Progressive Unilateral Vision Loss

Choroidal hemorrhage in the left orbit with retinal detachment: your dx?

A 16-year-old African American boy had progressive loss of vision in the left eye over 2 weeks. He also had pain around the left orbit with some radiation to the temple. One side of his face appeared to be more flushed when he exerted himself. He had no seizures or hemiparesis and was cognitively intact. An ultrasonogram of the orbit revealed choroidal hemorrhage in the left orbit with overlying retinal detachment. The patient's MRI scan is shown.

What's your diagnosis?