Op art works tend to be abstract geometrical designs, but this need not be the case. This design presents a metaphorical eye and brain. The central radiating lines are like light rays that enter the eye through a small aperture and then strike the retina. Within the retina there are three neural levels consisting of receptors, bipolar cells and retinal ganglion cells &mdash all of which have lateral connections. The axons from the ganglion cells travel to the visual cortex, undergoing partial separation so that the left and right hemiretinae project to opposite hemispheres. In the central region the circles represent the two overlapping monocular visual fields, in which there is binocular brightness enhancement.