Filtering blebs structure and function evaluation using optical coherence tomography

Daiva Paulaviciute-Baikstiene,Ingrida Januleviciene,Renata Vaiciuliene

doi:10.35119/maio.v1i2.15

Daiva Paulaviciute-Baikstiene, Ingrida Januleviciene + Show 1 more

Open Access

https://doi.org/10.35119/maio.v1i2.15

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Abstract

Purpose: To assess the ability of a noncontact optical coherence tomography to evaluate the morphological features of filtering blebs one year after glaucoma surgery.Design: Prospective study.Methods: Eighteen patients (18 eyes) with diagnosed primary open-angle glaucoma (POAG) assigned for trabeculectomy were included in the 12-month study carried out in the Eye clinic of the Lithuanian University of Health Sciences. All participants underwent trabeculectomy with 5-fluorouracil (5-FU). Bleb function was considered to be successful if the intraocular pressure (IOP) was ≤ 18 mmHg without glaucoma medications and a limited success if: 18 < IOP ≤ 21 mmHg with or without glaucoma medications at 12 months after surgery. The filtering blebs were imaged by anterior segment optical coherence tomography (AS-OCT) to evaluate the bleb wall reflectivity and measured bleb structures 12 months after trabeculectomy. Level of significance: p < 0.05 was considered significant.Results: The mean preoperative IOP was 25.7 (6.5) mmHg and the mean number of topical glaucoma medications was 3.0 (1.2). After surgery the mean IOP was 13.8 (3.4) mmHg and glaucoma medication was 0.3 (1.0) (Wilcoxon test, p < 0.001). Analyzing bleb morphology and bleb function it was found that with uniform wall reflectivity 0 out of 3 eyes (0%) had successful bleb function and with multiform wall reflectivity 14 out of 15 eyes (93.3%) had successful bleb function 12 months after surgery (p = 0.005).We found positive correlation between IOP changes and bleb wall thickness, height of internal fluid-filled cavity (bleb height) and total bleb height (r = 0.875, 0.897, 0.939, p < 0.001).Conclusion: AS-OCT is a useful device to assess the structure of the filtering bleb. Larger internal fluid-filled cavity, total bleb height, bigger bleb wall thickness and multiform bleb wall reflectivity were found to be good indicators of bleb function.

Highlights

Trabeculectomy is indicated for eyes with primary open-angle glaucoma (POAG) that have an inadequate intraocular pressure (IOP) with maximum tolerated medical therapy
Trabeculectomy is indicated for eyes with POAG that have an inadequate IOP with maximum tolerated medical therapy
We aimed to find the correlation between anterior segment optical coherence tomography (AS-OCT) and functional outcomes by describing morphological features of successful and limited success blebs

Summary

Introduction

Trabeculectomy is indicated for eyes with POAG that have an inadequate IOP with maximum tolerated medical therapy. The principle of the surgery is to reduce IOP by circumventing the outflow tract and allowing aqueous humor to exit beneath the scleral flap and under the conjunctiva where it forms a filtering bleb.[1] The success of this surgery depends on the functionality of the filtering bleb, aqueous humor drainage and IOP lowering effect.[2] in a significant number of cases aqueous humor filtration does not occur, because of obstruction of intrascleral aqueous flow and bleb fibrosis.[3] Bleb morphology has always been an important clinical parameter as an indicator for bleb function.[2] The description of bleb morphology and function is usually based on clinician’s subjective judgment. As assessed by slit-lamp biomicroscopy, is widely used to predict the possible functionality and the structure of blebs, but it is difficult to see internal structures, which may have an effect on bleb function.[3]

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