Scanning pupils and squinting painters: Explorations in physiological optics Seminar

The image of the location to which the optic axis of the eye is directed is positioned in the centre of the pupil. However, because the visual axis of the eye deviates a few degrees nasally from the optic axis (angle alpha), this is not, as is sometimes erroneously assumed, the location to which fovea is directed. A further consequence is that the corneal reflex is located asymmetrically in the two eyes and this asymmetry is apparent in frontally viewed portrait photographs. I shall present some systematic measurements of the way in which the corneal reflex has been portrayed by portrait painters over the years from the second to the nineteenth century. These show that some famous painters generally record the asymmetry whereas others more often paint the highlights symmetrically. The approach can also contribute to the debate about whether certain artists, such as Dürer and Rembrandt, were strabismic.