Current methods and new approaches to assess aqueous humor dynamics

Abstract

Introduction: Aqueous humor and its dynamics (AHD) serve numerous functions to sustain ocular health and clear vision. Current methods to assess AHD have led to improved understanding of ocular physiology, pathologies caused by abnormal intraocular pressures (IOP), and treatments to return IOP to healthy levels. However, the assumptions and limitations inherent in these methods have been problematic. New methods on the horizon are showing promise to greatly advance the field.Areas covered: This review summarizes AHD assessment techniques in use today including the noninvasive methods of fluorophotometry, tonometry, tonography, venomanometry, and invasive methods of cannulation, infusion, dissection. It also mentions emerging methods utilizing advanced imaging methods, smart phones, cameras, and software. Expert opinion: Soon new techniques will become available to measure each parameter and even subparts of each parameter of AHD with increased speed, accuracy, and safety. Along with these new methods and the data they generate could emerge the next version of the Goldmann Equation. These new methods would make AHD an important tool in the clinic for precision medicine and in the lab for exploring AHD on a new level.

The Glymphatic System (En)during Inflammation

“…Similarly to the brain, the eye produces its own fluid, known as the aqueous humor. Aqueous humor drains out of the eye via the anterior chamber and Schlemm’s canal, although some fluid can also leave by uveoscleral drainage [ 49 , 50 ]. Yet, the neuroretina in the back of the eye is metabolically the most active part of the eye, and is thus in need of a fluid-transport mechanism to remove neurotoxic waste products.…”

Analysis of nestin protein in the aqueous humor as biomarker of open angle glaucoma

“…Accordingly, one chance is to use AH for QCM nestin detection instead of wasting this fluid after ocular surgery. AH sampling is going to be easier in the next future using new minimally invasive device [ 23 ]. At this regard, QCM would be an interesting method to be used because the minimal volume (30–40 ul) of samples required and the advantage of avoiding any purification of extraction steps.…”

International consortium for innovation and quality: An industry perspective on the nonclinical and early clinical development of intravitreal drugs

“…The AH is secreted by the epithelium lining the ciliary processes into the posterior chamber, and circulates toward the anterior chamber via the pupil. There, it flows across the corneal endothelium and anterior iris limiting membrane before exiting the eye through the iridocorneal angle (ICA) via the trabecular outflow path (Schlemm's canal and into the aqueous and episcleral veins) or the uveoscleral outflow path (ciliary body into the sclera and choroid veins) 4,5 . Differences in the AH outflow rate may limit ocular drug retention in some species, which can be compensated by increasing the frequency of intracameral and IVT injections during the conduct of toxicity studies.…”