Does eNOS Gene Polymorphism Play a Role in the Maintenance of Basal Vascular Tone in the Choroid or Optic Nerve Head?

Nitric oxide (NO) is a potent endothelium-derived vasodilatator that plays a major role in the control of ocular blood flow. Endothelial NO synthase (eNOS) is one of three isoforms of NOS producing NO through hydroxylation of L-arginine. The eNOS gene is located on the long arm of chromosome 7, and different polymorphic variations have been identified. These single nucleotide polymorphisms (sNP´s) have the ability to change transcription activity and therefore enzyme levels. Recent data indicate that the T -786C polymorphism (especially the homozygous variant) is associated with reduced eNOS activity and consequently impaired NO production. In the present study the investigators want to investigate if the T -786C eNOS gene polymorphism determines choroidal and optic nerve head blood flow.