Currently he works at the University Eye Clinic Maastricht. He studies the functional morphology of the human retina by noninvasive optical techniques. Models for spectral fundus reflectance have been developed, which yield individual estimates of the photoreceptor quality and the density of the dfferent absorber in the eye (lens, macular pigment,visual pigment, melanin). Recent work involves epidemiological studies on the relation between nutrition, macular pigment and age-related eye diseases.