Sir,
An overhanging bleb, a rare complication of trabeculectomy, can cause discomfort and decreased visual acuity in which case surgical removal is necessary. But, surgical removal is not free of possible risks such as leakage. We present a case in which a dissecting portion of bleb was successfully removed without leaking, with an aid of preoperative anterior segment optical coherence tomography (AS-OCT).
Case report
A 47-year-old woman visited our clinic due to visual disturbance (10/200 without correction) on her left eye. She received trabeculectomy 13 years ago. On slit-lamp examination, an overhanging filtration bleb was noted (Figure 1a). Before the surgery, AS-OCT (SL-OCT™, Heidelberg Engineering GmbH, Germany) was taken (Figure 2). The dissecting portion of the bleb over the cornea was removed with forceps and scissors. The histopathologic image of removed bleb was consistent with the imaging of AS-OCT, multiloculated cystic structures (Figure 3). One day after operation, there was no leakage around excision margin. Until 6 months after surgery (Figure 1b), the patient showed good visual acuity (20/40–20/50) and IOP (14–18 mmHg) without leaking.
Comment
Surgeons generally find it uncomfortable to manipulate trabeculectomy bleb due to the risk of leaking. Obtaining preoperative knowledge of bleb structures appears feasible in planning safe surgery beforehand to reduce the risk of complications from manipulation. Noninvasive approaches to examine bleb include ultrasound biomicroscopy and AS-OCT.1, 2 In our case, multiloculated bleb structure of dissecting portion apart from the main cystic bleb was confirmed by preoperative AS-OCT imaging and histological study. Previous reports of overhanging bleb3, 4, 5 stated that leaking was not a common complication even without the safety measure or suture. No leakage of aqueous humour or fast healing might be due to multicystic structures of the overhanging bleb in which the exchange of aqueous humour is suppressed.
We believe our experience with this case help readers understand the physical characteristics of overhanging blebs, as well as the feasibility of AS-OCT in planning safe surgery before bleb manipulation. However, more research and experiences should be carried out to bring up a general conclusion, which can be applied in all overhanging bleb cases.
References
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Singh M, Chew PT, Friedman DS, Nolan WP, See JL, Smith SD et al. Imaging of trabeculectomy blebs using anterior segment optical coherence tomography. Ophthalmology 2007; 114: 47–53.
Grostern RJ, Torczynski E, Brown SV . Surgical repair and histopathologic features of a dissecting glaucoma filtration bleb. Arch Ophthalmol 1999; 117: 1566–1567.
Anis S, Ritch R, Shihadeh W, Liebmann J . Sutureless revision of overhanging filtering blebs. Arch Ophthalmol 2006; 124: 1317–1320.
Ito K, Miura K, Sugimoto K, Malsunaga K, Susoh M, Uji Y . Use of indocyanine green during excision of an overhanging filtering bleb. Jpn J Ophthalmol 2007; 51: 57–59.
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Kim, W., Seong, G., Lee, C. et al. Anterior segment optical coherence tomography imaging and histopathologic findings of an overhanging filtering bleb. Eye 22, 1520–1521 (2008). https://doi.org/10.1038/eye.2008.166
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DOI: https://doi.org/10.1038/eye.2008.166
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