Authors: Naamah Maundrell
Researchers from the University of Rochester Medical Center (NY, USA) have developed a new technique that is able to non-invasively image the retina at a previously unattained resolution. The study, published in the Proceedings of the National Academy of Sciences, describes how the new method can distinguish individual retinal ganglion cells (RGCs), which could be of huge benefit in the early diagnosis of diseases such as glaucoma.
The new technique, termed multi-offset detection, modified the existing technology – confocal adaptive optics scanning light ophthalmoscopy. The new method involved combining multiple images in which the size and location of the detector, utilized to gather light scattered out of the retina, had been varied.
Scientists led by David Williams (University of Rochester) performed the new technique on animals, individuals with normal vision and those with age-related macular degeneration. Individual RGCs could be identified and, specifically in animals, detailed structures within the cells – including the nucleus – were distinguished.
If this high resolution could be achieved in human cells, the new technique could be utilized to assess glaucoma, which is currently diagnosed by analyzing projecting nerve fiber thickness rather than the RGCs themselves due to their high transparency. “In principle, this new approach might eventually allow us to detect the loss of single ganglion cells. The sooner we can catch the loss, the better our chances of halting disease and preventing vision loss,” commented Williams.
Cone photoreceptors were also imaged using the new technique. Scientist Ethan Rossi (University of Pittsburgh School of Medicine, PA, USA) explained: “This technique offers the opportunity to evaluate many cell classes that have previously remained inaccessible to imaging in the living eye…not only RGCs, but potentially other translucent cell classes and cellular structures.”
In the future, Rossi plans to continue working with Williams to replicate these studies in a large number of participants. Additionally, further research will aim to improve the robustness of the technique before it can be used in a clinical setting.
Sources: Rossi EA, Granger CE, Sharma R et al. Imaging individual neurons in the retinal ganglion cell layer of the living eye. PNAS. doi:10.1073/pnas.1613445114 (2016) (Epub ahead of print); www.urmc.rochester.edu/news/story/4694/a-closer-look-at-the-eye.aspx