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Fundus Autofluorescence and RPE Lipofuscin in Age-Related Macular Degeneration.

Sparrow JR, Duncker T - J Clin Med (2014)

Bottom Line: SW-AF imaging is currently used in the clinical management of retinal disorders and the advantages of NIR-AF are increasingly recognized.Here we visit the damaging properties of RPE lipofuscin that could be significant when expressed on a background of genetic susceptibility.To advance interpretations of disease-related patterns of fundus AF in AMD, we also consider the photochemical and spectrophotometric features of the lipofuscin compounds responsible for generating the fluorescence emission.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Ophthalmology, Columbia University Medical Center, 635 W. 165th Street, New York, NY 10032, USA ; Department of Pathology and Cell Biology, Columbia University Medical Center, 630 168th Street, New York, NY 10032, USA.

ABSTRACT
Genes that increase susceptibility to age-related macular degeneration (AMD) have been identified; however, since many individuals carrying these risk alleles do not develop disease, other contributors are involved. One additional factor, long implicated in the pathogenesis of AMD, is the lipofuscin of retinal pigment epithelium (RPE). The fluorophores that constitute RPE lipofuscin also serve as a source of autofluorescence (AF) that can be imaged by confocal laser ophthalmoscopy. The AF originating from lipofuscin is excited by the delivery of short wavelength (SW) light. A second autofluorescence is emitted from the melanin of RPE (and choroid) upon near-infrared (NIR-AF) excitation. SW-AF imaging is currently used in the clinical management of retinal disorders and the advantages of NIR-AF are increasingly recognized. Here we visit the damaging properties of RPE lipofuscin that could be significant when expressed on a background of genetic susceptibility. To advance interpretations of disease-related patterns of fundus AF in AMD, we also consider the photochemical and spectrophotometric features of the lipofuscin compounds responsible for generating the fluorescence emission.

No MeSH data available.


Related in: MedlinePlus

Short-wavelength (SW-AF) and near-infrared (NIR-AF) fundus autofluorescence. Images were obtained with 488 nm (SW) and 787 nm (NIR) excitation.
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Figure 1: Short-wavelength (SW-AF) and near-infrared (NIR-AF) fundus autofluorescence. Images were obtained with 488 nm (SW) and 787 nm (NIR) excitation.

Mentions: The natural autofluorescence of the fundus that is excited by SW light (488 nm excitation) (Figure 1) exhibits spectral features and an age-relationship that indicates a principle origin from the fluorescent pigments that accumulate in RPE cells as lipofuscin [17]. Unlike lipofuscin species that accumulate in other non-dividing cells, the pigments of RPE lipofuscin are produced in the membranes of photoreceptor outer segments from non-enzymatic reactions of vitamin A aldehyde [18–21]. This fluorescent material is transferred to RPE cells within phagocytosed outer segment disks [22, 23] and becomes deposited in the lysosomal compartment of the cells. In the healthy retina, fundus autofluorescence increases linearly with age although subjects vary in terms of intensities [11]. The age-related increase levels off after age 70 perhaps because of a loss of photoreceptor or RPE cells [24] and/or changes in fluorescence emission due to extensive photooxidation/photodegradation of the bisretinoid compounds [25] (discussed below).


Fundus Autofluorescence and RPE Lipofuscin in Age-Related Macular Degeneration.

Sparrow JR, Duncker T - J Clin Med (2014)

Short-wavelength (SW-AF) and near-infrared (NIR-AF) fundus autofluorescence. Images were obtained with 488 nm (SW) and 787 nm (NIR) excitation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4358814&req=5

Figure 1: Short-wavelength (SW-AF) and near-infrared (NIR-AF) fundus autofluorescence. Images were obtained with 488 nm (SW) and 787 nm (NIR) excitation.
Mentions: The natural autofluorescence of the fundus that is excited by SW light (488 nm excitation) (Figure 1) exhibits spectral features and an age-relationship that indicates a principle origin from the fluorescent pigments that accumulate in RPE cells as lipofuscin [17]. Unlike lipofuscin species that accumulate in other non-dividing cells, the pigments of RPE lipofuscin are produced in the membranes of photoreceptor outer segments from non-enzymatic reactions of vitamin A aldehyde [18–21]. This fluorescent material is transferred to RPE cells within phagocytosed outer segment disks [22, 23] and becomes deposited in the lysosomal compartment of the cells. In the healthy retina, fundus autofluorescence increases linearly with age although subjects vary in terms of intensities [11]. The age-related increase levels off after age 70 perhaps because of a loss of photoreceptor or RPE cells [24] and/or changes in fluorescence emission due to extensive photooxidation/photodegradation of the bisretinoid compounds [25] (discussed below).

Bottom Line: SW-AF imaging is currently used in the clinical management of retinal disorders and the advantages of NIR-AF are increasingly recognized.Here we visit the damaging properties of RPE lipofuscin that could be significant when expressed on a background of genetic susceptibility.To advance interpretations of disease-related patterns of fundus AF in AMD, we also consider the photochemical and spectrophotometric features of the lipofuscin compounds responsible for generating the fluorescence emission.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Ophthalmology, Columbia University Medical Center, 635 W. 165th Street, New York, NY 10032, USA ; Department of Pathology and Cell Biology, Columbia University Medical Center, 630 168th Street, New York, NY 10032, USA.

ABSTRACT
Genes that increase susceptibility to age-related macular degeneration (AMD) have been identified; however, since many individuals carrying these risk alleles do not develop disease, other contributors are involved. One additional factor, long implicated in the pathogenesis of AMD, is the lipofuscin of retinal pigment epithelium (RPE). The fluorophores that constitute RPE lipofuscin also serve as a source of autofluorescence (AF) that can be imaged by confocal laser ophthalmoscopy. The AF originating from lipofuscin is excited by the delivery of short wavelength (SW) light. A second autofluorescence is emitted from the melanin of RPE (and choroid) upon near-infrared (NIR-AF) excitation. SW-AF imaging is currently used in the clinical management of retinal disorders and the advantages of NIR-AF are increasingly recognized. Here we visit the damaging properties of RPE lipofuscin that could be significant when expressed on a background of genetic susceptibility. To advance interpretations of disease-related patterns of fundus AF in AMD, we also consider the photochemical and spectrophotometric features of the lipofuscin compounds responsible for generating the fluorescence emission.

No MeSH data available.


Related in: MedlinePlus