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Retinal Ganglion Cells and Melanopsin

by David M. Keith

Retinal ganglion cells are involved in the processing of visual information, and the varying ratio of photoreceptors to each cell is related to visual sensitivity across the retina.

Since 2002, information has been developed about the role of retinal ganglion cells in the control of melatonin. Dr. Pauley's summary of the science as of 2004 is available from Medical Hypotheses (v63i4 Pages 588-596). Based on published data, in 2004 J. Hollan developed a corresponding action spectrum for this "non-visual photoreceptor" - melanopsin - which responds to radiation but does not contribute to the visual image. The following diagram shows the relative sensitivity of melanopsin as the blue line on the left side, along with the conventional photopic (white and gray) and scotopic (black) sensitivity functions.

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