Fundamental Limits to Vision
David Williams
The organization of the visual system sets limits on our ability to see. Some of these limits arise at the very earliest stages of the visual pathway such as the optics of the eye and retina. My work is focused on understanding these limits and on developing new ways of overcoming them.
For example, I developed a new kind of laser interferometer that can produce very fine patterns on the retina, much finer than could ever be imaged there under ordinary viewing conditions. This device allowed me to reveal the limitations on spatial vision imposed by the photoreceptor mosaic. A current research project uses adaptive optics to correct the blurring ordinarily imposed by the optics of the eye. A deformable mirror is warped into just the right shape to compensate for the particular aberrations in individual human eyes, endowing the eye with unprecedented optical quality. This system will allow us not only to study neural mechanisms of spatial and color vision, but can also provide a clearer view of the inside of the human eye than has been heretofore possible. A camera we have equipped with adaptive optics can acquire sharper images of the retina than has been possible previously, sharp enough to resolve single cells in the living human retina. Another project has provided the first color images of the primate photoreceptor mosaic that allow one to distinguish the three cone types responsible for human color vision.