In this respect, it has been reported that a single intravitreal injection of a nanoformulation of glial cell derived neurotrophic factor was effective in providing the sustained release of the drug in a model of glaucoma, which resulted in protection from cell death of retinal ganglion cells up to 11 weeks after the injection (Checa-Casalengua et al., 2011). The gene discussed is GDNF; the disease is glaucoma.