After undergoing cataract surgery, patients regain clear vision. Some patients might have a decline in vision a few weeks after going cataract surgery due to something we call a secondary cataract. A secondary cataract is not actually a cataract, it is caused from the capsular bag turning cloudy. A YAG laser is a special type of laser that may be used to treat a secondary cataract, which is the clouding of a membrane that sometimes occurs after cataract surgery. The procedure is fast and effective is covered by most insurance plans.