Jade is a 46 year old baker who presents with a one day history of a red painful left eye and photophobia. She has had conjunctivitis twice in the last year which responded to Chloramphenicol. Past medical history includes Rheumatoid arthritis which is well controlled on Methotrexate.
On examination there is left conjunctival injection, normal eye movements and a crop of vesicles seen on her left upper eyelid. Visual acuity is intact.
What is the most likely diagnosis?