[Imaging of the Intrascleral Aqueous Drainage System - New Insights for Glaucoma Surgery Targeting the Trabecular Meshwork].

Numerous new techniques in glaucoma surgery target the trabecular meshwork, which is considered to be the main site of aqueous outflow resistance. These approaches rely on a functioning aqueous drainage system distal to the site of surgery. Thus, the intrascleral aqueous outflow tract comprises Schlemm's canal, collector channels and aqueous veins and has become an object of increasing research interest. The intrascleral outflow tract contributes approximately 25-50 % to the total aqueous outflow resistance, but the outflow capacity differs greatly over the segments of the eye. Morphological and functional assessment of the intrascleral outflow tract is challenging, due to its deep scleral location and the complex nature of its small diameter vessel network. In this review, we present novel insights into its morphology and function, based on advances in a variety of imaging modalities, including optical coherence tomography, fluorescence imaging and electron microscopy. Together with clinical data, they support the paradigm of significant sectorial differences in aqueous outflow, which has a direct impact on glaucoma surgery targeting sectors of the trabecular meshwork, such as trabeculectomy ab interno or trabecular meshwork bypass stents. Possible future applications of intrascleral outflow tract imaging are discussed. Georg Thieme Verlag KG Stuttgart · New York.