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

To compare characteristics of functioning blebs (FBs) and nonfunctioning blebs (NFBs) with en-face spectral-domain optical coherence tomography (OCT).

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 semiquantitatively 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.

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).

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.