From light to optic nerve: optimization of the front end of visual systems

Blindness is nature is fatal. In biology and physiology one finds many situations where nature has obtained neat solutions to problems, solutions that ar every nearly the best possible. Many of the design parameters for the eye are not arbitrarily selected, but are constrained to a narrow range of values by physics and information theory considerations. As Helmholtz mentioned more than a century ago 'the eye has every possible defect that can be found in an optical instrument and even some which are peculiar to itself; but they are all so interacted, that the inexactness of the image which results from their presence very little exceeds, under ordinary conditions of illumination, the limits which are set to the delicacy of sensation by the dimensions of the retinal cones.' Helmholtz was particularly prescient in his reference to cone dimension because, as we will see, many eye properties are completely determined once cone diameter is selected. The ideas presented in this paper are based on the working assumption that the eye does the best possible job within physical limits. This idea originated with Horace Barlow more than 40 years ago. Once excellent reference is the proceedings of a conference organized to honor Barlow's retirement with presentations by his many collaborators over the years. The list includes practically everyone referenced in this paper, which explores the design and optimization of the optics of the eye, retinal transduction and coding of visual data.