Anthony is a 21 year old art student who presents with a one day history of red eyes with severe discharge and gritty/foreign body sensation. He denies any significant pain, visual disturbance or trauma to his eyes. Systems review is grossly unremarkable except describing vague urinary symptoms. He has no significant personal or family history. He smokes ten cigarettes-a-day (has declined smoking cessation referral) and drinks 14-21units of alcohol a week. Examination is notable for bilateral conjunctival injection and mucopurulent discharge. Eye movements are normal and visual acuity is 6/6. Anthony also has tender pre-auricular lymph nodes.
Based on the likely diagnosis, what is the most appropriate treatment?