Fig. 2

Appearance of corneal invasion by filtering bleb (CIFB), overhanging filtering bleb (OFB), and giant filtering bleb on slit lamp examination. A: Early-stage CIFB. In the early stage after filtering surgery, the subconjunctival tissue at the posterior boundary of the filtering bleb exhibits an adhesion, leading to the sinking of the conjunctiva and the formation of a conjunctival settlement line (arrow). B: Moderate CIFB. The posterior boundary of the bleb is obviously limited due to adhesion, and the anterior boundary is serrated and invades into the corneal stroma. The filtering bleb has no sagging feeling and cannot be pushed. C: Severe CIFB. The bleb is tightly attached to the cornea. There is no sagging feeling, and the bleb cannot be pushed. D: Moderate OFB. The bleb hanging over the corneal surface can be pushed upward, and the light slit is bent in a barbed shape at its lower edge. E: Severe OFB. The bleb is partially fused with the corneal epithelium, and serrated adhesion can be seen at its anterior boundary. F: Giant filtering bleb. The bleb has expanded over a large area without any obvious adhesion. The anterior boundary has crossed the limbus and entered the corneal area, and adhered with the corneal surface to some extent