Table 1.

Endogenous fluorophores responsible for autofluorescence in the retina and nearby tissue.

Fluorophore	Excitation, nm	Emission, nm	Lifetime, ns	References
phenylalanine	258 (max) 240-270	280 (max)	7.5	(McGuinness et al., 2006)
tyrosine	275 (max) 250-290	300 (max)	2.5	(Ashikawa et al., 1982)
tryptophan	280 (max) 250-310	350 (max)	2.0–6.0	(Guo et al., 2012; Guo et al., 2013)
NAD(P)H free	300–380	450–500	0.3	(König, 2008)
NAD(P)H protein	300–380	450–500	2.0–2.3	(König, 2008)
FAD free	420–500	520–570	2.91	(Koziol et al., 2006; König, 2008)
FAD protein bound	420–500	weak in 520–570	<0.01	(Schweitzer et al., 2007b)
retinal (Shiff base)	350	600–650	0.030–0.1	(Bachilo and Gillbro, 1999)
hemoglobin	400–600	non-fluorescent	n/a	–
melanin	300–800	broad in NIR	0.65–1.6	(König, 2008)
collagen	280–350	370–440	≤5.3	(Maarek et al., 2000; König, 2008)
elastin	300–370	420–460	≤2.3	(Maarek et al., 2000; König, 2008)
lutein	440–540	550	0.03–0.08	(Barker et al., 2011; Dysli et al. 2016e)
zeaxanthin	440–540	550	0.03–0.08	(Barker et al., 2011; Dysli et al. 2016e)
lipofuscin	340–500	540,430-460	up to 2.2	(Sparrow et al., 2000; Schweitzer et al., 2007b)

Abbreviations: nicotinamide adenine dinucleotide (NADH); nicotinamide adenine dinucleotide phosphate (NADPH); flavin adenine dinucleotide (FAD); near-infrared autofluorescence (NIR); nanometer (nm); nanoseconds (ns).