Trabeculectomy is an operation that create a square window at the top of the eye underneath the eye lid. This will allow the water from inside the eye draining out through the guarded window, the excessive fluid is then drained into a resorvior like space covered by the conjunctiva tissue and form an elevation called 'the bleb'. This will result in lowering the eye pressure and prevent further damage of the optic nerve and hence vision loss.