Glaucoma typically has no symptoms until its late stages, at which point peripheral vision is damaged, and eventually central vision can be affected.

“it has no symptoms until the very end so and what happens is that your peripheral vision is damaged and most people will not detect a a slight reduction in their peripheral vision particularly if it's segmental there's just one little area off to the side that they're that they can't see particularly if the other eye is covering for that area but as glaucoma progresses it can affect central vision and then it becomes symptomatic”