THE RETINA AS AN ARRAY OF NANO-ANTENNAS

by Gerald Huth on January 13, 2011

The retina is actually composed of an array of nano-antennas and antennas interact with the wave nature of light. Moreover, only three geometrically defined antenna lengths form concentric radial bands surrounding the central fovea. The specific retinal antenna architecture is  as follows:

a.) A central all-cone fovea sensitive to and defining the precise long wavelength 700 nm limit of the visual band.

b.) As smaller rod receptors are introduced, a radial band extending from the edge of the fovea (1 degree) to approximately 10 degrees that is uniformly sensitive to the exact middle (550 nm) of the visual band. The peak of this band is at 7-8 degrees of retinal eccentricity.

c.) The retina beyond ~10 degrees where smaller rods  predominate that is sensitive to, and defines, the precise short wavelength (~400 nm) limit of the visual band.

In summary then, It would seem that the area of the retina involved in formation of the visual image extends from the fovea to ~20 degrees where a peak of short wavelength sites peaks.

The retina that surrounds this central imaging area extending to the ora serrata continues to be solely sensitive to the wavelength defining the short wavelength limit. I have proposed that this area acts as a wide angle “light meter” controlling pupillary constriction and limiting light entrance into the eye. It has long been known that receptors in this region, as opposed to in the more central retina, are “connected together” that would be necessary to provide the light meter function that I propose.

It is instructive that this light meter function is sensitive not only to intensity but it has also been found to be sensitive to wavelength (see references in the body of the work). I for one had always been taught that control of pupillary constriction was the sole province of light intensity. This means in the context of this work that the diameter of rods, in determining the rod appositional antenna distance, is the primary factor.

The following figure provides the fundamental basis for these findings. It represents using Oserberg’s 1935 accepted measurements of receptor distribution, a simple counting of receptor appositions (cone-cone. cone-rod and rod-rod)  as a function of retinal eccentricity. It is found that three distinct peaks emerge from what has historically been seen as a statistical receptor distribution. These three peaks represent three radial bands surrounding the central fovea:

These three peaks must not be confused with the historic (i.e., found in every textbook on vision) curves of the spectral distribution of “color sensitive cones”. The ordinate here is retinal eccentricity and not light wavelength.   These are radial bands of the density of nano-antenna light detection structures responsive to only three narrow wavelengths.

The central all-cone fovea with characteristic longest  (cone-to-cone appositions )antenna dimension is singularly responsive to the longest wavelength of the visual band – ~700 nm.  Or, it is the generally larger lateral dimension of cone receptors that determines the (precise) long wavelength limit of vision.

It follows then that the retina does not act as an optical wavelength spectrometer as has been historically assumed and shown over and over in texts on vision.

Geometry is the determining factor in response of the retina to the wavelength of light.

It is seen then that the three light interactive regions of the retina define the precise long and short wavelength limits and geometrically determined mid band of visual response.

These regions are in reality three narrow band optical filters.

The eye views external reality through these three optical filters.

And… the finding of the trichromicity of vision is preserved and fundamentally explained

Finally, I would be derelict not to present the historic curve of the spectral response of cones that are used to define vision.

I have shown this curve before with the red X making the point that “blue” sensitive cones do not exist (any short wavelength response in the region near the fovea is from the statistically rare rod-to-rod appositions that exist as rods are introduced into the retinal motif).

And….. noting again that Nobelist George Wald found the all-cone fovea to be “blue blind”…….

But please note that the ordinate of the curve is light wavelength and not, as the curve above, retinal eccentricity.

I have written previously about these curves of “color sensitive cones” to which the reader can refer.

For now…

GCH

Ojai,CA

1.13.11

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