Isn't the display-to-retina capture handled by physical security? Ie -- aren't most top-secret (not sure the exact classification but you know what I mean) facilities controlled in regards to what electronic equipment you can take inside?
Yes, good point. But it all depends on level of risk, type and amount of data etc.
You don't need any electronics for a film camera. Or any metal, for that matter. It's a risk to take such an item in, but maybe it's worth it for your use case.
And I guess if it's small amounts of text, there's always human memory (or writing on your skin?).
So you are (obviously I guess) trusting the people accessing the data to not abuse it, "helping" that trust with whatever technical countermeasures make it harder to move bulk data.
