Equipping this lets you disregard darkness completely! If you're not in a world you own, they consume 1 D Battery for every minute you wear them. You can wear them without a battery if you just want to look cool, though.
Scared of the dark? We have a solution. You can wear these goggles just to look cool, but if you also happen to have a D Battery (batteries not included) on you, you will able to see through darkness like it's not even there! Each D Battery can power your goggles for 1 minute. If you are in a world you own, the goggles will not require batteries! Note: you can't turn the goggles off without removing them, so you'll be wasting your battery if you wear them in daylight while carrying D Batteries.
When worn in the player's own world, all Dark Cave Background or similar "dark" backgrounds turn visible (they no longer apply darkness on blocks). When worn in somebody else's world, it will have the same effect, except it will use up a D Battery for every minute the player has the Night Vision Goggles equipped. If the player has no D Battery in their inventory and the player is in somebody else's world, the goggles will stop working.