Final answer:
Glaucoma primarily affects peripheral vision, leading to progressive vision loss and potentially leaving only central vision intact, similar to tunnel vision.
Step-by-step explanation:
While macular degeneration affects central vision, resulting in a black spot in the center of one's visual field and a loss of detailed vision due to the death of cells in the macula, glaucoma primarily affects peripheral vision or the outermost areas of the field of vision. In glaucoma, the optic nerve is damaged, usually due to high intraocular pressure, leading to progressive vision loss starting with the periphery. This can eventually lead to tunnel vision, where only the central visual field remains. Conditions like bilateral hemianopia, resulting from a pituitary gland growth pressing against the optic chiasm, could also cause loss of lateral peripheral vision without the loss of superior and inferior peripheral fields.