A major goal is to relate visual function to macular appearance for people aged 60 and older 1) for normative purposes and 2) to determine risk factors for exudative aging macular degeneration (AMD). To establish relationships prospectively, the current cross-sectional study will be converted to a longitudinal study of eyes which at initial testing had good acuity and good ocular health, except perhaps for macular drusen or pigmentary change. Two groups of eyes will be studied: eyes whose fellow eye had good acuity at initial testing; and eyes whose fellow eye had exudative AMD. The visual functions to be measured are those for which eyes in the former group scored better than eyes in the latter group. Those functions are a) S cone sensitivity, b) absolute photopic threshold, c) photopic dark adaptation and d) the anomaloscope color match area effect. Fundus photographs will be scored for features which may be associated with future AMD. These features include a) number, size and distribution of macular drusen, b) confluence of drusen and c) presence of focal hyperpigmentation. Estimates of lens and macular pigment densities will be derived and compared with potential indices of phototoxic retinal insult. The goal of the basic laboratory research is to provide a framework for and an explanation of the plateaus and losses of foveal sensitivity found midway through the period of dark adaptation for certain sets of bleaching and testing parameters, including those used in the studies of aging. The research is intended to a) define the parameters for which recovery of sensitivity is nonmonotonic b) determine the extent to which parallel channel models of visual sensitivity are compatible with different types of dark adaptation data and c) provide constraints and specify sites and mechanisms which may influence the rate of change of sensitivity during dark adaptation. Psychophysical and physiological models will be evaluated with spectral sensitivity and temporal integration data obtained using conventional test stimuli of different durations, with spectral sensitivity data obtained using low spatiotemporal frequency stimuli and rapidly flickering stimuli, and with color matching data obtained during periods of monochromacy. Dichromats will be tested to separate the effects of rod/cone interactions from those of cone spectral opponency. The plateaus and losses of sensitivity after different bleaches will be used as markers to distinguish between different possible causes of postreceptoral desensitization.
