Rethinking the Process of Vision

“Theory like mist on eyeglasses, obscures vision”
NY Times, July 4,2003, David Botstein (quoting from a Charlie Chan film)

“The real voyage of discovery consists not in seeking new landscapes but in seeing old landscapes with new eyes.”
Marcel Proust

I propose that the asymmetric organization of cones and rods on the retinal surface has heretofore unrecognized significance. This proposal is derived from the construction that light interactive outer segments of receptors are configured as a logical array of quantum confined electron sites with interreceptor spaces forming spatial (”antenna”) dimensionalities wherein light interacts in classical wave fashion. In this view the fundamental light detecting “devices” of the retina comprise two adjacent receptors and the variable widths between them and possess the capability for detecting both light amplitude and phase satisfying the Fourier equation. ALL receptors (both cone and rod!) then have one basic function - to act as generic, energy-accepting, quantum confined electron sites. It is interreceptor spacing defined by the spatial dimensions of the receptor inner segments that responds to wavelength.

Applying this construction to the well understood pattern of retinal organization and simply counting interreceptor dimensionalities, this surface is seen to form three distinct light sensitive rings (or bands) surrounding the central fovea to about 20 degrees. Very surprisingly, each of these bands is narrowly tuned (in antenna terms) precisely to three wavelengths. Three cardinal points are geometrically defined on the retinal surface - the exact long and short wavelength limits of the visible spectrum (700 and 400 nm) and, importantly, a location on the retinal surface (at 7 1/2 degrees) that defines the exact center of that spectrum (550 nm). A geometric explanation for the well documented trichromicity of visual response is therefore presented as well as a reason for the natural evolution of two sizes of receptors. Receptor size (specifically, the diameter of the inner segment) is the defining attribute that responds to wavelength and it is the ratio of two sizes (if such are present) that defines bandwidth. All of this follows from a simple geometrical construction.

The retina thus acts as a diffraction plane showing that it is the focal or Fourier plane (NOT the image plane) of the optical system of the eye. Image formation thus derives from detection of both light amplitude and phase information encoded on the retina as the Fourier equation requires (we indicate how the proposed retinal devices accomplish this task). Marr’s “primal sketch” is imaged as an optical transform at the long wavelength limit on the fovea.

This model provides verification for Edwin Land’s color vision experiments showing that “color” is not directly detected on the retina at all but this sensation derives from a “balance of signals” around the geometrically defined central point (at 7 1/2 degrees) and presented to the brain. The term “color” should not even be used in association with the retina!

I have come to believe that “wavelength discrimination” should not be associated with retinal action as the wavelengths presented to the retina are “pre-determined” by refraction in the lens and body of the eye (and directed into three discrete tuned bands). This leaves only quantum efficiency as the operative retinal parameter. The retina then acts as a “geometric intermediary (or transducer)” in the vision process between the process of “wavelength determination” and generation of the “color signal”. The visual system responds to wavelength before light interacts with the retina and is directed to antenna resonances on the retinal surface. Color is a result of signals synthesized by, and that “have left” the retina!

The actual function of the retina and that of its’ underlying neuro-circuitry now becomes clear - to wit, solely the arithmetic processing of discrete signals using the three geometrically defined cardinal points of the visible band in calculation of the final image and the “color” signals to be presented to the brain.

In light of the above, I believe that a “higher order” of thought is possible eliminating the need for a quest to understand the eye as a complex photometric imaging instrument - a task that has preoccupied science for a hundred years and that has led to so many illogical conclusions.

I believe that it is now possible to turn one’s attention to external reality beyond the eye.. what is actually perceived by the eye….as discussed so eloquently by Land. In the Fourier domain, retinal architecture must somehow correspond to the “diffraction pattern of perceived reality”. I am fascinated by the thought that as antennas are perfectly capable both of absorbing and radiating electromagnetic energy might the eye then not be the “passive optical receiver” that has for so long been assumed? Is it possible that the eye “radiates” some albeit photon level signal into the visible spectrum and that this might bear on what is perceived of external reality? Might such a “two way optical interrogation” of external reality bear on consciousness - at least via the visual pathway?