The pathophysiology of primary open-angle glaucoma (POAG) remains unclear, with potentially a multifactorial etiology. Intraocular pressure (IOP) is the only known modifiable risk factor, yet two clinical conundrums remain - patients with elevated IOP who do not develop glaucoma (ocular hypertension, OHTN) as well as patients with IOP <21 mmHg who still develop glaucoma (normal tension glaucoma, NTG). The etiology of these two scenarios remains unclear.