Visual function, especially with respect to its temporal characteristics, is believed to deteriorate over the life span. However, the time course, topographical patterns, and mechanisms of age-related loss of function are largely unknown. We examined the dynamic visual field properties of a large sample of normally sighted subjects to obtain normative data across the life span. We mapped characteristics of visual function in 95 healthy subjects between 10 and 90 years of age. Topographical measures included: luminance thresholds (static perimetry), temporal resolution (double-pulse resolution, DPR), reaction times (RT), and contrast thresholds for character recognition (R_contrast). In addition, a variety of non-topographical visual and attentional functions were determined (e.g. saccadic exploration, alertness).
DPR thresholds increased slightly but significantly with eccentricity and age, and the periphery showed a more pronounced age-related increase than the center. RT increased only slightly and uniformly across the visual field with age. Luminance thresholds in perimetry increased in a pattern similar to that observed for DPR. Performance in one measure at a given visual-field position allowed no prediction on performance in another measure. Correlations between visual-field means of the topographical measures were partially mediated by age. Contrast thresholds, alertness, divided and spatial attention, and saccadic exploration showed age-related changes and complex correlation patterns with the main outcome variables.
An age-related performance decrease was confirmed, but age was mostly a poor predictor of functionality because of high inter-individual variability. Age is, however, an intervening variable for the correlation between visual-field means of different functions. Retinal and optic media properties alone cannot explain the decline, but maps are also shaped by higher visual and cognitive function. The low point-by-point (local) correlations between topographical measures suggest separate underlying mechanisms of RT, DPR, and perimetry. The dataset constitutes a normative basis for psychophysical and neuropsychological studies.
Study supported by a grant of the Deutsche Forschungsgemeinschaft (Str 354/3-1) to HS.