What are the ways to cure glaucoma at 80?

Readily treated. Glaucoma is mostly a problem with outflow of the internal (aqueoius) circulation of fluid inside the eye. To overcome the resistance of the outflow, the pressure elevates. This can damage the back of the eye and lead to vision loss. Treatment is by medication lowering fluid production, laser enhancement of outflow or surgical drainage procedures. No actual cure since the cause is unknown.
No cure. Unfortunately we cannot cure glaucoma. However, we are very good at slowing the disease down so much that it does not impair your quality of life. See your doctor for the various treatment options.