This is a prospective non-randomised interventional study to assess the efficacy and safety of the Glaukos GTS-400 iStent combined with cataract surgery. The patients enrolled in the study had cataract and primary open angle glaucoma, pseudoexfoliation glaucoma or ocular hypertension. A total of twenty patients were enrolled in the study, with an average age of 75.1±8.6 years. After the phacoemulsification and intraocular lens (IOL) placement, two GTS-400 iStents were implanted through the clear corneal incision (~2.85mm) placed for phacoemulsification. A Swan-Jacob gonioscope was used for the insertion at the nasal part of the trabecular meshwork. Post-operative visits were scheduled for one day, one week, three months, six months and one year. Three patients received one iStent for logistic reasons. The mean IOP with medication was 19.95±3.71mmHg and after washout of anti-glaucoma drops was 26±3.11mmHg. At the end of follow-up the mean IOP was 16.75±2.24mmHg, determining a final IOP reduction of 35.68% (p<0.001). At baseline, the mean number of glaucoma medications was 1.3, with a range of zero to two medications. At the final visit, the mean number of medications use had fallen to 0.3 (p<0.001). Fifteen subjects (75%) required no ocular hypertensive medication. One year after surgery, complete success was achieved in 10 of the patients (50%), while relative success was recorded in 19 of 20 patients (85%). Complete success was defined as IOP reduction to <18mmHg without medication; relative success was defined as IOP reduction to <18mmHg with medication or to <21mmHg without medication. Transient IOP elevation to above 30mmHg was observed in three eyes one day post-operatively, probably due to the persistence of viscoelastic. By the one week visit this transient IOP elevation had resolved in all three eyes. The authors concluded that combined cataract surgery with GTS-400 iStent implantation seems to be an effective and safe procedure.