A trabeculectomy is a surgical procedure in which an external opening is created to the anterior chamber of the eye. This needs to be performed in a hospital setting under a microscope. A partial thickness incision is made through the white of the eye, which gets stitched closed again to form a slow-leaking, trap-door-like opening. This is covered by the conjunctiva (mucus membrane of the eye) and leads to the formation of a small blister on the eye known as a bleb.
The trabeculectomy has a long-standing history as a glaucoma procedure, with good outcomes for the management of intraocular pressure. The unpredictability of the healing after surgery, together with long-term risk of infection and complications like hypotony (too low pressure) or late scaring and failure of the bleb, are the reasons why trabeculectomy is mostly used only in severe glaucoma cases.