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

• Published in: Ophthalmology science (Online) Vol. 1; no. 4; p. 100080
• Main Authors: Lee, Jong Yeon, Heilweil, Gad, Le, Phuc, Saraswathy, Sindhu, Hong, Young-Kwon, Girkin, Christopher A, Huang, Alex S
• Format: Journal Article
• Language: English
• Published: Netherlands 01.12.2021
• Subjects: Ophthalmology; Blebs; Lymphatics; Conjunctiva; Aqueous Outflow; Glaucoma Surgery; Subconjunctival
• ISSN: 2666-9145; 2666-9145
• DOI: 10.1016/j.xops.2021.100080

PurposeTo uncover the mechanism of subconjunctival outflow in human patients. DesignCross-sectional study Subjects/Participants and/or ControlsFifteen subjects receiving subconjunctival anesthesia prior to intravitreal injection for routine clinical care. MethodsAnterior 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 MeasuresOcular surface lymphangiography and AS-OCT images. ResultsAS-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. DiscussionOutflow 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.