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Novel high-resolution microscopic techniques have been utilized to characterize the spatial distribution of orange emitting fluorophores, e.g., A2E, in lipofuscin granules isolated from human retinal pigment epithelium cells. Granules have been imaged using atomic force microscopy (AFM) and near-field scanning optical microscopy (NSOM). Near-field scanning optical microscopy images of lipofuscin show that the orange fluorophores, including A2E, are not major components of the granule. These results suggest that the orange fluorophores may not be the dominant photoactive species in lipofuscin.

The radical cations of five dietary carotenoids have been shown to react with dopamelanin (a model of the black eumelanin) and cysteinyldopamelanin (a model of the red/yellow pheomelanin) in both micellar and homogeneous environments. It is suggested that such repair reactions show previously unidentified protective roles for melanin/carotenoid combinations, especially where the maintenance of the (small) carotenoid concentration is vital to avoid deleterious effects, such as in the retina of the eye.