Rethinking the Process of Vision

First, I consider this work an ‘explanation’ rather than an ‘hypothesis’ or ‘theory’ that requires proof. A simple and rational reason is presented for the unique assymetrical arrangement of cones and rods that form the retinal surface..and this leads to a totally new understanding of the vision process. Why hasn’t anyone in the last hundred years observed that it is the geometric center-to-center distance between cone and rod retinal receptors (that is determined by receptor diameter) that defines where the wavelengths of light interact on the retinal surface? What has been termed an ‘aberration’ - lateral chromatic aberration - is not an aberration at all but is the primary wavelength-separating factor operating in the eye. Seen in this light, the strange, assymmetric organization of cones and rods that has evolved is immediately explained. The precise short and long wavelength endpoints, and an exact geometrically-defined midpoint, of the visible band are defined and their location actually delineated on the retinal surface. With this insight it becomes obvious that the retina is a circularly diffractomeric light interactive surface and that vision is a Fourier-transforming process. The eye is not a ‘camera’ nor is the retina the analogue of a section of photographic film!

I have proposed that if the Roorda group would apply the same retinal imaging methodology (1) that they used at one degree of retina angle to measurements of retinal response at seven degrees they would find that it was composed of all green-sensitive centers (that they would term the response of ‘cones’). In this explanation this would correspond to the response of cone-rod appositions whose density peaks at this angle.

(1) ”Packing arrangement of the three cone classes in primate retina”, Roorda et al, Vision Research, Vol.41, 1291-1306, (2001)

GCH

I have referenced on a number of occasions a paper by Brian Hagan (”THE MATHEMATICAL TRANSFORMATION OF GROWTH AND FORM: TRANFERRING THE WAVE-PARTICLE DUALITY FROM PHYSICS TO BIOLOGY AND PROPOSING WAVE INTERACTION AS A KEY DETERMINANT OF BIOLOGICAL STRUCTURE”, Medical Hypotheses, 6, 559-609, 1980). I do not believe that this very prescient paper has received the attention that it deserves. I highly recommend reading it!

Hagan was certainly among the first proposing that vision involves a Fourier transformation process. I will quote from that section (p.594) of his paper:

“The human eye has been seen by some investigators as a device for producing a Fourier transform of an object and of recovering the transform for presentation to the brain ( ref.Ochs). This recovery of the transform reproduces the object with which we are familiar, in contrast to the appearance of the intermediate or one-step stage with which we are less familiar (Figure 15)”

(The Ochs reference - “Is Fourier Analysis Performed by the Visual System or by the Investigator”, J. Opt. Soc. of Amer. 1979 - introduces the thought but goes on to say very little that is explanatory or substantive)

(Figure 15 is a usual diagram that I have often discussed diagramming the focal (or Fourier) and image planes of a converging lens).

Hagan goes further:

“There is no reason to doubt the existence in biological systems of a multiude of Fourier transforming devices which do not recover the image as the eye does, but leave it at the one-step intermediate or transform stage. Edges, holes, slits, reglar grids or any other type of discontinuity are examples of lensless agents wich can act as operators to form one-step Fourier transforms of objects (Figure..)”

This is an extraordinary proposal about which I will have more to say shortly.

GCH

An interesting research initiative at the University of Leipzig focuses on the convergence of technologies from microscopic to nanoscopic structures. I had concluded that such a dual view must be considered in the nanoscopic processes involved in light interaction with the human retina and the entirely separate microscopic process (based on the morphology or organization of retinal receptors) that the eye uses to form an image. I have discussed this subject in my past comments pointing out how the concept of a ‘color-sensing pigment interaction’, no matter how accurately described, would in any way go on to describe how an image is formed ….they are two entirely different subjects in different spatial domains!

One should stop and think how imprecise it is to say that a ‘cone receptor detects color’! Beyond the improper use of the term ‘color’ (often discussed in this work), this statement completely disregards any connection to how the eye forms an image leaving it to the reader’s imagination how this might happen….and leaving the false notion that the eye is some sort of ‘camera’. And yet this statement is repeated over and over in the literature of vision until it has become an unthinking mantra.

But…..the processes of light interaction with retinal receptors and the subsequent formation of the visual image are two separate subjects

Again for the record, my explanation is that, nanoscopically, the retina evolved to detect light as an electromagnetic wave in ‘optical antennas’ formed in the spaces between receptors subsequently transmitting the energy absorbed to quantum confined electron rhodopsin sites within each receptor. The image formation process based on the long accepted (Osterberg) , but never explained, microscopic arrangement of cones and rods that form the retina is shown to lie in the Fourier domain…..i.e., via a 2-D Fourier image transforming process.

GCH

Again from Erwin Schrodinger’s Mind and Matter:

“…Bees, for example, have a colour vision reaching well into the ultra-violet; they are true trichromates (not dichromates, as they seemed in earlier experiments which paid no attention to the ultra-violet)….”

Now, leaving aside for a moment the subject of tri- or di- chromicity, I would propose that the ultraviolet (UV) vision of this species results from their retinal receptors being of smaller diameter than the human variety. Such a smaller diameter will in turn result in smaller receptor-to-receptor appositional length extending the short wavelength limit of the bee’s visual response to shorter wavelengths (I don’t know if bees have cones and/or rods). In a cursory look at the literature this seems to be true although it bears more looking into. Someone?

As to the tri- or di- chromicity of bee’s vision, this will depend, following from my ideas, as to whether their retinas possess two distinct sizes (i.e., diameters) of receptors. It follows from my concept that only a retina composed of receptors of two (or more) sizes can have either type of chromicity, or, in fact, any color vision at all..

An interesting thought following from what I have been discussing lately about the consequences of extending the short wavelength end of the visual band into the higher energy radiation of the UV region and pointing out the possibility of the biological damage that might ensue. What are the implications as to biological damage of the UV vision of insects? Might their retinas possess some damage-inhibiting mechanism not possessed by humans (or might they just not live long enough!)? Might there be some lesson here relative to the prevention of the macular degeneration condition in human vision?

GCH