NOS3 and age-related macular degeneration: Bhutto et al. studied the localization of NOS isoforms in 22 human donor eyes with AMD (both non-neovascular and nAMD) by immunohistochemistry and compared their distribution to that observed in age-matched controls; they detected a significant decrease in nNOS and eNOS in the retina and choroid of AMD patients and postulated that reduced concentrations of NO may be associated with vasoconstriction and blood flow decrease (secondary to the loss of CC and perivascular nerve fibers) in the submacular choroid in AMD [177].