Structural imaging of conjunctival filtering blebs in XEN gel implantation and trabeculectomy: a confocal and anterior segment optical coherence tomography study

Matteo Sacchi, Luca Agnifili, Lorenza Brescia, Francesco Oddone, Edoardo Villani, Paolo Nucci, Leonardo Mastropasqua

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: To describe and compare the conjunctival filtering bleb features after XEN gel implantation and trabeculectomy using anterior segment optical coherence tomography (AS-OCT) and in vivo confocal microscopy (IVCM). Methods: Fifty-two patients who underwent completely successful trabeculectomy (24 eyes) or completely successful XEN gel implantation (28 eyes) were consecutively enrolled. At the sixth-month follow-up, filtering blebs were analyzed with AS-OCT and IVCM. The main outcomes were the following: (i) bleb-wall epithelium cyst-like structure density and area (BECSD, BSCSA), (ii) bleb-wall sub-epithelium cyst-like structure density and area (BSCSD, BSCSA,), (iii) bleb-wall thickness (BT), (iv) bleb-wall epithelial thickness (BET), (v) bleb-wall reflectivity (BR), and (vi) bleb height (BH), for AS-OCT. Mean microcyst density (MMD) and area (MMA) and stromal meshwork reflectivity (SMR) were the IVCM outcomes. Results: Six-month intraocular pressure was 11.46 ± 3.09 and 10.06 ± 3.39 mmHg in the XEN gel implantation and trabeculectomy, respectively (p > 0.05). At AS-OCT, XEN gel blebs showed lower BH, BT, BET, BR, (p < 0.001), and BECSA values (p < 0.005), and a higher BECSD (p < 0.05) compared with trabeculectomy blebs. At IVCM, MMA and SMR values were lower in the XEN gel implantation, compared with trabeculectomy (p < 0.05). BECSD and BSCSD negatively correlated with BR (p < 0.01; r = − 0.110; p < 0.01; r = − 0.249), whereas BR strongly correlated with SMR (p < 0.001; r = 0.819). Conclusion: Successful filtering blebs after XEN gel implantation appeared flatter and thinner, with a higher number of epithelial cysts and a hypo-reflective bleb wall compared with trabeculectomy. These aspects may depend on the different intra-operative tissue manipulation and/or on different aqueous humor dynamics in the sub-conjunctiva between surgeries.

Original languageEnglish
Pages (from-to)1763-1770
Number of pages8
JournalGraefe's Archive for Clinical and Experimental Ophthalmology
Volume258
Issue number8
DOIs
Publication statusPublished - Aug 1 2020

Keywords

  • Anterior segment optical coherence tomography
  • Filtration blebs
  • Glaucoma
  • In vivo confocal microscopy
  • Trabeculectomy
  • XEN gel implantation

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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