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Juan A. Sepulveda, Andrew J. Anderson, Joanne M. Wood, Allison M. McKendrick; Central and peripheral motion perception under mesopic conditions in older adults. Journal of Vision 2020;20(11):876. doi: https://doi.org/10.1167/jov.20.11.876.
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© ARVO (1962-2015); The Authors (2016-present)
This study aimed to determine how healthy ageing affects motion perception under mesopic relative to photopic light levels in both central and peripheral vision.
We compared the performance of 18 younger (20-31 years, mean: 25 years) and 18 older (60-79 years, mean: 70 years) visually normal adults on four motion tasks administered in a random order: grating contrast required to discriminate motion direction, translational global motion coherence, surround suppression of motion, and biological motion detection in noise. Testing was performed binocularly at 0 and 15 degrees of eccentricity. Mesopic conditions were achieved using neutral density filters and 15 minutes dark adaptation. The maximum luminance for the photopic and mesopic conditions were 200 cd/m2 and 0.54 cd/m2 respectively. Conditions were compared using a mixed ANOVA (factors: age group, eccentricity, and lighting).
Mesopic conditions elevated contrast thresholds for motion direction discrimination for both groups (F(1,34)=103.79, p<0.001), particularly in central vision (F(1,34)= 15.93, p<0.001) and more so for younger adults (F(1,34)=12.94, p=0.001). Global motion coherence thresholds were elevated under mesopic conditions (F(1,34)= 11.07, p=0.002), particularly for older adults in peripheral vision (interaction between group, lighting and location: F(1,34)= 5.15, p=0.03). Older adults showed increased surround suppression of motion peripherally (F(1,34)=7.18, p=0.01) for both light conditions. Both groups showed poorer ability to discriminate biological motion from noise in mesopic conditions at both eccentricities (F(1,33)= 6.57, p= 0.015).
Overall, changing from photopic to mesopic conditions impacted most motion perception tasks similarly for younger and older adults. A notable exception was global motion coherence thresholds, where under mesopic vision the deterioration in performance centrally was evident in both groups, whereas peripherally older adults demonstrated poorer performance relative to younger adults.
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