Color-matching techniques were used to follow the course of central serous retinopathy in thirteen patients. During periods of neurosensory detachment?, cone optical densities were low. In some patients optical densities remained low following clinical resolution of the disease. In addition, abnormalities of bleaching were observed for one patient in one eye that appeared clinically unaffected during a period of detachment of the fellow eye. Analysis of the data indicates that for longitudinal measurements of optical density, standard Nagel anomaloscope matches can provide an accurate estimate of changes in foveal optical density, although they cannot provide a measure of the absolute optical density.