One of the most harmful components of degenerative eye diseases (such as glaucoma, macular degeneration), are the irreversible death of cells in varying locations of the eye. These cells, which have functions that range from capturing light to sending visual information from the brain, cause vision loss or permanent blindness when they are killed. Researchers have tried to regenerate these cells by varying methods, but have been largely unsuccessful until recently. A team at the University of Wisconsin led by Dr. David Gamm grew retinal organoids, leading to varying eye cell types to develop. They then cultured the cells along with a tracer to track whether it could form synaptic connections using the rabies virus, because that specific virus travels from nerve cell to nerve cell using synaptic connections. The team discovered that the cells they had grown were able to form synaptic connections, indicating significant implications for the development of eye-based artificial cell growth. You can read more here:
https://www.nih.gov/news-events/nih-research-matters/lab-grown-eye-cells-form-new-neural-connections