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Maria F. Loureiro, Catarina Mateus, Barbara Oliveiros, Raquel Lemos, Aldina Reis, Miguel Castelo-Branco; Magno- And Dorsal Stream Processing Decline Slower Than Parvocellular Performance In Normal Aging. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6397.
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© ARVO (1962-2015); The Authors (2016-present)
Gradual decline of visual function in the absence of any recognizable disease is a normal part of human retina aging. In fact, it is the result of optical factors, neuronal cell loss and changes in central visual pathways. Our aim was to analyze the effect of age in visual performance within multiple visual channels (magno-, parvo- and koniocellular) using tests that tackle their function in an independent manner.
Five psychophysical tests, namely Frequency-Doubling Technology (FDT: n = 158 eyes; mean age: 41.68 ± 1.26 [SEM] years), Local Speed Discrimination Test (LocSp: n = 97 eyes; 45.36 ± 1.62 years), 3-D Structure from Motion (SFM: n = 98 eyes; 45.39 ± 1.60 years), Cambridge Color Test (CCT: n = 135 eyes; 39.65 ± 1.35 years) and Intermediate Spatial Frequency Perimetry (ISF: n = 165 eyes; 39.81 ± 1.21 years), were performed in controls with ages between 20 and 83 years. Age groups were defined by decades above 20 years.
We found significant correlations between age and all functional performance values (achromatic contrast sensitivity/motion perception and chromatic contrast), except for deutan chromatic thresholds. FDT showed a linear sensitivity loss of 0.75 dB per decade (p<0.001; adjusted R2 = 0.17). Concerning LocSp, performance decreased around 2.71º/s (p<0.001; adjusted R2 = 0.17) per decade for the horizontal meridian and 3.15º/s (p<0.001; adjusted R2 = 0.13) for the oblique meridian (but only for stimulus presentation of 400 ms). With 3-D SFM a more evident decrease of motion perception per age group was found in the temporally constrained integration condition of 200 ms (about 6.4% of coherence; p<0.001; adjusted R2 = 0.51). Using ISF perimetry, mean contrast sensitivity decreased linearly 2.35 dB (p<0.001; adjusted R2 = 0.55) per age group. Regarding CCT, significant linear regressions were found for protan (1.52 CIE u’v’ color space units per decade, p= 0.023 with adjusted R2 = 0.03) and tritan (3.05 per age group, p= 0.004 with adjusted R2 = 0.055).
These findings suggested that functional visual performance thresholds mediated by parvocellular pathway and dorsal stream processing (with temporally constrained integration task) were more affected by age than those mediated by magno- and koniocellular pathways.
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