Quantitative evaluation of fundus autofluorescence imaged "in vivo" in eyes with retinal disease

Abstract

Aim-To describe a new method of evaluating the topographic distribution of fundus autofluorescence in eyes with retinal disease. Methods-Images of fundus autofluorescence were obtained in five patients and 34 normal volunteers using a confocal scanning laser ophthalmoscope (cSLO). To evaluate the topographic distribution of fundus autofluorescence throughout the posterior pole a rectangular box, 10 × 750 pixels, was used as the area of analysis. The box was placed, horizontally, across the macular region. The intensity of fundus autofluorescence of each pixel within the rectangular box was plotted against its degree of eccentricity. Profiles of fundus autofluorescence from patients were compared with those obtained from the age matched control group and with cSLO images. Results-Profiles of fundus autofluorescence appeared to represent the topographic distribution of fundus autofluorescence throughout the posterior pole appreciated in the cSLO images, and allowed rapid identification and quantification of areas of increased or decreased fundus autofluorescence. Conclusions-Fundus autofluorescence profiles appear to be useful to study the spatial distribution of fundus autofluorescence in eyes with retinal disease. (Br J Ophthalmol 2000;84:741-745) The study of accumulation of lipofuscin in the retinal pigment epithelium (RPE) has attracted the attention of many researchers in the past decades. Although still incompletely understood, it is believed that lipofuscin represents the end product of phagocytosed photoreceptor outer segment discs, and to a lesser extent, of autophagy.1-6 "Ex vivo" studies in donor human eyes have shown that lipofuscin accumulates in the RPE with age 7-9 and retinal disease. [10][11][12][13][14][15][16][17][18] Similarly, it has been demonstrated that, in normal subjects, there is a topographic distribution of RPE lipofuscin content throughout the fundus, being higher at the posterior pole, with a localised dip at the fovea, and lower towards the peripheral retina. [7][8][9] Excessive accumulation of lipofuscin in the RPE has been associated with degeneration of RPE cells and photoreceptors. 17 19 Hence, information regarding the distribution of fundus autofluorescence may provide insight on the sequence of events that lead to retina damage in a variety of retinal diseases. Until recently, information regarding the content and spatial distribution of RPE lipofuscin in eyes with retinal disease was limited by the scarce number of eyes available for histopathological evaluation. This problem has been recently overcome with the development of new techniques that allow the study of RPE lipofuscin levels "in vivo". 20-25Using a spectrophotometer 20-22 and a confocal scanning laser ophthalmoscope (cSLO) 23-25 the level of fundus autofluorescence (index of RPE lipofuscin content) has been assessed "in vivo" in a variety of retinal disorders. Previous in vivo studies have quantified fundus autofluorescence in eyes with retinal disease at selected areas of the retina. [20][21][22][2...

Quantitative Fundus Autofluorescence in Mice: Correlation With HPLC Quantitation of RPE Lipofuscin and Measurement of Retina Outer Nuclear Layer Thickness

“…12,13 Fundus AF imaging by cSLO also has aided the characterization of retina in animal models. 14-16 Several therapeutic strategies aimed at alleviating vision loss in recessive Stargardt disease have been tested preclinically in Abca4 À/À and Rdh8 À/À Abca4 À/À mice.…”

Macular autofluorescence in eyes with cystoid macula edema, detected with 488 nm-excitation but not with 580 nm-excitation

“…Fundus autofluorescence (AF) has been studied clinically and histologically [1][2][3][4][5][6][7][8][9][10][11][12]. Autofluorescence of the fundus is thought to be mainly a property of the retinal pigment epithelium (RPE), particularly reflecting the existence of lipofuscin, a pigment that is a by-product of phagocytosis of photoreceptor outer segments [11,[13][14][15].…”

Transient Pupillary Light Reflex in Relation to Fundus Autofluorescence and Dark-Adapted Perimetry in Typical Retinitis Pigmentosa

“…The major fluorophore (lipofuscin) accumulates in the RPE and is derived from the photoreceptor outer segment. Low-level or absent AF represents RPE loss or atrophy in eyes with RP, and can be correlated with an absolute scotoma for the patient [12] . Abnormally high levels of AF indicate abnormal metabolism: a high turnover of photoreceptor outer segments, disrupted phagocytosis or an intrinsic defect in the ability of the RPE to recycle metabolites.…”