Life under pressure: The role of ocular cribriform cells in preventing glaucoma

Abstract

Primary open-angle glaucoma is a multifactorial blinding disease often impacting the two pressure-sensitive regions of the eye: the conventional outflow pathway and the optic nerve head (ONH). The connective tissues that span these two openings in the globe are the trabecular meshwork of the conventional outflow pathway and the lamina cribrosa of the ONH. Resident cribiform cells of these two regions are responsible for actively remodeling and maintaining their connective tissues. In glaucoma, aberrant maintenance of the juxtacanalicular tissues (JCT) of the conventional outflow pathway results in ocular hypertension and pathological remodeling of the lamina cribrosa results in ONH cupping, damaging retinal ganglion cell axons. Interestingly, cells cultured from the lamina cribrosa and the JCT of the trabecular meshwork have similarities regarding gene expression, protein production, plus cellular responses to growth factors and mechanical stimuli. This review compares and contrasts the current knowledge of these two cell types, whose health is critical for protecting the eye from glaucomatous changes. In response to pressure gradients across their respective cribiform tissues, the goal is to better understand and differentiate healthy from pathological behavior of these two cell types.

Keywords: Astrocyte; Juxtacanalicular tissue; Lamina cribrosa; Primary open-angle glaucoma; Schlemm's canal; Trabecular meshwork.

Figure 1. Schematic showing human eye in cross section, highlighting the two cribiform regions

In the posterior eye, the lamina cribrosa, its structure and resident cells are depicted (blood vessels are not shown for simplicity). In the anterior eye, the conventional outflow pathway is shown, zooming in on the juxtacanalicular region of the trabecular meshwork where juxtacanalicular cells reside.