Critical Flicker Fusion Scores Across Stimulus Luminance Ranges in Young and Old

Abstract

Purpose : Critical flicker fusion (CFF) is a measure of visual processing speed that has been shown to correlate with age-related changes in visual function(Maier et al, 2010). The relationship between CFF and luminance levels was examined in young and older subjects to determine if age-related deficits in CFF are dependent on luminance level of presented stimuli.

Methods : The Lafayette Instruments flicker fusion system was used to test CFF at ten luminance levels , including photopic (44-0.88 candela/meter²), mesopic (0.044-0.0022 cd/m²) and scotopic (0.0022-0.00022 cd/m²) light levels. A staircase protocol employed increasing and decreasing luminance CFF tests, with average values calculated at each level. Both eyes were included in testing. A 45-minute dark adaptation was performed for the scotopic and lowest two mesopic levels. Subjects (n=18) were selected to provide representation of a range of ages; analysis was based on 2 age groups, < 70 years (n=9, mean age 42.2) and ≥ 70 years (n=9, mean age 73.2).

Results : The CFF scores for all subjects were directly correlated with the stimulus luminosity. Comparisons of mean CFF for the two age groups exhibited the greatest difference at the brightest photopic luminance levels, but were statistically different at all levels from 44 to 0.044 cd/m²(p values all ≤ 0.00022). No statistically significant differences were observed between the two age groups in the lower mesopic range.

Conclusions : Greatest differences in CFF between younger and older subjects are observed with stimuli in the photopic and upper mesopic ranges. CFF measured with photopic luminance stimuli may be optimal for testing age-related flicker sensitivity changes.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.