title: Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography.
abstract: The aqueous outflow system (AOS) is responsible for maintaining normal intraocular pressure (IOP) in the eye. Structures of the AOS have an active role in regulating IOP in healthy eyes and these structures become abnormal in the eyes with glaucoma. We describe a newly developed system platform to obtain high-resolution images of the AOS structures. By incorporating spectral domain optical coherence tomography (SD-OCT), the platform allows us to systematically control, image, and quantitate the responses of AOS tissue to pressure with a millisecond resolution of pulsed flow. We use SD-OCT to image radial limbal segments from the surface of the trabecular meshwork (TM) with a spatial resolution of ∼5  μm in ex vivo nonhuman primate eyes. We carefully insert a cannula into Schlemm’s canal (SC) to control both pressures and flow rates. The experimental results demonstrate the capability of the platform to visualize the unprecedented details of AOS tissue components comparable to that delivered by scanning electron microscopy, as well as to delineate the complex pressure-dependent relationships among the TM, structures within the SC, and collector channel ostia. The described technique provides a new means to characterize the anatomic and pressure-dependent relationships of SC structures, particularly the active motion of collagenous elements at collector channel ostia; such relationships have not previously been amenable to study. Experimental findings suggest that continuing improvements in the OCT imaging of the AOS may provide both insights into the glaucoma enigma and improvements in its management.
authors.affiliation: University of Washington, Department of Bioengineering, Seattle, Washington 98195, United States.
authors.forename: Sepideh
authors.initials: S
authors.lastname: Hariri
authors.affiliation: University of Washington, Department of Ophthalmology, Seattle, Washington 98195, United States.
authors.forename: Murray
authors.initials: M
authors.lastname: Johnstone
authors.affiliation: University of Washington, Department of Ophthalmology, Seattle, Washington 98195, United States.
authors.forename: Yi
authors.initials: Y
authors.lastname: Jiang
authors.affiliation: University of Washington, Department of Ophthalmology, Seattle, Washington 98195, United States.
authors.forename: Steven
authors.initials: S
authors.lastname: Padilla
authors.affiliation: University of Washington, Department of Bioengineering, Seattle, Washington 98195, United StatescBeijing Information Science and Technology University, Beijing Laboratory of Biomedical Detection Technology and Instruments, Beijing 100192, China.
authors.forename: Zhehai
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: University of Washington, Department of Bioengineering, Seattle, Washington 98195, United States.
authors.forename: Roberto
authors.initials: R
authors.lastname: Reif
authors.affiliation: University of Washington, Department of Bioengineering, Seattle, Washington 98195, United StatesbUniversity of Washington, Department of Ophthalmology, Seattle, Washington 98195, United States.
authors.forename: Ruikang K
authors.initials: RK
authors.lastname: Wang
mesh_terms: D000818:Animals; D000867:Anterior Chamber / Q000033:anatomy & histology* / Q000502:physiology; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007429:Intraocular Pressure; D008251:Macaca; D041623:Tomography, Optical Coherence / Q000379:methods*; D014129:Trabecular Meshwork / Q000033:anatomy & histology* / Q000502:physiology