The power is out and the room is completely dark

Why

Meera has noticed something true: step from bright sun into a dim room and it does slowly become visible, so 'eyes adjust' is real. But adjusting means the pupil opening wider to gather what little light is there; the eye cannot manufacture light that does not exist. Seeing is light leaving an object, travelling to your eye, and landing at the back of it. In a truly sealed dark room nothing bounces off anything to reach your eye, no matter how wide the pupil opens or how long you wait. Even a cat, famous for night vision, needs a trace of light; a cat in a sealed cellar is as blind as you. Test: the instant a phone screen or a crack under the door lets light in, the room appears. Kabir is right: no light, no sight, because the eye is a receiver, not a source.