  Non-degradable fluorophores that accumulate as Lipofuscin in retinal pigment
epithelium (RPE) cells has been a major source of intrinsic biomarker for
quantifying the progression of several diseases, including age-related macular
degeneration, Stargardt disease and, more. Recent progression in quantifying
these diseases is entertained mostly by a few noninvasive imaging techniques,
relied either on the life-time of the retinoid-fluorophores or, their linear
and, non-linear absorption cross-sections. Apart from these intrinsic
properties, a native, excited state dipole-dipole interaction mediated typical
spectroscopic phenomenon that is excitation dependent emission-wavelength
shifting is observed from these bis-retinoid fluorophores. Here, we emphasize
the spectroscopic origin of this phenomenon and exploit one of its
associated-properties, that is built-in fluorescence anisotropy as a
noninvasive, in vivo imaging probe for bis-retinoid products in mouse eyes.
