NOS1 and myopia: Nevertheless it is not easy to interpret these results given the ambivalent role of nitric oxide as a neurodegenerative/neuroprotective agent (Contestabile et al., 2003; Pannu and Singh, 2006), and it is even more complicated due to the different isoforms of NOS that might be differently involved in retina and choroid neovascularization (Ando et al., 2002), or in ocular growth of several animal models of myopia (Nickla et al., 2006).