What are the symptoms of optic atrophy in glaucoma?

Decreased vision: Atrophy of the optic nerve implies that there is loss of tissue (ganglion cell axons) and correspondingly loss of function. Technically it's a neuropathy and the causes are any disease that affects the ganglion cell axons from the eye to the lateral geniculate nucleus in the brain. In glaucoma it's believed to the result of too high or unstable IOP which damages axons causing vision loss.

Glaucoma is sneaky!: Glaucomatous optic atrophy typically has very little to no symptoms until very late in the course of the disease. This is why many patient don't take glaucoma seriously until the vision worsens, then it is too late. Late symptoms would be poor or dim vision. Poor night vision.