Researchers from the National Eye Institute have discovered that the retinal lesions caused by vitelliform macular dystrophy (VMD) differ depending on the type of gene mutation. The research is published in Investigative Ophthalmology & Visual Science.
Addressing these differences may be key in designing effective treatments for this and other rare diseases. NEI is part of the National Institutes of Health.
"The NEI's long-term investment in imaging technology is changing our understanding of eye diseases," said NEI Director Michael F. Chiang, M.D. "This study is just one example of how improved imaging can reveal subtle details about pathology in a rare eye disease that can inform the development of therapeutics."
VMD is an inherited genetic condition that gradually impairs vision by causing the light-sensing retina to degenerate. VMD has been linked to the genes BEST1, PRPH2, IMPG1, and IMPG2. Age of onset and severity vary greatly depending on the gene and mutation.
A lesion in the central retina (macula) that resembles an egg yolk and is a buildup of toxic fatty material called lipofuscin is a feature shared by all forms of the disease. 1 in 5,500 Americans suffer from VMD, which has no known cure at this time.
At the NIH Clinical Center, patients with VMD had their retinas examined using multimodal imaging by Johnny Tam, Ph.D., chief of the NEI Clinical and Translational Imaging Unit. Adaptive optics, a technology that uses flexible mirrors to improve resolution, is used by Tam's multimodal imaging to examine live cells in the retina in unprecedented detail, including the light-sensing photoreceptors, retinal pigment epithelial (RPE) cells, and blood vessels.
Tam and his team worked with doctors at the NEI Eye Clinic to use genetic testing and other clinical evaluations to characterize11 participants. After that, multimodal imaging was used to assess the participants' retinas.
Assessment of cell densities (photoreceptors and RPE cells) near VMD lesions revealed differences in cell density according to the various mutations. Photoreceptor cell density was more impacted by IMPG1 and IMPG2 mutations than RPE cell density.
The opposite was accurate for BEST1 and PRPH2 mutations. The researchers found similar impacts on cell density in the unaffected eye in participants who only had one afflicted eye, despite the absence of lesions.
Tam is utilizing multimodal imaging to study both more prevalent and less common retinal diseases, such as age-related macular degeneration.