A COVARIANCE STRUCTURE-ANALYSIS OF FLICKER SENSITIVITY

We tested whether linear structural models of the mechanisms underlyin g flicker sensitivity could reproduce the variance-covariance matrix o f temporal contrast sensitivity data. Monocular sensitivities to frequ encies between 2.5 and 45 Hz were measured for 124 subjects, ages 18-8 8 yr. Exploratory factor analyses revealed that both a two-mechanism a nd a three-mechanism model could adequately account for the data. Furt hermore, confirmatory factor analyses and full structural equation mod els, using age as an explanatory variable, supported both models, with the three-factor model giving a somewhat better representation of the data. Parsimony favors the two-mechanism model. But patterns of loss associated with pre-exudative age-related maculopathy are more easily understood in terms of three underlying mechanisms.