Imaging of trabecular meshwork using Bessel–Gauss light sheet with fluorescence

Abstract

Ocular imaging technology that holds promise for both fundamental investigation and clinical detection of glaucoma is still a challenging research area. A direct view of the trabecular meshwork (TM) with high resolution is not generally possible because the iridocorneal angle region is obstructed by the sclera overlap. The best approach to observe the aqueous outflow system (AOS) is therefore to view from the opposite angle. In this research work, we developed two imaging systems for the high resolution ex vivo studies of the AOS inside porcine eye, based on a Gaussian illuminated and a digitally scanned Bessel-Gauss beam light sheet fluorescence configurations. The digitally scanned Bessel-Gauss beam is able to overcome the trade-off between the length and thickness of the Gaussian light sheet to give better imaging performance. It has adequate spatial resolution to resolve critical anatomical structures such as the TM, thereby enabling objective information about the AOS. This noncontact and non-invasive imaging methodology with excellent safety profile is expected to be well received by vision researchers and clinicians in the evaluation and management of glaucoma.

Optical sectioning and high resolution visualization of trabecular meshwork using Bessel beam assisted light sheet fluorescence microscopy

“…The invariant intensity over a large focal region and the self‐reconstructive property of the Bessel beam makes it an ideal source for illuminating structures within scattering media. Additionally, the scanned light sheet illuminates the sample with identical intensity at each scanned line, and enables quantitative analysis of large samples in their natural state . The adopted method of generating the Bessel beam using an axicon lens can be easily implemented and is more efficient than traditional methods such as the illumination of an annular mask .…”

“…This technique can generate high resolution two‐dimensional optical sections of the samples under investigation . With this perspective we consider Bessel beam‐based scanned light sheet fluorescence microscopy (LSFM), as a potential imaging modality that can produce high resolution optical sections with minimal phototoxicity and photobleaching . The high speed data acquisition and low photodamage of this technique make it an ideal candidate for in vivo ocular imaging.…”

“…The invariant resolution across a large field of view and the ability to generate high signal to noise ratio images makes this diagnostic technique a robust tool for the high resolution imaging of TM structures. We have previously reported ICA imaging based on this technique , however it was lacking high resolution, large field of view imaging and optical sectioning capabilities.…”

Noninvasive and Noncontact Sequential Imaging of the Iridocorneal Angle and the Cornea of the Eye

“…Additionally, this positioning improves the image sharpness and reduces background noise. 26 The proposed LSFM scheme has an intrinsic optical sectioning capability, because no fluorescence is generated beyond the illumination plane, minimizing the out-of-focus background.…”

“…With minor modifications, the excitation arm of the proposed ICA imaging system can be adapted for high-resolution corneal imaging. Although we have reported the Bessel beam light sheet fluorescence microscopy (LSFM)based ICA imaging system and Gaussian beam based corneal imaging system in the past, 25,26 a method to integrate these two techniques to a single system that can be used for both corneal imaging and ICA imaging is reported in this work. Further the in vivo and ex vivo imaging capabilities of this system are also demonstrated as proof of concept.…”