conducted understand how photoreceptor signals are combined drive reflex. review about physiological processes that govern humans. In particular, cone-opsins, rhodopsin, melanopsin photoreception contribute governing PLR. We also summarize on assessment PLR clinical settings.

Язык: Английский

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Pupillary responses in non-proliferative diabetic retinopathy

Scientific Reports, Год журнала: 2017, Номер 7(1)

Опубликована: Март 23, 2017

Abstract The goal of this study was to determine the extent rod-, cone-, and melanopsin-mediated pupillary light reflex (PLR) abnormalities in diabetic patients who have non-proliferative retinopathy (NPDR). Fifty subjects different stages NPDR 25 age-equivalent, non-diabetic controls participated. PLRs were measured response full-field, brief-flash stimuli under conditions that target rod, cone, intrinsically-photosensitive (melanopsin) retinal ganglion cell pathways. Pupil responses compared among groups using age-corrected linear mixed models. Compared control, mean baseline pupil diameters significantly smaller for all patient dark (all p < 0.001) moderate-severe group (p = 0.003). Pairwise comparisons indicated: (1) PLR reduced mild (both 0.001); (2) cone-mediated 0.008); (3) no significant differences rod-mediated responses. data indicate separately assess function driven by photoreceptor classes. results provide evidence compromised neural these a promising approach quantifying their abnormalities.

Язык: Английский

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Intrinsically Photosensitive Retinal Ganglion Cell Function, Sleep Efficiency and Depression in Advanced Age-Related Macular Degeneration

Investigative Ophthalmology & Visual Science, Год журнала: 2017, Номер 58(2), С. 990 - 990

Опубликована: Фев. 9, 2017

Purpose: Melanopsin expressing intrinsically photosensitive retinal ganglion cells (ipRGC) input to multiple brain regions including those for pupil control, circadian rhythms, sleep and mood regulation. Here we measured ipRGC function its relationship quality depression in patients with advanced AMD. Methods: The melanopsin-mediated post-illumination response (PIPR) was 53 AMD (age 78.8 ± 8.8 years) 20 healthy controls 72.5 3.3 years). Sleep efficiency assessed using the Pittsburgh Quality Index (PSQI). Risk of determined Center Epidemiologic Studies Depression questionnaire. Results: group showed significantly reduced constrictions (P = 0.039); PIPR amplitudes 0.003); global scores 0.01); higher levels < 0.001) than control group. There a significant correlation between amplitude score 0.01). correlated 0.008; regression, P 0.01, R2 0.13), but not 0.23) no scores. Conclusions: Intrinsically RGC dysfunction contributes observed reduction efficiency. may indicate photic suprachiasmatic nucleus ventrolateral preoptic area due

Язык: Английский

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Melanopsin and Cone Photoreceptor Inputs to the Afferent Pupil Light Response

Frontiers in Neurology, Год журнала: 2019, Номер 10

Опубликована: Май 22, 2019

Background: Retinal photoreceptors provide the main stage in mammalian eye for regulating retinal illumination through changes pupil diameter, with a small population of melanopsin-expressing intrinsically photosensitive ganglion cells (ipRGCs) forming primary afferent pathway this response. The purpose study is to determine how melanopsin interacts three cone photoreceptor classes human modulate light-adapted Methods: We investigated independent and combined contributions inner outer inputs participants trichromatic colour vision using method independently control excitations ipRGCs, cones rods retina. Results: show that melanopsin-directed stimuli cause transient constriction generated by shadow blood vessels; desensitising these penumbral signals uncovers signature response includes longer latency slower velocity than cone-directed stimuli, which remains sustained post-stimulus offset. Compared melanopsin-mediated responses, photoreceptor-initiated responses are more faster latencies, higher velocities secondary at light reveal additive signals. Conclusions: visual system uses L-, M, S-cone accomplish tonic modulations size image contrast. ipRGCs mediate longer-term, set diameter during extended exposures.

Язык: Английский

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