YAG is an abbreviation for neodymium yttrium-aluminum-garnet, the material used generate a short pulsed, high-energy light beam in the infra red wavelength of 1064 nm. The YAG laser is a surgical instrument that can be precisely focused by computer to cut, photovaporize, or fragment tissue. The YAG laser is used to treat posterior capsular opacification; a clouding of the remaining capsular tissue that develops postoperatively in as many as 75% of cataract removal operations. The tissue is vaporized with carefully controlled pulses of the YAG laser, and the surgery is performed on an outpatient basis. The common misconception that "lasers" are used to remove cataracts occurs because post-cataract patients eventually require YAG laser capsulotomy. Z