Photooxidation of RPE lipofuscin bisretinoids enhances fluorescence intensity

Light-related cycling of chemically reactive vitamin A aldehyde leads to the formation autofluorescent bis-retinoid pigments that accumulate as lipofuscin in retinal pigment epithelial cells. The amassing of these diretinoid compounds is implicated in the pathogenesis of age-related macular degeneration and in some inherited forms of retinal degeneration. For all of these fluorophores, extended conjugation systems confer absorbance maxima in the visible spectrum. We report that an increase in fluorescence emission can accompany photoxidation of the bisretinoids A2E and all-trans-retinal dimer. These findings are relevant to the quantification of RPE lipofuscin based on inference from fluorescence intensity.