My 92 year old mom has been diagnosed several years ago with closed angle glaucoma which she never had treated, is is safe for her to take valium or would that put her vision at risk?

Valium is formally contraindicated in glaucoma due to its potential of increasing intraocular pressure. Best to clarify in actual context would be your mother's prescriber who should be aware of her diagnosis of glaucoma.

Closed or narrow angle glaucoma has to do with pressure evelavtions caused by narrowing or closing of the outflow tract for fluid exiting the eye. It is serious and can cause severe pain and blindness. It is usually easily treated with a painless in-office laser procedure. Vallium is not an issue. She should have the laser procedure.