Review of fundus autofluorescence in choroidal melanocytic lesions

Abstract

Fundus autofluorescence (FAF) imaging takes advantage of the fluorescent properties of some molecules, especially lipofuscin. FAF derives mainly from retinal pigment epithelium (RPE) and Bruch's membrane. Using confocal scanning laser ophthalmoscope (cSLO) we have previously shown that FAF associated with pigmented choroidal lesions can be attributed to mainly lipofuscin (orange pigment) within the RPE. Other causes of FAF include hyperpigmentation, drusen, or fibrous metaplasia probably because they also cause lipofuscin accumulation in the overlying RPE. There is a total or partial correlation between FAF and the foci of lipofuscin and hyperpigmentation in about 90% of the cases. The FAF patterns of choroidal melanocytic lesions were classified as patchy or diffuse. The patchy pattern was defined as the presence of distinct areas of increased FAF between areas of normal autofluorescence. The diffuse pattern was characterized by the presence of increased FAF with indistinct borders over a larger part (450%) of the tumour in the absence of such intervening areas. Choroidal melanomas presented with either a diffuse or patchy pattern, whereas choroidal naevi demonstrated only the patchy pattern. Diffuse FAF pattern was more often associated with larger choroidal melanomas as well as with early venous and late hyperfluorescence on fluorescein angiography. Limitations of these observations depend on the field of depth of cSLO; thus, FAF from other planes could not be detected. Increased retinal thickness, intraretinal oedema, or presence of subretinal fluid may also affect the FAF signal.

Using risk factors for detection and prognostication of uveal melanoma

“…Gunduz et al . [ 20 ] classified the FAF patterns of choroidal melanocytic lesions as patchy or diffuse. The patchy pattern was defined as the presence of distinct areas of increased FAF between areas of normal autofluorescence.…”

Blue-Light Fundus Autofluorescence Imaging following Ruthenium-106 Brachytherapy for Choroidal Melanoma

“…In general, FAF imaging gives additional important information beyond fundus photography, fluorescein angiography, and OCT in various retinal diseases [37,55]. While interpreting FAF images of choroidal melanomas we need to consider that the tumour itself does not contain any fluorophores as fluorescence microscopic examinations did not find autofluorescence in melanomas themselves [43]. From clinical aspects, we could confirm former reports that the untreated tumours were associated with laminar decreased FAF based on secondary RPE alterations overlying the choroidal melanoma, especially the tumour apex [41-43, 56, 57].…”

“…Besides, FAF imaging using a confocal scanning laser ophthalmoscope detects light reflected from the focal plane, whereas light from retinal structures outside the focal plane is suppressed by a pinhole aperture in order to enhance image contrast. Prominent lesions are not ideally capable of being examined by a confocal system, because structures from out of the focus might not be recorded properly [43]. In addition, FAF from deeper layers cannot be detected.…”

“…In any case, the molecular analysis of LF revealed non-degradable LF pigments being a by-product of phagocytosis of photoreceptor outer segments [30][31][32][33][34]. FAF examination using confocal scanning laser ophthalmoscopy (cSLO) is well established for the diagnosis and follow-up of various retinal diseases [35][36][37][38][39][40] and has also been used to describe FAF phenomena linked to choroidal melanomas [41][42][43]. FAF changes in choroidal pigmented lesions have been associated with orange pigment, hyperpigmentation, chronic changes of the overlying RPE, drusen, and fibrous metaplasia [43][44][45].…”

Multimodale Bildgebung des Aderhautmelanoms mit seinen Differenzialdiagnosen, Therapie (Bestrahlungsplanung) und Verlaufskontrolle

“…Generell ist die Autofluoreszenz der Netzhaut durch die stimulierte Emission von natürlich vorkommenden Fluorophoren bedingt, wobei das am meisten signifikante das Lipofuszin ist. Dieses besteht aus Lipiden, Proteinen und N-retinyl-N-Retinyliden-Ethanolamin, wobei der letzte Bestandteil als Nebenprodukt der Phagozytose der äußeren Segmentphotorezeptoren erachtet wird [11]. Man hält die Akkumulation von Lipofuszin für eine beeinträchtigte oder vermehrte lysosomale Aktivität mit inkompletter Degeneration und es konnten verschiedene Arten von Lipofuszin nachgewiesen werden [12,13].…”