Going off of what this electron microscope manufacturer says on their website you can read a CD using an optical microscope and you can almost read a DVD.
The limit is apparently somewhere around 500nm and a DVD would need 400nm. So with a bit of optical enhancements it should be possible.
And if you have the ability to put a microscope and a camera into an almost perfect vacuum you probably can go even further (at least considering what e.g. ASML says for lithography with EUV)