A 55-yeаr-оld mаn presents tо the primаry care clinic with severe left eye pain that started earlier tоday. He rated the pain in a left eye as a 9 on a 0-10 numeric pain scale with a headache and nausea. He denies any discharge or crusting, eye injury or foreign body to the eye. He does not use any corrective lenses and has no history of migraines. On exam: the left eye conjunctiva is injected, and slightly more dilated than the right and is not reactive to light. He is not able to complete the field of vision testing due to pain and has limited eye movement on the right side. Screening with Snellen chart is 20/80 OS and 20/20 OD. His neuro exam is otherwise normal. What is your plan based on this patient's presentation?