Qualitative and quantitative analysis of filtering blebs with optical coherence tomography

Area of Science:

• Ophthalmology
• Surgical Technology
• Medical Imaging

Background:

• Trabeculectomy is a primary surgical treatment for glaucoma.
• Filtering blebs are crucial for successful trabeculectomy outcomes.
• Assessing bleb functionality post-surgery is vital for managing intraocular pressure (IOP).

Purpose of the Study:

• To qualitatively and quantitatively analyze filtering blebs using optical coherence tomography (OCT) after primary trabeculectomy.
• To evaluate the utility of two OCT devices (840 nm and 1310 nm) in assessing bleb morphology and internal structures.
• To correlate OCT findings with surgical success and postoperative IOP.

Main Methods:

• Retrospective analysis of 20 eyes undergoing primary trabeculectomy with fornix-based flaps.
• Examination of filtering blebs using 840 nm and 1310 nm OCT devices.
• Analysis of OCT morphologic patterns (cystoid, diffuse, layer), bleb wall/scleral flap thickness, and quantification of intrableb reflectivity.

Main Results:

• Blebs were classified into cystoid, diffuse, and layer types using the Hirooka scheme.
• Mitomycin C (MMC) was associated with 100% surgical success.
• A significant association between good bleb functionality and the cystoid type was observed with both OCT devices (p=0.02 and p=0.04).
• Bleb reflectivity strongly correlated with postoperative IOP (R²=0.90) and IOP reduction (R²=0.58).
• The quantification method for reflectivity demonstrated high intergrader consensus (ICC=0.99).

Conclusions:

• Both 840 nm and 1310 nm OCT are useful for evaluating filtering blebs post-trabeculectomy.
• OCT can assess bleb morphology and internal structures, correlating with surgical outcomes.
• The reflectivity measurement using OCT is a reliable quantitative tool for predicting IOP control after surgery.