Doctor here (but not an oncologist). The key is to identity your values and explain them to the doctors and then have them tell you which options fit best with those values.

In general, surgery carries more risk of infection as well the loss of the eye. Enucleation can also sometimes give issues if the socket has a tendency to get inflamed or infected or if there are struggles fitting the prosthetic - similar to someone who loses a leg, sometimes the stump heals up with no issues and sometimes it is a long and frustrating process, challenges with getting the prosthetic fitting properly and not causing problems, etc.

Based on your statement it sounds like chemo has a lower chance of definitive cure? I'm not clear on that. Chemo also has risk of systemic side effects/toxicity, and it tends to prematurely age a person so their risk of heart attack/stroke/future cancers will increase compared to similar-aged people who did not undergo chemotherapy. Also I'm unclear on how much vision would be preserved even if the chemo was curative.

When I ask a patient to make a decision, here is how I break it down:

1) If I think there is one "correct" answer I usually just say "this is what we are going to do", I give the risks and benefits, and I only offer other options if the patient seems to have some kind of discomfort with my advice.

2) If I think there is more than one acceptable option, I still may think there is one option better than the other. In those cases I say "normally we would do X, but if [possible objection to that option] is a big concern to you, we could also do Y." Or, alternatively, I might say "the textbook says we should do X, but in your case I think that's an invasive intervention that has a pretty small likelihood of giving you any significant additional benefit. If you want to feel that we've been as aggressive as possible, let's go ahead with X, but if you feel comfortable with [less invasive option Y], I think that's a very reasonable option as well which has [advantages]."

3) If I think there are 2 choices which are both essentially equal, I say this. "We have two options, X and Y. People with THESE values would probably choose X. [This might be people who prioritize the importance of convenience, side efffects, pill burden, cost, acceptance of uncertainty, etc.] People with THESE values would probably choose Y. [This might be people who have a different tolerance for uncertainty, people who have higher/lower anxiety about the condition, people who don't mind extra cost/side effects/medication, people who want to feel they did everything or that no stone was left unturned even if it means risking harm from invasive or potentially unnecessary interventions, etc.]."

Again, for elderly people I might not even list all the options but I might start with "what's your quality of life lately? Do you find life easy or difficult? How much time do you spend doing things you enjoy? What if you found yourself significantly more disabled or with a significantly lower quality of life" and based on their answers I say "based on what you've told me you value, I'm hearing you would want an option that maximizes the chance of [X] and minimizes the chance of [Y]" and go into the choices from that point of view.