Whichever type of laser is used, this procedure creates a permanent passage for the aqueous humor to flow through from the posterior to the anterior chamber. Indeed, the hole helps the aqueous fluid flow from one side of the iris to the other.
The procedure also pushes the iris tissue backward, opening the angle in the majority of cases. It effectively exposes the trabecular meshwork (or internal drainage system of the eye) so that fluid outflow is enhanced.