FIGURE 2.

All ocular sites tested for experimental NGF delivery are summarized as follows: (1) the topical administration (eye drop instillation and emulsion/gel application) (green labeled), (2) the intravitreal injections (ophthalmic solutions/suspentions, implants, and nanotecnology), and (3) the periocular administration (implants or injections) at the posterior segment. The periocular route includes the subconjunctival, subtenon, peribulbar, and retrobulbar sites of injection. Except for the systemic route, all the others have been tested for NGF and anti-NGF at both experimental and clinical levels. The topical administration is actually a routine procedure for specific eye disorders. Highlighted in red: our future directions on experimental animals, comprising the anti-VEGF/NGF combined intravitreal injection or the use of NGF nanoparticles layered in the vitreal chamber. The table summarizes the different routes of NGF administration in the eye, in an experimental model and human beings.