Using a new imaging technique, researchers at the National Eye Institute have determined that retinal lesions due to biliary macular dystrophy (VMD) vary depending on the gene mutation. Addressing these differences may be key to developing effective treatments for this and other rare diseases. NEI is part of the National Institutes of Health.
“NEI’s long-term investment in imaging technology is transforming our understanding of eye disease,” said NEI Director Michael F. Chang, MD. “This study is just one example of how improved imaging can reveal fine details of the pathology of a rare eye disease that can inform the development of therapeutics.”
AMD is an inherited genetic disorder that causes progressive vision loss through degeneration of the light-sensitive retina. Genes associated with VMD include BEST1, PRPH2, IMPG1, and IMPG2. Depending on the gene and mutation, age of onset and severity vary widely. All forms of the disease have in common a lesion in the central part of the retina (the macula), which looks like an egg yolk and is an accumulation of a toxic fatty material called lipofuscin. AMD affects about 1 in 5,500 Americans, and there is currently no cure for the condition.
Johnny Tam, Ph.D., chief of NEI’s Division of Clinical and Translational Imaging, used multimodality imaging to evaluate the retinas of AMD patients at the NIH Clinical Center. Tema’s multimodal imaging uses adaptive optics—a technique that uses deformed mirrors to improve resolution—to view living retinal cells, including light-sensitive photoreceptors, retinal pigment epithelium (RPE) cells, and blood vessels in unprecedented detail.
Tam and his team worked with clinicians at the NEI Eye Clinic to characterize the 11 participants through genetic testing and other clinical assessments, then evaluated their retinas using multimodality imaging. Assessment of cell density (photoreceptor and RPE cells) near VMD lesions revealed differences in cell density depending on the different mutations. IMPG1 and IMPG2 mutations had a greater effect on photoreceptor cell density than RPE cell density. The opposite was true for PRPH2 and BEST1 mutations. In participants with only one affected eye, the researchers noted similar effects on cell density in the unaffected eye, despite the absence of lesions.
Tam uses multimodal imaging for a variety of other rare and more common retinal diseases, including age-related macular degeneration.
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