Effect of Citicoline/Homotaurine on PERG in Primary Open Angle Glaucoma

Inclusion Criteria: * age between 40 and 75 years; * diagnosis of primary OAG (POAG) from, at least, 3 years; * visual acuity \> 0.7 (7/10) decimals; * refractive error \< 5 D (spheric) and \< 2D (toric); * transparent diopter means (cornea and lens); * controlled IOP (\<18 mmHg, morning value) with beta-blockers and prostaglandin analogues as monotherapy or as associative therapy (fixed or unfixed); * stable IOP\<18 mmHg in the last 2 years; * stable and unchanged topical therapy in the last 6 months; * stable disease in the last 2 years (no more than -1 dB/year at MD of visual field); * at least two reliable visual fields (Humphrey 24-2 Swedish interactive threshold algorithm -SITA- Standard) per year in the last 2 years; * early to moderate visual field defect (MD \<12 dB); * electrophysiological (PERG) parameters alterations similar to glaucomatous pathology; * written consent to participate to study procedures and data utilization in an anonymous form Exclusion Criteria: * ocular hypertension with normal optic nerve and visual field; angle closure glaucoma; * congenital glaucoma; secondary glaucoma; normal tension glaucoma; * history of recurrent uveitis/scleritis/herpes infection; * pregnancy and breastfeeding; * contraindication to Citicoline and/or Homotaurine * contraindication to beta-blockers and prostaglandine analogues * topical therapy with Brimonidine monotherapy or fixed combination (with timolol or brinzolamide) * topical therapy with pilocarpine and aceclidine, monotherapy or fixed combination systemic or topical treatment with another neuroprotective agent in the last 4 months prior to enrollment * systemic therapies affecting patients' performance in visual field examination (sedatives); * glaucomatous scotomas within 10 degree from fixation * any condition limiting the patient's ability to participate in the study; * other ocular causes of visual field and PERG changes, such as cataract, myopic chorioretinopathy, macular diseases, retinal vascular occlusion, diabetic retinopathy; * other systemic causes of visual field and PERG changes such as neurodegenerative disorders (Alzheimer's disease, Parkinson's disease, ALS, MS) or pituitary disorders; * cerebral ischemia in the last 2 years * any change in topical therapy in the 6 months prior to enrollment or during the study period concomitant participation to another clinical trial * any previous filtering and/or retinal surgery; * cataract surgery in the last 6 months; * any previous laser treatment for glaucoma in the last 5 years