Structural Confirmation of Lymphatic Outflow from Subconjunctival Blebs of Live Human Subjects

Jong Yeon Lee; Gad Heilweil; Phuc Le; Sindhu Saraswathy; Young-Kwon Hong; Christopher A Girkin; Alex S Huang

doi:10.1016/j.xops.2021.100080

Structural Confirmation of Lymphatic Outflow from Subconjunctival Blebs of Live Human Subjects

Ophthalmol Sci. 2021 Dec;1(4):100080. doi: 10.1016/j.xops.2021.100080. Epub 2021 Nov 15.

Authors

Jong Yeon Lee^{1

2}, Gad Heilweil¹, Phuc Le¹, Sindhu Saraswathy¹, Young-Kwon Hong³, Christopher A Girkin⁴, Alex S Huang⁵

Affiliations

¹ Doheny Eye Institute and Stein Eye Institute, Department of Ophthalmology, David Geffen School of Medicine, University of California, Los Angeles, USA.
² Department of Ophthalmology, Gachon University College of Medicine, Gil Medical Center, Incheon, Korea.
³ Department of Surgery, Norris Comprehensive Cancer Center Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
⁴ Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, AL, USA.
⁵ The Viterbi Family Department of Ophthalmology, Shiley Eye Institute, University of California, San Diego, CA, USA.

Abstract

Purpose: To uncover the mechanism of subconjunctival outflow in human patients.

Design: Cross-sectional study.

Subjects/participants and/or controls: Fifteen subjects receiving subconjunctival anesthesia prior to intravitreal injection for routine clinical care.

Methods: Anterior segment OCT (AS-OCT) was performed in patients with various instances of conjunctival edema or subconjunctival fluid. Other subjects received a subconjunctival mixture of 0.005% indocyanine green and 2% lidocaine. After subconjunctival injection of the tracer/anesthetic mixture, blebs and associated outflow pathways were angiographically imaged and the time for appearance recorded. The pattern and structure of outflow pathways were studied using AS-OCT. Angiographic and AS-OCT results were compared to trabecular/conventional outflow imaging which demonstrates veins.

Main outcome measures: Ocular surface lymphangiography and AS-OCT images.

Results: AS-OCT of the conjunctiva in a normal eye demonstrated thin non-edematous conjunctiva with absent intraconjunctival lumens or subconjunctival fluid. Subjects with a history of trabeculectomy, subconjunctival drug injection, or chemosis demonstrated thickened conjunctiva and intraconjunctival luminal pathways that contained valve-like structures. Tracer-based studies in patients demonstrated blebs with irregular subconjunctival bleb-related outflow patterns that arose in a time-dependent fashion. These angiographic pathways were luminal on OCT, sausage-shaped, and contained intraluminal valve-like structures. This was in contrast to trabecular/conventional outflow imaging where pathways were classically Y-shaped, of even-caliber, and lacked valve-like structures.

Discussion: Outflow pathways were seen in cases of conjunctival edema and after subconjunctival tracer injection. These pathways were lymphatic based upon pattern and structural study. Better understanding of bleb-related lymphatic outflow may lead to improved bleb-requiring glaucoma surgeries and subconjunctival drug delivery.

Keywords: Aqueous Outflow; Blebs; Conjunctiva; Glaucoma Surgery; Lymphatics; Subconjunctival.

Abstract

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