Visualization of Scleral Flap Patency in Glaucoma Filtering Blebs Using OCT.
Tan Jeremy C K, Roney Matthew, Choudhary Anshoo, Batterbury Mark, Vallabh Neeru A
AI Summary
AS-OCT visualizes glaucoma bleb scleral flap patency. Free flap edges (often with MMC) correlate with surgical success, aiding objective bleb assessment beyond slit lamp.
Abstract
Purpose
To investigate the use of anterior-segment OCT (AS-OCT) to visualize the aqueous outflow pathway and patency of the scleral flap in glaucoma filtration surgery blebs.
Design
Cross-sectional study.
Subjects
Two hundred five filtering blebs of 112 patients with glaucoma who had undergone trabeculectomy (Trab, n = 97) or deep sclerectomy (DS, n = 108) surgery with/without mitomycin-C (MMC).
Methods
Swept-source AS-OCT raster slices were used to image the Trab and DS blebs in sagittal and coronal planes using a standardized protocol. Bleb appearances were classified into 4 categories based on the scleral flap and sclerostomy/trabeculo-descemet window (TDW) appearance: A-sclerostomy/TDW not visible; B-sclerostomy/TDW visible but scleral flap indiscriminate from sclera; C-scleral flap distinct but edges adherent to surrounding sclera; D-scleral flap edges non adherent to surrounding sclera.
Main outcome measures
Surgical outcomes were classified into complete success (CS) (intraocular pressure [IOP] ≤18 mmHg with no medications), qualified success (QS) (IOP ≤18 with medications), and failure (F) (IOP >18 mmHg).
Results
The proportions of CS, QS, and F in the Trab and DS cohorts were 45.0% and 29.6%, 33.0% and 31.5%, 22.0% and 38.9% respectively, with a median postoperative follow-up of 8.4 years (standard deviation 7.9; interquartile range 3.2-9.0). In QS and failed blebs, category C (Trab, 53.7%; DS, 52.5%) accounted for the majority of scleral flap appearances, followed by categories A and B. Category D (86.0%; 71.9%) accounted for the majority of appearances in Trab and DS blebs with CS. There was a significantly greater proportion of MMC use in categories C and D compared with categories A and B in both Trab ( P < 0.0001) and DS ( P = 0.02) cohorts, demonstrating the association of intraoperative MMC use with increased patency of the scleral flap.
Conclusions
Swept-source AS-OCT may be used to visualize the position and patency of the sclerostomy/TDW and scleral flap in relation to surrounding structures in both sagittal and coronal planes. Although free scleral flap edges are primarily correlated with MMC use, it may also correlate with surgical success. Anterior-segment OCT may be used to complement subjective bleb grading at the slit lamp in the assessment of filtering blebs.
Financial disclosures: The author(s) have no proprietary or commercial interest in any materials discussed in this article.
Shields Classification
Key Concepts4
In a cross-sectional study of 205 filtering blebs from 112 glaucoma patients, category D (scleral flap edges non-adherent to surrounding sclera) accounted for the majority of appearances in trabeculectomy (86.0%) and deep sclerectomy (71.9%) blebs with complete success (IOP ≤18 mmHg with no medications).
In a cross-sectional study of 205 filtering blebs from 112 glaucoma patients, category C (scleral flap distinct but edges adherent to surrounding sclera) accounted for the majority of scleral flap appearances in qualified success (IOP ≤18 with medications) and failed (IOP >18 mmHg) blebs from trabeculectomy (53.7%) and deep sclerectomy (52.5%) surgeries.
In a cross-sectional study of 205 filtering blebs from 112 glaucoma patients, there was a significantly greater proportion of mitomycin-C (MMC) use in categories C and D compared with categories A and B in both trabeculectomy (P < 0.0001) and deep sclerectomy (P = 0.02) cohorts, demonstrating the association of intraoperative MMC use with increased patency of the scleral flap.
Anterior-segment OCT (AS-OCT) can be used to visualize the aqueous outflow pathway and patency of the scleral flap in glaucoma filtration surgery blebs, specifically in trabeculectomy (Trab, n=97) or deep sclerectomy (DS, n=108) surgery with/without mitomycin-C (MMC).
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