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Maria Coward, Fuensanta A Vera-Diaz, Thanasis Panorgias; The Effect of Age on Parafoveal Chromatic Sensitivity. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4047.
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© ARVO (1962-2015); The Authors (2016-present)
Chromatic sensitivity declines with aging. Recent evidence suggests that age-related changes in the parafoveal retina occur earlier than in the fovea. We performed a cross-sectional study investigating the age-related decline in chromatic sensitivity foveally and parafoveally.
Ten older (55-65 years) and ten younger (20-30 years) subjects were tested. Inclusion criteria included normal color vision as tested with standard clinical tests (HRR#4 and Ishihara), best corrected acuity of 0.00 LogMAR or better in the tested eye, and no ocular abnormalities other than age appropriate lenticular changes. Subjects were dark adapted for 10 minutes and then instructed to fixate on a fixation point in the center of a monitor with a neutral background of luminance noise (20cd/m2 average luminance). The threshold was determined in CIE1976 u’v’ color space for four different chromatic axes (red, green, blue, yellow) that coincided with the physiological cardinal axes ((L-M) and (S-(L+M)), respectively) using a stimulus presented for 250 ms for three different eccentricities (0, 5 and 10 degrees). At 0 degrees eccentricity, the stimulus size was 2 degrees and was adjusted accordingly using the cortical magnification factor for the 5 and 10 degrees eccentricities. The threshold was tested using a 4-alternative forced-choice 2down/1up staircase. The threshold was determined using the last 5 reversals. Statistical analysis was conducted at a 90% confidence interval.
We found no significant difference in chromatic thresholds at the fovea between the younger and older subject groups along any of the four chromatic axes. At 5 degrees eccentricity, when compared to the older subjects, younger subjects showed significantly lower mean chromatic thresholds for the blue, yellow, and red cardinal axes (all p < 0.04), but not for green (p = 0.312). At 10 degrees eccentricity, younger subjects when compared to the older subjects showed significantly lower mean chromatic thresholds for the yellow (p <0.03) and blue (p < 0.08) cardinal axes.
Younger subjects have greater parafoveal, but not foveal, chromatic sensitivity compared to older subjects. It may be beneficial to use parafoveal rather than foveal chromatic sensitivity when diagnosing and monitoring early macular diseases. These results agree with hypotheses that the fovea has compensatory mechanisms that prevent functional decline despite structural changes.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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