The vitreous is the jelly-like stuff in your eyeball. It does not detach, although it can leak out. Retinas detatch and you will see flashes of white light when it does. Your ophthalmologist will know what to do in your particular case. It might be temporary or it might be something that requires some intervention.

I would not treat this casually. Get a second opinion if you are not happy with the first. And I would certainly like to know why it detached--injury, diabetes, multifocal choroiditis, macular degeneration?

As someone who has lost all retina in one eye, I can tell you that it causes problems. You only have 2 eyes. I'm down to just one, and that doesn't leave much wiggle room.