Laser Peripheral Iridotomy (LPI) is type of laser procedure used in closed-angle glaucoma. It is used to equalize the pressure between the front and back chambers of the eye. This is done by using a laser to create a very small hole(s) in the iris to allow the fluid to drain from the back to the front of the eye where it can be drained through the trabecular meshwork. The LPI can be done prophylactically (preventively), or on an emergent basis if there is a sudden increase in eye pressure.