A qualitative and quantitative analysis of filtering blebs with optical coherence tomography in patients after primary trabeculectomy

Napoli P. E;ZUCCA, IGNAZIO ALBERTO;FOSSARELLO, MAURIZIO

2012-01-01

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Abstract

Purpose: To provide a qualitative and quantitative analysis of filtering blebs with optical coherence tomography (OCT) in patients after primary trabeculectomy. Methods: We retrospectively studied 27 eyes of 25 patients who had a fornix-based flap in primary trabeculectomy: 21 with mitomycin C (MMC) and 6 without MMC. Successful blebs were defined by intraocular pressure (IOP) ≤ 18 mmHg without medication or additional surgery. Filtering blebs were examined using two types of OCTs working at a wavelength of 840 nm and 1310 nm. In this study, we analyzed the OCT morphological-pattern and quantified the reflectivity of blebs. The period between trabeculectomy and OCT examination ranged from 1 week to 2 years. Results: Blebs were classified on the basis of OCT morphological-pattern into three different categories: cystoid type, diffuse type and layer type. The MMC was associated with successful blebs (100%). A significant association was found between bleb good functionality and cystoid-pattern with both devices: 840-nm OCT (p=0.01) and 1310-nm OCT (p=0.03). The reflectivity of filtering blebs correlated very well to the postoperative IOP (R2= 0.90; p<0.001) and to the reduction of IOP (R2= 0.38; p= 0.001). A significant difference (p= 0.02) in characteristics of bleb morphology was found using 840-nm OCT and 1310-nm OCT. Conclusions: A highly significant association of bleb reflectivity to the degree of functionality could be shown. Although 840-nm OCT was not developed to assess the anterior segment, it may be considered a useful tool to evaluate the functionality of blebs in the post-operative period.