Laser Eye

The Laser Eye, also known as an Eye Beam, is an eye that appears in the walls of certain dungeons of A Link to the Past. Laser Eyes are found in Misery Mire, Turtle Rock and Ganon's Tower. They remain static, but when Link passes infront of them, they will start pelting him with laser beams, similar to a Beamos. Unlike Beamos in this game, the beams are rapid, but can be blocked by using the Mirror Shield. The Mirror Shield is usually needed to progress through the Turtle Rock dungeon unless the player can find another way past the beams. Their precise behavior varies, with some partially closed eyes only opening and firing upon Link if he faces their direction, otherwise they will remain shut. These particular eyes will often sit above doorways which will also vanish when the eye opens, meaning that Link can only leave these rooms by moving backwards through the door (done by holding out his sword as if to charge it for a Whirling Blade Attack).

Trivia

 * Moving with your back to an enemy was later used Link's Awakening with the Mask-Mimics.
 * A similar trap called the Fire Eye later appears in Ocarina of Time.
 * The Japanese name for the Laser Eye includes the word "karan", Japanese onomatopoeia for something rattling or opening.