Efficacy and Safety of Oral Valproic Acid for Retinitis Pigmentosa

Inclusion Criteria: * Diagnosis of retinitis pigmentosa (RP) established by night blindness, visual field constriction, marked reduction of electroretinogram, and the clinical signs of RP in fundus examination * Best corrected visual acuity of 20/200 or more on a Snellen chart in at least one eye * Intact visual field of 5 or more as measured by the kinetic perimetry * Understand and sign the IRB-approved informed consent document for the study * Body weight: male (40 kg to 100 kg), female (40 kg to 80 kg) * Must be able to swallow tablets * Female subjects of childbearing potential must commit to practice acceptable methods of contraception Exclusion Criteria: * Pregnant women * Lactating mothers * Medical problems that make consistent follow-up over the treatment period unlikely (e.g., stroke, myocardiac infarction, malignancy) or severe systemic disease * Other ocular disease: retinal disease other than RP or cystoid macular edema, glaucoma, cataract worse than +2PSC or infectious corneal disease * Coagulation disorder or bleeding-tendency * Liver dysfunction * Renal dysfunction * History of pancreatitis * History of neurological disorders including epilepsy, history of brain injury or any organic brain disorders * History of mental disorders including schizophrenia, bipolar disorder, or suicidality * Currently receiving valproic acid or other anti-convulsants * Has taken one of the following drugs at least 4 weeks prior to enrollment as these drugs are specifically known to affect the progression of RP: vitamin A, lutein, omega-3 fatty acid, or any antioxidant which affect the blood flow of retina or retinal function.