UC Berkeley

The movements of the eye play an integral part in constructing a smooth perception of the world around us. The fact that our eyes are foveal, with a high resolution center and a radial decrease in resolution as we move away from this center, necessitates a constant shifting of our gaze around our environment. Although our eyes are in constant motion we do not perceive the world as a series of static snapshots and constant jitter, instead our visual system is able to effectively integrate information over time to render the world veridically; a complex array of color, depth, and motion. These eye movements are essential to vision for a wide variety of reasons. In fact, movement is such a key aspect of vision that if the projection of the world onto the retina is rendered perfectly still, our vision will slowly fade. Our brain relies on a constantly fluctuating signal in order to generate a visual percept, and without this temporal variation, vision is impossible. Even when fixating on a point, our eyes are still engaging in a series of small movements to examine and enhance the fine details of the foveated stimuli. Collectively, these small movements are referred to as fixational eye motion (FEM). In order to truly understand how these small temporal variations will contribute to vision, it is necessary to understand how these movements interact with the photoreceptors in the retina. To this end we utilized an Adaptive Optics Scanning Laser Ophthalmoscope to project stimuli onto the photoreceptor mosaic and simultaneously recover an unambiguous trace of the motion of these stimuli as the eye engages in fixational eye movements.