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Number of photons that must enter the eye in order to generate an observed reproducible physiological response

Range	~100 photons
Organism	Human Homo sapiens
Reference	Stuart JA, Brige RR (1996). "Characterization of the primary photochemical events in bacteriorhodopsin and rhodopsin". In Lee AG. Rhodopsin and G-Protein Linked Receptors, Part A (Vol 2, 1996) (2 Vol Set). Greenwich, Conn: JAI Press. pp. 33–140. ISBN 1-55938-659-2. p.40 & p.104 top paragraph
Comments	"In practice, ~ 100 photons must enter the eye in order to generate an observed reproducible physiological response. Light adaptation decreases this sensitivity level further...[researchers] can reliably detect pulses of light that send roughly 100 photons through the pupil and activate approximately 10-20 rhodopsin molecules in as many rod photoreceptors."
Entered by	Uri M
ID	110983