Evaluation of Blebs After Filtering Surgery With En-Face Anterior-Segment Optical Coherence Tomography: A Pilot Study

Purpose: To compare characteristics of functioning blebs (FBs) and nonfunctioning blebs (NFBs) with en-face spectral-domain optical coherence tomography (OCT). Methods: We evaluated 41 blebs of 38 patients after a first-time trabeculectomy. Eyes were classified into 2 groups: FBs (22 eyes) and NFBs (19 eyes). En-face OCT images were analyzed semi-quantitatively for the density of intraepithelial microcysts (0 to 3), internal fluid-filled cavity (0 to 3), and bleb vascularization (0 to 2). Presence of conjunctival fibrosis and visualization of the scleral flap were also analyzed. Results: FBs showed significantly more intraepithelial microcysts than did NFBs: the mean grading of microcyst density was 1.86 for FBs and 0.11 for NFBs (P < 0.0001). None of the FBs were rated 0 and none of the NFBs were rated 2 or 3 for the density of intraepithelial microcysts. NFBs presented more conjunctival fibrosis than FBs (63% vs. 32%, P < 0.05). There was no significant difference between FBs and NFBs for bleb vascularization, visualization of the scleral flap, and presence of subepithelial fluid-filled cavities. There was a direct correlation between postoperative intraocular pressure and intraepithelial microcyst density (r = -0.7655, P < 0.0001). The long-term administration of preserved eyedrops before surgery was associated with fewer intraepithelial microcysts (r = -0.5436; P = 0.0006). Conclusions: FBs were associated with a higher number of intraepithelial microcysts evaluated with en-face OCT. A higher density of microcysts was associated with a lower intraocular pressure and a shorter duration of preserved topical treatment before surgery. En-face OCT provides a simple, noninvasive, and reproducible method to analyze blebs after filtering surgery.