Document Detail

Does Pupil Constriction under Blue and Green Monochromatic Light Exposure Change with Age?
MedLine Citation:
PMID:  22653894     Owner:  NLM     Status:  In-Data-Review    
Many nonvisual functions are regulated by light through a photoreceptive system involving melanopsin-expressing retinal ganglion cells that are maximally sensitive to blue light. Several studies have suggested that the ability of light to modulate circadian entrainment and to induce acute effects on melatonin secretion, subjective alertness, and gene expression decreases during aging, particularly for blue light. This could contribute to the documented changes in sleep and circadian regulatory processes with aging. However, age-related modification in the impact of light on steady-state pupil constriction, which regulates the amount of light reaching the retina, is not demonstrated. We measured pupil size in 16 young (22.8 ± 4 years) and 14 older (61 ± 4.4 years) healthy subjects during 45-second exposures to blue (480 nm) and green (550 nm) monochromatic lights at low (7 × 10(12) photons/cm(2)/s), medium (3 × 10(13) photons/cm(2)/s), and high (10(14) photons/cm(2)/s) irradiance levels. Results showed that young subjects had consistently larger pupils than older subjects for dark adaptation and during all light exposures. Steady-state pupil constriction was greater under blue than green light exposure in both age groups and increased with increasing irradiance. Surprisingly, when expressed in relation to baseline pupil size, no significant age-related differences were observed in pupil constriction. The observed reduction in pupil size in older individuals, both in darkness and during light exposure, may reduce retinal illumination and consequently affect nonvisual responses to light. The absence of a significant difference between age groups for relative steady-state pupil constriction suggests that other factors such as tonic, sympathetic control of pupil dilation, rather than light sensitivity per se, account for the observed age difference in pupil size regulation. Compared to other nonvisual functions, the light sensitivity of steady-state pupil constriction appears to remain relatively intact and is not profoundly altered by age.
Véronique Daneault; Gilles Vandewalle; Marc Hébert; Petteri Teikari; Ludovic S Mure; Julien Doyon; Claude Gronfier; Howard M Cooper; Marie Dumont; Julie Carrier
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of biological rhythms     Volume:  27     ISSN:  1552-4531     ISO Abbreviation:  J. Biol. Rhythms     Publication Date:  2012 Jun 
Date Detail:
Created Date:  2012-06-01     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8700115     Medline TA:  J Biol Rhythms     Country:  United States    
Other Details:
Languages:  eng     Pagination:  257-64     Citation Subset:  IM    
*Functional Neuroimaging Unit, University of Montreal Geriatric Institute, Qc, Canada.
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