Fluid is constantly produced inside the eye, and it has to go somewhere. For that, there's a thin channel, like a drainpipe. With age, the pipe narrows, but in most people the pressure inside the eye stays normal. Why? Because helper cells, macrophages, gather around the pipe. They release the protein VEGFA, which strengthens the channel walls and helps fluid drain away.
Scientists tested this in mice. When the Vegfa gene was removed from macrophages, eye pressure rose and outflow got worse. So the helpers really are needed. But they have a commander: the protein TIE2. If there's too little of it, the channel narrows more, and pressure rises even at a young age. So the scientists gave the mice gene therapy that boosts TIE2. Outflow improved, pressure dropped, and the retina's nerve cells survived better.
Glaucoma used to be treated only as a clogged pipe: drops, surgery. Now it's clear we can support the helpers themselves. If we boost the TIE2 signal in older people, we might protect vision for a long time without daily drops. The pipe ages, but the repair crew doesn't leave.
The area of Schlemm's canal in mice decreases with age by about 14%, comparable to the loss of aortic cross-sectional area in aging humans.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.