The neuroprotective effect of NGF has also been studied in various neurodegenerative diseases of the eye.12 Phase 1/2 and pilot clinical trials have used NGF eye‐drops in an attempt to rescue or reduce the degeneration of retinal neuronal or ganglion cells in retinitis pigmentosa and glaucoma patients.12, 13, 14 In addition, patients with DR have increased NGF concentration in the vitreous, as compared to non‐diabetic individuals.4 This evidence concerns the gene NGF and retinitis pigmentosa.