Aging and dark adaptation

Older adults have serious difficulty seeing under low illumination and at night, even in the absence of ocular disease. Optical changes in the aged eye, such as pupillary miosis and increased lens density, cannot account for the severity of this problem, and little is known about its neural basis. D...

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Bibliographic Details
Published in:Vision research (Oxford) 1999-11, Vol.39 (23), p.3975-3982
Main Authors: Jackson, Gregory R., Owsley, Cynthia, McGwin, Gerald
Format: Article
Language:English
Subjects:
Adult
Aged
Aged, 80 and over
Ageing
Aging - physiology
Biological and medical sciences
Dark adaptation
Dark Adaptation - physiology
Development. Senescence. Regeneration. Transplantation
Fundamental and applied biological sciences. Psychology
Human
Humans
Middle Aged
Retinal Rod Photoreceptor Cells - physiology
Rhodopsin
Rods
Scotopic sensitivity
Vertebrates: nervous system and sense organs
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Summary:Older adults have serious difficulty seeing under low illumination and at night, even in the absence of ocular disease. Optical changes in the aged eye, such as pupillary miosis and increased lens density, cannot account for the severity of this problem, and little is known about its neural basis. Dark adaptation functions were measured on 94 adults ranging in age from the 20s to the 80s to assess the rate of rod-mediated sensitivity recovery after exposure to a 98% bleach. Fundus photography and a grading scale were used to characterize macular health in subjects over age 49 in order to control for macular disease. Thresholds for each subject were corrected for lens density based on individual estimates, and pupil diameter was controlled. Results indicated that during human aging there is a dramatic slowing in rod-mediated dark adaptation that can be attributed to delayed rhodopsin regeneration. During the second component of the rod-mediated phase of dark adaptation, the rate of sensitivity recovery decreased 0.02 log unit/min per decade, and the time constant of rhodopsin regeneration increased 8.4 s/decade. The amount of time to reach within 0.3 log units of baseline scotopic sensitivity increased 2.76 min/decade. These aging-related changes in rod-mediated dark adaptation may contribute to night vision problems commonly experienced by the elderly.
ISSN:0042-6989
1878-5646
DOI:10.1016/S0042-6989(99)00092-9