Background: Selective laser trabeculoplasty SLT is a new method to reduce intraocular pressure in eyes with primary open angle glaucoma. With a Q-switched, frequency-doubled Nd:YAG laser it targets the pigmented trabecular meshwork cells without visible damage to the adjacent non-pigmented tissue. SLT acts non-thermally, the intracellular microdisruptions triggered by the laser are confined to the targeted cells, the laser pulses are so short that heat created within the targeted cells does not have time to spread to the surrounding tissue. A clinical prospective study was conducted to evaluate the longterm results, safety and efficacy of SLT in the treatment of open angle glaucoma. Patients and Methods: Since 2002, we have performed a selective laser trabeculoplasty in 269 eyes: in 17 eyes with ocular hypertension, in 239 eyes with primary open angle glaucoma, in 11 eyes with low tension glaucoma, while 2 eyes had a secondary glaucoma due to uveitis. In 22 eyes the primary initial treatment was SLT. Results: Three months after treatment, the mean IOPreduction from baseline was 3.4 mm Hg, respectively 15%, after 12 months the mean IOPreduction was 3.0 mmHg (12.9%), and after 24 months 2.7 mmHg or 12.1%. The response curve of the eyeswith ocular hypertension greatly resembled the eyes with primary open angle glaucoma and with low tension glaucoma. Conclusions: SLT has shown reasonable efficacy in lowering IOPin eyes with primary open angle glaucoma and ocular hypertension, both as a first-line treatment and as a treatment in medication-refractory eyes. SLT is effective for patients who have had prior treatment with ALT. Long-term follow-up studies are needed to determine whether the IOPlowering effect is sustained over time, and to assess the efficacy of repeated SLT. The exact biological effect induced with the SLT is still not understood. Background: Selective laser trabeculoplasty SLT is a new method to reduce intraocular pressure in eyes with primary open angle glaucoma. With a Q-switched, frequency-doubled Nd: YAG laser it targets the pigmented trabecular meshwork cells without visible damage to the adjacent non- pigmented tissue. SLT acts non-thermally, the intracellular microdisruptions triggered by the laser are confined to the targeted cells, the laser pulses are so short that heat created within the targeted cells does not have time to spread to the surrounding tissue. A clinical prospective patients and Methods: Since 2002, we have performed a selective laser trabeculoplasty in 269 eyes: in 17 eyes with ocular hypertension, in 239 eyes with primary open angle glaucoma, in 11 eyes with low tension glaucoma, while 2 eyes had a secondary glaucoma due to uveitis. In 22 eyes the primary initial tre atment was SLT. Results: Three months after treatment, the mean IOP reduction from baseline was 3.4 mm Hg, respectively 15%, after 12 months the mean IOP reduction was 3.0 mmHg (12.9%), and after 24 months 2.7 mmHg or 12.1%. response curve of the eyes with ocular hypertension great resembled the eyes with primary open angle glaucoma and with low tension glaucoma. Conclusions: SLT has shown reasonable efficacy in lowering IOPin eyes with primary open angle glaucoma and ocular hypertension, both as a first-line treatment and as a treatment in refractory eyes. SLT is effective for patients who have had prior treatment with ALT. Long-term follow-up studies are needed to determine whether IOP effect is sustained over time, and to assess the efficacy of repeated SLT The exact biological effect induced with the SLT is still not understood.