My dad lost one eye to retinal cancer at age 50-ish. It didn’t slow him down hardly at all. He still drove fine. In fact, after a suitable recover period, the FAA let him go back to work flying 747s, which he did for another 10 years with one eye. You can live a very normal life with one eye.
He did give up motorcycle riding because he was concerned that if he got anything in his good eye, he’d be unable to see to stop the bike. Behind a windshield in a car he was OK, but he wasn’t going to risk getting a bug or some grit blown in under his helmet’s faceshield. I bet he had a couple close calls before he came to that conclusion though.
FYI, the binocular-vision-for-depth-perception thing works out to about 15 feet. After that, human depth perception is almost entirely a function of object clarity, foreground-occludes-background & other essentially monocular visual processing functions.
The loss of visual field is far more of an issue for day to day activities. He found that by pointing his head 10-20 degrees to the blind side he got essentially the same useful field of view as normal. He did have to be careful about deliberately looking over his shoulder, which was a strain to twist that far on the blind side.
The loss of depth binocular depth perception IS significant at close ranges. He spilled a lot of water refilling glasses which were a couple inches away from where he thought they were. But he learned little workarounds for that, like grasping the glass with the other hand. Some adaption to lousy close-in depth perception is needed, but overall it’s not a big deal.
Now the downside.
His tumor was malignant & he/they left the eyeball in place after they irradiated it to kill the tumor, which also killed the optic nerve & the vision. The eye looked OK, it just didn’t work anymore. At the time that was standard practice. The glass eyes weren’t as trouble free as all that, and the eye’s enough of a self-contained system that the medical opinion was there was not much to be gained by pulling the eye out & installing a prothesis.
15 years later a small chunk of that tumor metastized to his guts & killed him over the course of a year or two.
Moral of the story: don’t take chances with a malignant mass anywhere in the body. Overreaction is barely enough. Benign is a different matter, provided the diagnosis is certain.
My advice based on my vicarious experience: Do the appropriate thing for the cancer treatment, whatever that may be, but err on the side of caution. Don’t sweat the mono vision thing. It’s a minor pain in the ass every day, but not much more than that. Don’t let yuor concern over vision loss turn into a way to rationalize less-than-agressive medical intervention when it’s needed.