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Understanding aqueous outflow resistance at the level of aqueous veins has been a challenge to the management of glaucoma. This study investigated resolving the anatomies of aqueous veins and the textures of surrounding sclera using photoacoustic microscopy (PAM). A dual wavelength PAM system was established and validated using imaging phantoms, porcine and human globes perfused with an optical contrast agentex vivo. The system shows lateral resolution of 8.23 µm and 4.70 µm at 1200 nm and 532 nm, respectively, and an axial resolution of 27.6 µm. The system is able to separately distinguish the aqueous veins and the sclera with high contrast in full circumference of the porcine and human globes.

 

High‐quality‐factor microring resonators are highly desirable in many applications. Fabricating a microring resonator typically requires delicate instruments to ensure a smooth side wall of waveguides and 100‐nm critical feature size in the coupling region. In this work, a new method “damascene soft nanoimprinting lithography” is demonstrated that can create high‐fidelity waveguide by simply backfilling an imprinted cladding template with a high refractive index polymer core. This method can easily realize high Q‐factor polymer microring resonators (e.g., ≈5 × 10⁵around 770 nm wavelength) without the use of any expensive instruments and can be conducted in a normal lab environment. The high Q‐factors can be attributed to the residual layer‐free feature and controllable meniscus cross‐section profile of the filled polymer core. Furthermore, the new method is compatible with different polymers, yields low fabrication defects, enables new functionalities, and allows flexible substrate. These benefits can broaden the applicability of the fabricated microring resonator.

 

Abstract A method motivated by the eye’s aqueous veins is described for the imaging and strain calculation within soft biological tissues. A challenge to the investigation of the biomechanics of the aqueous vein—perilimbal sclera tissue complex is resolution of tissue deformations as a function of intraocular pressure and the subsequent calculation of strain (a normalized measure of deformation). The method involves perfusion of the eye with a contrast agent during conduction of non-invasive, optical resolution photoacoustic microscopy. This imaging technique permits three-dimensional displacement measurements of tracked points on the inner walls of the veins which are used in a finite element model to determine the corresponding strains. The methods are validated against two standard strain measurement methods. Representative porcine globe perfusion experiments are presented that demonstrate the power of the method to determine complex strain fields in the veins dependent on intraocular pressure as well as vein anatomy. In these cases, veins are observed to move radially outward during increases in intraocular pressure and to possess significant spatial strain variation, possibly influenced by their branching patterns. To the authors’ knowledge, these are the only such quantitative, data driven, calculations of the aqueous vein strains available in the open literature.