Neuroprotection With Phenytoin in Optic Neuritis

Optic neuritis is caused by inflammation of the optic nerve and causes loss of vision in the affected eye. It is often associated with multiple sclerosis. Loss of vision after an attack of optic neuritis is caused by damage to the nerve fibres in the optic nerve. There are a number of factors that contribute to nerve fibre damage including increased levels of sodium within them, so blocking sodium entry could help to protect them against damage. The purpose of this study is determine whether phenytoin (which blocks sodium entry into cells) can protect against loss of nerve fibres and prevent loss of vision after optic neuritis.