Aqueous Angiography: Real-Time and Physiologic Aqueous Humor Outflow Imaging

• Published in: PloS one Vol. 11; no. 1; p. e0147176
• Main Authors: Saraswathy, Sindhu, Tan, James C H, Yu, Fei, Francis, Brian A, Hinton, David R, Weinreb, Robert N, Huang, Alex S
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.01.2016; Public Library of Science (PLoS)
• Subjects: Angiography; Animals; Aqueous Humor - physiology; Biology and Life Sciences; Cataracts; Computer simulation; Computer Systems; Dextrans; Engineering and Technology; Eye; Fluorescein; Fluorescein Angiography - methods; Fluorescence; Fluorescent Dyes; Glaucoma; Humans; Image acquisition; Image processing; Image Processing, Computer-Assisted; Image quality; Intraocular pressure; Lumens; Medical imaging; Medicine; Medicine and Health Sciences; Mercury; Outflow; Real time; Research and Analysis Methods; Rheology - methods; Salts; Statistical analysis; Surgery; Sus scrofa; Swine; Tomography; Tomography, Optical Coherence; Los Angeles California; California; United States > US; Texas
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0147176

Trabecular meshwork (TM) bypass surgeries attempt to enhance aqueous humor outflow (AHO) to lower intraocular pressure (IOP). While TM bypass results are promising, inconsistent success is seen. One hypothesis for this variability rests upon segmental (non-360 degrees uniform) AHO. We describe aqueous angiography as a real-time and physiologic AHO imaging technique in model eyes as a way to simulate live AHO imaging. Pig (n = 46) and human (n = 6) enucleated eyes were obtained, orientated based upon inferior oblique insertion, and pre-perfused with balanced salt solution via a Lewicky AC maintainer through a 1mm side-port. Fluorescein (2.5%) was introduced intracamerally at 10 or 30 mm Hg. With an angiographer, infrared and fluorescent (486 nm) images were acquired. Image processing allowed for collection of pixel information based on intensity or location for statistical analyses. Concurrent OCT was performed, and fixable fluorescent dextrans were introduced into the eye for histological analysis of angiographically active areas. Aqueous angiography yielded high quality images with segmental patterns (p<0.0001; Kruskal-Wallis test). No single quadrant was consistently identified as the primary quadrant of angiographic signal (p = 0.06-0.86; Kruskal-Wallis test). Regions of high proximal signal did not necessarily correlate with regions of high distal signal. Angiographically positive but not negative areas demonstrated intrascleral lumens on OCT images. Aqueous angiography with fluorescent dextrans led to their trapping in AHO pathways. Aqueous angiography is a real-time and physiologic AHO imaging technique in model eyes.