In physiological terms, ALT has been shown to lower the IOP primarily by increasing the conventional outflow facility7. There are two putative mechanisms by which this may be facilitated8. Thermal coagulation and shrinkage by ALT may mechanically open up the adjacent trabecular meshwork and Schlemm's canal. Alternatively the delivery of laser energy may trigger biological processes and activation of matrix metalloproteinases in the microenvironment of trabecular meshwork that lead to a remodeling of tissues resulting in improved outflow facility. ALT uses argon or another thermal laser to photocoagulate tissues around the trabecular meshwork. The settings vary depending on the tissue response and pigmentation. Most clinicians use 600-1500mW, 50-100 spots, 50 micron spot size and 0.1 sec duration.