For closed angle glaucoma the laser light can be used to create small holes in the iris to release the pressure in the posterior chamber causing the iris to be pressed in the chamber angle closing the outflow for the intraocular fluid. The result is an equalization of the pressure between posterior and anterior chamber, which leads to a draw back of the iris opening the chamber angle again.

• ALT (Argon laser trabeculoplasty)

For open angle glaucoma the laser light is directed into the chamber angle to achieve lowering of the intraocular pressure inside the eye. In the chamber angel, the light is directed to the trabecular meshwork to change the structure of the tissue by the coagulative effect. Coagulation of the collagen layers in the meshwork causes stress to the tissue which reduces the resistance to the outflow path of the intraocular fluid passing through the meshwork and leaving the eye via Schlemm’s Canal.

The second effect is that the heat and its adverse effect on the tissue components lead to a biological initiation of ligands, which are released by meshwork endothelial cells. These ligands are capable of lowering the resistance in the barrier from the trabecular meshwork to the Canal of Schlemm. This leads to a reduction in intraocular pressure.