The eye, ganglion cells, new photoreceptors

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For 150 years, rods and cones have been considered the only photoreceptors of the mammalian eye. For more than a decade, however, evidence has been mounting for the existence of other ocular photoreceptors. In my view this shows us how we can be so convinced of our scientific accuracy only to be disproved, this may well be the flaw with hard determinism which deals with a world on the atomic and subatomic levels and determinists seem to be convinced of our scientific correctness.

E.G. In recent years, scientists working at the intersection of two historically well-developed fields, retinal physiology and circadian biology, upended the conventionalview of retinal organization with the confirmation of a nonvisual ocular photoreceptorsystem.

The eye has been shown to have functions beyond image perception and this holds the potential to explain why a significant proportion of patients with progressive degenerative ocular disease suffer from sleep disturbances. An understanding of these non-rod/non-cone photoreceptors might also explain seasonal affective disorder (SAD), jet lag and depression in the blind. It has the potential to influence intraocular lens selection for cataract patients. “The shocker is, you don’t need rods and cones to synchronize your circadian clock to the local light-dark cycle,” said Russell N. Van Gelder, MD, PhD. “There’s this whole other photoreceptive system lurking in the retina entraining your circadian system.” Dr. Van Gelder is professor/chairman of ophthalmology at University of Washington in Seattle.

Recent reports have now established the identity of these novel retinal photoreceptors and has begun to delineate their photochemistry, anatomy, functional…


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