Mrs Jones is a 29 year old who has booked an emergency appointment today as she is worried about her left eye. Yesterday, whilst changing her daughter’s nappy she thinks she might have scratched her eye. Since then her eye has been sore and teary and today she has noticed it is red. Her other eye is not affected and her vision is normal. Mrs Jones is otherwise fit and well, she a non-smoker and does not drink alcohol. Examination is notable for conjunctival injection. You insert fluorescein drops which reveals a single linear area of uptake with cobalt blue light. You evert the eyelid and there is no evidence of a foreign body. Visual acuity is intact and there is no peri-orbital swelling. Observations including temperature, heart rate, respiratory rate and blood pressure are normal.
Given the most likely cause of Mrs Jones’ symptoms what is the most appropriate treatment?