flavin-adenine-dinucleotide and Retinal-Diseases

To establish that increased autofluorescence of mitochondrial flavoproteins, an indicator of mitochondrial oxidative stress, correlates with retinal cell dysfunction.. Retinal flavoprotein autofluorescence (FA) was imaged in humans with a fundus camera modified with 467DF8-nm excitation and 535-nm emission filters and a back-illuminated, electron-multiplying, charge-coupled device camera interfaced with a computer equipped with customized image capture software. Multiple digital images, centered on the fovea, were obtained from each eye. Histograms of pixel intensities in grayscale units were analyzed for average intensity and average curve width. Adults with diabetes mellitus, age-related macular degeneration (ARMD), central serous retinopathy, and retinal dystrophies, as well as healthy control volunteers, were imaged. Monolayers of cultured human retinal pigment epithelial (HRPE) cells, HRPE cells exposed to sublethal doses of H2O2, and HRPE cells exposed to H2O2 in the presence of antioxidants were imaged for FA using fluorescent photomicroscopy.. Control patients demonstrated low levels of retinal FA, which increased progressively with age. Diabetics without visible retinopathy demonstrated increased FA levels compared to control volunteers (P < .001). Diabetics with retinopathy demonstrated significantly higher FA values than those without retinopathy (P < .04). Patients with ARMD, central serous retinopathy, or retinal dystrophies also demonstrated significantly increased FA. Compared to control RPE cells, cells oxidatively stressed with H2O2 had significantly elevated FA (P < .05), which was prevented by antioxidants (P < .05).. Retinal FA is significantly increased with age and diseases known to be mediated by oxidative stress. Retinal FA imaging may provide a novel, noninvasive method of assessing retinal health and retinal dysfunction prior to retinal cell death.

Topics: Acetylcysteine; Adult; Aged; Antioxidants; Apoptosis; Cells, Cultured; Ceramides; Flavin-Adenine Dinucleotide; Fluorescence; Humans; Hydrogen Peroxide; Middle Aged; Mitochondria; Photography; Retina; Retinal Diseases; Retinal Pigment Epithelium; Sphingosine

The detection of metabolic changes opens the possibility for intervention of reversible pathological alterations. Measurements of oxygen saturation are limited to the blood vessel system. Detection of alterations in oxygen concentrations are up to 3 orders of magnitude more sensitive by autofluorescence of coenzymes than by measurement of oxygen saturation. Because of limited transmission of the ocular media no specific excitation of endogenous fluorophores can be realised. For this reason it was investigated if the fluorescence lifetime after pulse excitation can be detected at the human fundus. Applying a laser scanner ophthalmoscope and mode-locked Ar(+) laser as well as time-correlated single photon counting, lifetime images of the living fundus were obtained. In mono-exponential approximation, a mean lifetime of 5 ns was detected from the optic disc and large vessels whereas about 1.5 ns were detected in the parapapillary area. By evaluating the frequency of lifetimes, lipofuscin, free FAD, and collagen are probably detectable. Comparative measurements were performed in fundus specimens and on free FAD.

Topics: Collagen; Energy Metabolism; Flavin-Adenine Dinucleotide; Fluorescein Angiography; Humans; Lipofuscin; Microscopy, Confocal; Ophthalmoscopy; Optic Disk; Oxygen Consumption; Retina; Retinal Diseases; Sensitivity and Specificity