No Correlation of Structural Anterior-Segment OCT Biomarkers with Bleb Vessel Density and Surgical Success after Preserflo Microshunt Implantation

Purpose To evaluate anterior segment optical coherence tomography (AS-OCT) parameters of bleb wall thickness (BWT) and total bleb height (TBH) in the early postoperative phase after Preserflo Microshunt (PM) implantation for their correlation to (a) surgical revision and (b) AS-OCT angiography (AS-OCTA) derived bleb vessel density (BVD). Methods A total of 23 patients with pharmacologically uncontrolled open angle glaucoma were studied. Post-operatively (at 1, 2, and 4 weeks and 2, 3, 6, 9, and 12 months) AS-OCT measurements of BWT/TBH and AS-OCTA measurements of BVD were acquired. Surgical revisions (needling or open revision) were recorded. Correlations of BWT and TBH to (a) need for surgical revision and to (b) BVD were assessed. Results In 10 of 23 patients, surgical revisions were performed 4 to 48 weeks after PM implantation. At 1, 2, and 4 weeks after surgery neither BWT nor TBH were significantly associated with future surgical revisions (BWT/TBH p-values: 1W 0.217/0.878, 2W 0.670/0.528, 4W 0.171/0.430). No correlations between BWT or TBH and BVD were found for any evaluated timepoint (1W, 2W, 4W). Conclusions Structural AS-OCT parameters were not predictive of the need for surgical revision after PM implantation. Consistent with this finding, these parameters were also not correlated with AS-OCTA derived BVD, which was shown to be a good biomarker for failure in a previous analysis. The discrepancy to similar studies after trabeculectomy may be due to bleb drainage differences between TE and PM. BVD seems to be a better predictor of surgical revision after PM implantation than BWT/TBH.