A 65 year old man presents to the emergency department with a severely painful right eye. He has no previous history of ocular problems.

The pain came on that evening and became progressively worse. When you get to see him he is in severe pain and is vomiting profusely and complaining of a severe frontal headache.

His visual acuity (corrected) is 6/60 in the right eye and 6/9 in the left.

Have a look at the appearance on the slit lamp and then consider the questions.