I don't have any answers for you, but did want to ask: did they do a thorough eye exam on you, checking for macular degeneration? While yes, drusen can occur with some chemotherapies, it can also be a significant symptom of developing macular degeneration. While not as immediately threatening as the risk of a detached retina, it still is a debilitating eye condition that can be treated to some extent if detected early enough. If you haven't had a very thorough eye exam since the development of these drusen, perhaps you should make an appt with a good opthamalogist.
I wish you the very best.
Tre