Bleb characteristics following minimally invasive bleb surgeries in relation to surgical success using the anterior segment optical coherence tomography - a systematic review.

PURPOSE: This systematic review aims to synthesize current literature on anterior segment optical coherence tomography (ASOCT) characteristics of blebs following minimally invasive bleb surgery (MIBS) using the XEN Gel Stent (XGS) and PreserFlo MicroShunt (PMS), and to evaluate their utility in predicting surgical success.

METHODS

A comprehensive search of MEDLINE, EMBASE, CENTRAL, and Scopus was conducted up to February 1, 2025, for studies evaluating ASOCT imaging of post-MIBS blebs. Eligible studies included adult patients with glaucoma who underwent MIBS and had ASOCT bleb imaging. Data on bleb morphology, surgical outcomes, and intraocular pressure (IOP) control were extracted.

RESULTS

Eleven studies comprising 409 participants were included. Surgical success following MIBS was associated with blebs with thicker walls, lower internal reflectivity, posterior episcleral fluid lakes, greater cystic structure density, and increased bleb height. Internal cavities and sub-conjunctival spaces were also consistently associated with lower IOP. XGS blebs often exhibited microcystic multiform or sub-conjunctival separation patterns, while PMS blebs demonstrated wider fluid cavities and closer proximity to the limbus. Implant positioning significantly affected bleb morphology and outcomes. Temporal evolution of bleb morphology following MIBS was also observed. Quantitative assessment via ASOCT faced limitations due to variability in imaging protocols and manual measurement methods.

CONCLUSION

ASOCT-based bleb imaging provides valuable structural insights that correlate with surgical success following MIBS. Further research with standardized imaging protocols may be needed to better refine bleb evaluation and examine longer-term surgical outcomes following MIBS.