Final answer:
A tumor in the right visual cortex affects the left visual field of both eyes, while a tumor compressing the right optic nerve affects the visual field in the right eye only.
Step-by-step explanation:
The visual field that would be affected by a tumor in the right visual cortex would be the left visual field of both eyes. This is because the right cortex processes information from the left visual field due to the way the optic pathways are structured. A tumor compressing the right optic nerve would affect the vision in the right eye, causing a loss of the entire visual field on that side (right anopsia).
When considering a tumor compressing the right optic nerve, it will affect the visual field of the right eye because the damage is before the optic chiasm, where the nerve fibers cross. If there is a tumor in the right visual cortex, the left visual field in both eyes is lost (left homonymous hemianopia) because the tumor would affect the processing of visual information on the contralateral side of where the visual information originates.