In this study, Hyaluronan Thiomer i.o. will be implanted during a combined surgery of cataract and non - penetrating deep sclerectomy in a group of 16 patients with primary open angle glaucoma and clinically significant cataract. Given that a considerable number of glaucoma patients also suffer from cataract, it is reasonable to test Hyaluronan Thiomer i.o. during a combined procedure of phacoemulsification and deep sclerectomy. This is also of importance because a combined procedure avoids the need of a second operation in this group of patients. Finally, it has been shown that combined phacoemulsification - deep sclerectomy does not induce a further risk compared to deep sclerectomy alone(open phase I study).