I just don’t know, and I’m hoping that someone with specifical medical knowledge will chime in. I don’t think that they took out the lens entirely and relied on eyeglasses to focus light, because according to the Wiki article cataract surgery has been done for millennia, but ground glass lenses date back only to, what, the eighteenth century? It wouldn’t have made sense to do a surgery, with all the risk of infection, just to turn bad vision into useless vision.
I don’t think there is anything extraordinary about seeing this 410 nm line. In a proper environment I would bet most people can see it. My guess is people don’t see it because they aren’t in a completely dark environment. In my experience, it is difficult to see, but most of my students and myself could see it with shoebox spectrometers.