Updates on the utility of anterior segment optical coherence tomography in the assessment of filtration blebs after glaucoma surgery

Abstract

The formation of filtration blebs is the main drainage mechanism for reducing intraocular pressure after traditional incisional glaucoma surgery such as trabeculectomy and non‐penetrating deep sclerotomy. Early and short‐lasting blebs may also occur after canaloplasty. Bleb formation also plays an important role after the implantation of glaucoma drainage devices, including Minimally Invasive Glaucoma Surgery devices. Anterior segment optical coherence tomography (AS‐OCT) is a rapid and non‐invasive high‐resolution imaging technique that has evolved in recent years to become a routine examination. Anterior segment optical coherence tomography (AS‐OCT) provides key information in the assessment and follow‐up of glaucoma surgery, especially in the assessment of filtration blebs. Thus, bleb morphology can be qualitatively classified into diffuse, cystic, encapsulated and flattened, and AS‐OCT imaging can also provide several quantitative parameters of the bleb, such as total bleb height, bleb fluid‐filled cavity height, bleb wall thickness, number of microcysts and trabeculectomy opening size. These parameters could have an impact on clinical management during follow‐up because they may predict the success or failure of the surgery in the early and late postoperative periods. Additionally, they may also guide the procedures used to increase filtration and reduce intraocular pressure, such as bleb needling and laser suture lysis.

Novel Bleb Classification Following Ab Interno Implantation of Gel-Stent Using Anterior Segment Optical Coherence Tomography

“…1 Many classification systems have been presented to evaluate the bleb morphology and correlate it to the resulting IOP and need for further interventions or determining follow-up intervals. 2,3 The use of anterior segment optical coherence tomography (AS-OCT) to evaluate bleb after filtering glaucoma surgery has dramatically increased in the last years as it offers an objective and reproducible assessment tool [4][5][6][7] compared with sole subjective appraisal using biomicroscopy or photography. AS-OCT may even offer a better prognostic evaluation of the bleb compared with clinical examination.…”

“…The use of anterior segment optical coherence tomography (AS-OCT) to evaluate bleb after filtering glaucoma surgery has dramatically increased in the last years as it offers an objective and reproducible assessment tool4–7 compared with sole subjective appraisal using biomicroscopy or photography. AS-OCT may even offer a better prognostic evaluation of the bleb compared with clinical examination 8,9.…”

Efficacy and Safety of the Intraoperative Application of Mitomycin in Glaucoma Patients with Trabeculectomy: A Systematic Review and Meta-Analysis

“…Tis was also confrmed by a Taiwanese study [24] and the study by Jabeen et al [25]. Te formation of functional fltering blebs is an important indicator of the success of trabeculectomy [26,27], but it is more of an assessment of the short-term efects. Tis study found that after the application of MMC, the formation of functional fltering vesicles was signifcantly better than that of the control group (RR: 1.18, 95% CI: 1.09 to 1.27), and the included studies had low heterogeneity (I 2 � 0%), suggesting that in this indicator, the results of the studies are very consistent.…”

Single versus Double PreserFlo MicroShunt Implantation in Glaucoma Patients: A Retrospective Cohort Study

“…Trabeculectomy is known to form distinct types of bleb morphologies. Recent studies have shown that MIGS drainage devices lead to similar bleb morphologies [25]. However, as the external end of the PreserFlo MicroShunt is placed under the Tenon’s capsule, this type of MIGS drainage type has been shown to cause a large and distinct fluid accumulation between the sclera and Tenon’s capsule in addition to the pre-known appearance of intra-/subconjunctival fluid distributions.…”