Ocular Surface Disease

Could use of nitric oxide be a potential breakthrough in ophthalmology?

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Nitric oxide (NO) holds promise in the field of ophthalmology due to its diverse biological effects making it a key player in regulating ocular inflammation, aiding in ocular surface wound healing, controlling intraocular pressure in glaucoma, alleviating retinal diseases, and potentially suppressing myopia progression, according to a narrative review.

Although challenges remain regarding the stability of gaseous NO, the development of novel NO donors and effective delivery platforms could greatly expand its role in ophthalmic care, the study authors suggested.Bottom of Form

NO, a molecule synthesized within the human body, plays a pivotal role in ocular health. It is generated by nitric oxide synthase (NOS) from L-arginine, or through the enzyme-dependent reduction of dietary nitrate.

The eye hosts 3 types of NOS (eNOS, nNOS, and iNOS) that exhibit abundant expression, both under normal physiological conditions and in response to pathologic factors, according to the study, which establishes that the biological effects of NO are dose-dependent.

Low intraocular concentrations, produced by eNOS or nNOS, contribute to vasodilation, intraocular pressure regulation, and neuroprotection. Heightened levels of iNOS, typically observed in ocular diseases such as glaucoma and retinal ischemic or degenerative conditions, can lead to tissue inflammation, ocular cell apoptosis, and neurodegeneration.

Notably, NO emerges as a versatile agent in ocular injury management. It facilitates the healing of ocular surface wounds and demonstrates efficacy in eradicating pathogens, including bacteria and Acanthamoeba, in cases of chemical burns or infectious keratitis. Additionally, NO exhibits antifibrotic properties through the cyclic guanosine monophosphate (cGMP) signaling pathway, and its ability to induce smooth muscle relaxation holds promise in inhibiting myopia progression in children.

The authors concluded that NO could play a central role in regulating ocular inflammation across a spectrum of ocular conditions.

Lee S, Park CY. Nitric oxide: an old drug but with new horizons in ophthalmology-a narrative review. Ann Transl Med. 2023;11(10):352. doi: 10.21037/atm-22-5634. Epub 2023 Jun 6. PMID: 37675299; PMCID: PMC10477639.

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