Researchers at the National Eye Institute in the U.S. have developed a retinal imaging technique that reveals live neurons, blood vessels, and epithelial cells within the retina. The method involves combining adaptive optics and angiography, and allows the researchers to view complex units of cells that interact in the outer edge of the retina. As this retinal region is involved in a range of diseases, including atherosclerosis, age-related macular degeneration (AMD), and Alzheimer’s disease, the researchers hope that the technique could help with diagnosis and disease monitoring.
“For studying diseases, there’s no substitute for watching live cells interact,” said Johnny Tam, a researcher involved in the study. “However, conventional technologies are limited in their ability to show such detail.”
Post-mortem tissue samples and tissue biopsies are frequently used to study cellular characteristics in disease. However, such samples provide only a rough approximation of living tissue and make it difficult to monitor disease progression over time. A non-invasive method to accurately monitor living cells in the retina has not been available, partly because light becomes distorted as it passes through the eye.
To help overcome this issue, the researchers employed adaptive optics, a technique which is used in space telescopes, and which involves deformable mirrors and computer algorithms to correct for light distortion. The researchers combined this optical technique with angiography, which involves injecting a dye into the blood, and then using a camera to image the blood vessels within the retina.
The new technique resulted in high-resolution images of the retina that allowed the researchers to observe features in real time that had never been seen before in living retinal tissue, including complex units of epithelial cells, photoreceptors, and capillaries.
The approach has potential in helping to diagnose and understand a variety of diseases. The research team tested the imaging technique in a patient with retinitis pigmentosa, and discovered that the photoreceptors had died in specific regions of the retina, but that retinal pigment epithelial cells (RPE cells) and capillaries were still intact in these regions.
“In the past, we have not been able to reliably assess the status of photoreceptors alongside RPE cells and choriocapillaris in the eye,” said Tam. “Revealing which tissue layers are affected in different stages of diseases – neurons, epithelial cells, or blood vessels – is a critical first step for developing and evaluating targeted treatments for disease.”
Top image: Photoreceptors (left), retinal pigment epithelial cells (center), and choriocapillaris in the living human eye.
Study in Communications Biology: Combining multimodal adaptive optics imaging and angiography improves visualization of human eyes with cellular-level resolution…
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