Impact of nitric oxide's bidirectional role on glaucoma: focus on Helicobacter pylori-related nitrosative stress

Nitric oxide (NO), a small molecule generated ubiquitously, targets a plethora of tissues to regulate both physiological and pathophysiological functions. NO overproduction, stimulated by microenvironmental conditions, is the main component that dysregulates the tight balance between its beneficial and damaging roles in ocular homeostasis. Considering the protective functions of NO against glaucoma, its endogenous release facilitates aqueous humor drainage and regulates ocular blood flow, maintaining a normal intraocular pressure. NO overproduction generates free radicals, such as peroxynitrite, which induce a vicious circle of vascular disharmony and dysregulation, transient ischemia, nitrosative stress, neuronal degeneration, and permanent glaucomatic injury. Helicobacter pylori (Hp) is considered a burdening factor of glaucoma. NO overproduction and possible systematic dispersion in Hp infection (Hp-I) could suggest a potential pathophysiological bridge between these conditions. In this review, we aim to elucidate the role of NO in glaucoma with respect to Hp-I, with the aim to stimulate further studies.