This is a prospective, randomised, controlled study. Patients will be selected for this study who require bilateral laser trabeculoplasty for IOP control. Eyes will undergo a medication wash-out 4 weeks prior to the baseline study session (S1). There will be a security visit at 2 weeks to make sure that the IOPs remain within a safe range. Following S1 both study eyes will receive laser treatment, as assigned by randomization, within a period of 2 weeks. Eyes will be randomized to receive the SLT (SLT eye) or PLT (PLT eye) treatment. Both laser procedures will be performed in one session (for 360° of the angle), if patients tolerate it. Otherwise, they will be split into two sessions (each treating 180° of the angle) to be performed within 1 week of each other. The same pre- and post-laser procedures will be applied on both eyes.