High-Resolution, Adaptive Optics Imaging of the Human Trabecular Meshwork In Vivo

Abstract

PurposeTo image the human trabecular meshwork (TM) in vivo using adaptive optics gonioscopy (AOG) with approximately 2-μm lateral resolution.MethodsAn existing Indiana University adaptive optics scanning laser ophthalmoscope was altered by adding a 12-mm button lens to a clinical gonioscopic lens allowing high-resolution imaging of the human iridocorneal angle. First an anatomic model eye was used to refine the imaging technique and then nine participants (7 controls and 2 participants with pigment dispersion syndrome) were imaged.ResultsAll nine participants were successfully imaged without adverse events. High-resolution imaging of the human TM was achieved allowing for visualization of the TM beams, and presumed endothelial cells. Uveal meshwork beams in controls averaged 25.5 μm (range, 15.2–44.7) in diameter with pores averaging 42.6 μm (range, 22.3–51.4) while the corneoscleral meshwork pores averaged 8.9 μm (range, 7.7–12.1). Differences in appearance of the uveal and corneoscleral meshwork were noted between the two participants with pigment dispersion syndrome and the controls. These included nearly absent spacing between the beams and enlarged endothelial cells with hyperreflective areas.ConclusionsAOG allows for near cellular level resolution of the human TM in vivo. This may allow for further understanding of age-related changes that occur as well as provide a deeper understanding of medical and surgical alterations for the treatment of glaucoma.Translational RelevanceFurther development of this approach may allow for direct measurements at a micometer level in vivo of changes that occur in the human trabecular meshwork with glaucoma and therapeutic interventions.

Tissue-Engineered Anterior Segment Eye Cultures Maintain Intraocular Pressure within a Normal Range<strong> </strong>

“…On the other hand, partially removing TM cells can also reduce IOP at least temporarily 47 . It has been previously shown that the presence of denuded TM beams can eventually fuse, associated with TM collapse, reduction of intertrabecular spaces for outflow, and pathologically elevated IOP [48][49][50][51][52][53] . Abu-Hassan et al 23 recently showed that the transplantation of human TM cells or TM-like iPSCs into the anterior segment perfusion model can restore outflow after killing about 1/3rd of TM cells with saponin.…”

The trabecular meshwork: Structure, function and clinical implications. A review of the literature

“…This provides imaging of the trabecular meshwork on a micron scale in vivo in humans. The images obtained show the trabecular beams and endothelial cells [114]. The development of this technique could allow direct in vivo measurements, on a micron scale, of the changes occurring in the human trabecular meshwork in glaucoma as well as after a therapeutic procedure.…”

Biofabrication of Artificial Stem Cell Niches in the Anterior Ocular Segment

“…It contains three structurally-distinct filtering regions: the inner uveal meshwork, which is the closest to the anterior chamber; the corneoscleral meshwork, which is the middle layer, and the juxtacanalicular tissue (JCT), which connects to the SC (see Figure 10) [232,233]. The uveal meshwork is made up of collagen and elastic lamellae in a "net-like" structure of beams around 25.5+/−15.6 µm thick, covered by TM cells, with intertrabecular spaces of around 42.6+/−19.6 µm [234]. The corneoscleral meshwork, contains thicker sections of porous collagen and elastin "beams" or "plates" with smaller intertrabecular spaces around 8.9+/−2.9 µm [234].…”

“…The uveal meshwork is made up of collagen and elastic lamellae in a "net-like" structure of beams around 25.5+/−15.6 µm thick, covered by TM cells, with intertrabecular spaces of around 42.6+/−19.6 µm [234]. The corneoscleral meshwork, contains thicker sections of porous collagen and elastin "beams" or "plates" with smaller intertrabecular spaces around 8.9+/−2.9 µm [234]. The JCT is a connective tissue between the corneoscleral meshwork and the basement membrane of Schlemm's canal and is mainly ECM surrounding TM cells with intertrabecular spaces between 0.5 and 2 µm [233,[235][236][237].…”