A method of identifying a human subject, more likely than a subject selected at random from the general population, to have one or more of the following: (i) a low macular pigment concentration in the eye or eyes (ii) a low visual performance, or (iii) an atypical “central dip” macular pigment distribution the method comprising the steps of: measuring at least one cognitive function of the subject comparing the measured cognitive function with a pre-determined threshold and, if the measured cognitive function is below the threshold, declaring the subject as being more likely to have one or more of low macular pigment concentration in the eye or eyes, low visual performance or an atypical ‘central dip’ macular pigment profile.
