Ab Externo Imaging of Human Episcleral Vessels Using Fiberoptic Confocal Laser Endomicroscopy

• Published in: Journal of ophthalmic & vision research Vol. 14; no. 3; pp. 275 - 284
• Main Authors: Y Lin, Ken, Mosaed, Sameh
• Format: Journal Article
• Language: English
• Published: United Arab Emirates PUBLISHED BY KNOWLEDGE E 01-07-2019; Knowledge E
• Subjects: Aqueous Outflow; Laser Imaging; Minimally Invasive Glaucoma Surgery; Original; Laser Imaging; Aqueous Outflow; Minimally Invasive Glaucoma Surgery
• ISSN: 2008-2010; 2008-322X
• DOI: 10.18502/jovr.v14i3.4783

There is a growing interest in targeting minimally invasive surgery devices to the aqueous outflow system to optimize treatment outcomes. However, methods to visualize functioning, large-caliber aqueous and episcleral veins
are lacking. This pilot study establishes an
system to evaluate the use of a confocal laser microendoscope to noninvasively image episcleral vessels and quantify regional flow variation along the limbal circumference.
A fiber-optic confocal laser endomicroscopy (CLE) system with lateral and axial resolution of 3.5
m and 15
m, respectively, was used on three porcine and four human eyes. Diluted fluorescein (0.04%) was injected into eyes kept under constant infusion. The microprobe was applied to the sclera 1 mm behind the limbus to acquire real-time video. Image acquisition was performed at 15-degree intervals along the limbal circumference to quantify regional flow variation in human eyes.
Vascular structures were visualized in whole human eyes without processing. Schlemm's canal was visualized only after a scleral flap was created. Fluorescent signal intensity and vessel diameter variation were observed along the limbal circumference, with the inferior quadrant having a statistically higher fluorescein signal compared to the other quadrants in human eyes (
< 0.05).
This study demonstrates for the first time that the fiber-optic CLE platform can visualize the episcleral vasculature with high resolution
with minimal tissue manipulation. Intravascular signal intensities and vessel diameters were acquired in real-time; such information can help select target areas for minimally invasive glaucoma surgery (MIGS) to achieve greater intraocular pressure reduction.