The aim of this clinical trial is to investigate whether oral semaglutide can be used to treat open-angle glaucoma. The main question it aims to answer is: Does oral semaglutide safely improve inner retinal function in patients with open-angle glaucoma as measured by the photopic negative response of the electroretinogram.
Researchers will compare oral semaglutide to a placebo (a look-alike substance that contains no drug).
Participants will:
* Take semaglutide or a placebo every day for 6 months.
* Visit the clinic 5 times in total for tests and interviews: At baseline (the first day they are included in the study), after 1 month, after 2 months, after 3 months, and after 6 months (the last day they are included in the study).