Autofluoreszenz-Imaging der Makula

Abstract

Visualization of the retinal pigment epithelium (RPE) in vivo has proven difficult for various reasons, including the optical properties of the eye and the small size of the cellular elements, forming a single layer between the neurosensory retina and Bruch's membrane. With the advent of scanning laser ophthalmoscopy it is now possible to image topographic distribution and intensity fundus autofluorescence derived from accumulations of lipofuscin granules in RPE cells. Excessive lipofuscin storage in the RPE cytoplasm occurs not only in association with age but also with many hereditary and degenerative retinal diseases including age-related macular degeneration, Stargardt disease, Best disease, and pattern dystrophies. Lipofuscin in the RPE derives mainly from incomplete degradation of phagocytosed distal segments of photoreceptor outer segments, and is composed of various biomolecules including lipids, protein, and retinoids. Some of its constituents have recently been shown to possess toxic properties in vitro and may play a pathophysiological role in diseases such as age-related macular degeneration.Visualizing lipofuscin in vivo may help to better understand the significance of these metabolic alterations in the pathogenesis of retinal disorders. In addition,fundus autofluorescence imaging can be useful in the preclinical diagnosis of hereditary retinal disease. Dynamic alterations of intrinsic RPE fluorescence change may be applicable for monitoring effects at the level of the RPE of novel therapeutic modalities. Furthermore, identification of high-risk characteristics in patients with age-related macular degeneration with this technique may be helpful for indicating and adjusting future therapies.