Fundus autofluorescence (AF) plays an increasingly important role in our understanding of retinal degenerative disease (RDD) and other retinal disorders. One of the earliest detectable disease markers in age-related macular degeneration (AMD) and other retinal degenerations such as Stargardt disease (STGD) and retinitis pigmentosa (RP) is abnormal accumulation of lipofuscin in the retinal pigment epithelium (RPE) as imaged by autofluorescence. However, present acquisition systems provide only relative AF levels, not the biologically critical levels of lipofuscin itself. We have assembled a team that includes the world authority on autofluorescence imaging, Francois Delori, complementary expertise in ophthalmic instrumentation, retinal disease and imaging, retinal biology and biomedical engineering to create and systematically exploit instrumentation for absolute AF measurements and in vivo true lipofuscin levels to advance our understanding of RDD well beyond its present level. The system, a specially modified confocal scanning laser ophthalmoscope (cSLO) harnessed to our cutting edge biomedical image analysis techniques, will create a paradigm shift in the research of AMD, STGD and RP by quantifying the fluorescence associated with RDD lesions in patients. Further, we will make and use similar instrumentation to study animal models. Thus mice, the most widely used animal models for RDD, will no longer have to be sacrificed for lipofuscin levels, which offers the scientific advantage of multiple measurements from individual mice over time as well as the obvious humanitarian benefit. Autofluorescence lesions are keys to answering long-unresolved questions about the role of lipofuscin in AMD, STGD and RP. Absolute autofluorescence imaging, uniquely clinically attainable with the proposed device, offers a vision of in vivo, quantitative two dimensional lipofuscin measurements. In cohorts of these patients, we will thus perform prospective analysis of these images, acquired simultaneously with high resolution spectral domain optical coherence tomography images of retinal structure from the same device, to answer such questions as: is lipofuscin a primary cause of or does it result from retinal damage? By further registering these scans with photographic and infrared image modalities, and correlating them with genotype and functional tests such as microperimetry, we will build a powerful data structure from which will flow a host of new disease models and hypotheses to test in RDD. Retinal degenerative disease takes a terrible toll on our population, both young and old. This new technology will ultimately provide a firmer basis for monitoring patient progress and response to new therapies, including gene therapy.
Absolute autofluorescence imaging with a specially modified confocal scanning laser ophthalmoscope will provide, for the first time, in vivo measurements of fluorophores in retinal degenerative disease (RDD), including age-related macular degeneration. Identification of these signature compounds will be uniquely instrumental in understanding RDD, the leading cause of blindness in our country, with the insights so obtained of high value in clinical care of RDD patients, saving sight for our patients, and enormously benefiting our society.
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