Advancing age predisposes us to a number of neurodegenerative diseases, yet the underlying mechanisms are poorly understood. With some 70 million individuals affected, glaucoma is the world's leading cause of irreversible blindness. Glaucoma is characterized by the selective loss of retinal ganglion cells that convey visual messages from the photoreceptive retina to the brain. Age is a major risk factor for glaucoma, with disease incidence increasing near exponentially with increasing age. Treatments that specifically target retinal ganglion cells or the effects of aging on glaucoma susceptibility are currently lacking.
Despite considerable advances in retinal prostheses over the last two decades, the resolution of restored vision has remained severely limited, well below the 20/200 acuity threshold of blindness. Towards drastic improvements in spatial resolution, we present a scalable architecture for retinal prostheses in which each stimulation electrode is directly activated by incident light and powered by a common voltage pulse transferred over a single wireless inductive link.
You are free to share this article under the Attribution 4.0 International license. A form of artificial intelligence designed to interpret a combination of retinal images successfully identified a group of patients known to have Alzheimer's disease, researchers report. The findings suggest the approach could one day be used as a predictive tool, according to the new study. The novel computer software looks at retinal structure and blood vessels on images of the inside of the eye that have been correlated with cognitive changes. The findings provide proof-of-concept that machine learning analysis of certain types of retinal images has the potential to offer a non-invasive way to detect Alzheimer's disease in symptomatic individuals.
Early experiments are promising, although they do reveal some limits. Rats with the implants don't show any improvement over their afflicted peers in low light (since the light-sensitive material isn't kicking in), but their response to brighter light is nearly as good as that of a healthy animal. And since the materials are organic-friendly, the rats kept the implants in place for 6 months with no inflamed tissue. Don't get too excited by the discovery. The scientists aren't entirely clear how the electrical charges turn into nerve responses, for one thing.
We found that human organoids and retinas have similar distributions, gene expression profiles, and morphologies of cone subtypes. During development, S cones are specified first, followed by L/M cones. This temporal switch from specification of S cones to generation of L/M cones is controlled by thyroid hormone (TH) signaling. In retinal organoids that lacked thyroid hormone receptor β (Thrβ), all cones developed into the S subtype. Thrβ binds with high affinity to triiodothyronine (T3), the more active form of TH, to regulate gene expression.