>the screen is two-way?
No. But LEDs can sometimes be used to measure the level of light they're exposed to if they happen to be connected to a suitable microcontroller correctly. And if this level is correlated to a know shifting light source then, in some cases, it theoretically act as a kind of single pixel camera that could slowly build up an image of a scene..
I meant that very, very tongue-in-cheek. It's not a real danger. But..
The backlight in a LCD monitor wouldn't work. But any little blinky-light indicator LED is capable of functioning as a (inefficient) photodiode. So if a micro can reverse-bias an LED (charging it up like a tiny capacitor), switch to a high-impedance input state, and measure the time it takes to sense the shift from a 1 to a 0 then it can measure the intensity of light falling on it via the photoelectric effect. Combine that with light from another source moving across the room (light from cars driving by at night, light from TVs/monitors, etc) and something like this technique…
https://www.technologyreview.com/s/510411/first-3-d-images-created-with-single-pixel-sensor/
…and you theoretically have a single pixel camera.
Don't worry. This is a long way from practical.