Cilioretinal Artery Occlusion - Nasal (not macular)

77 year old female There is a shadow in the top half of her temporal vision in the left eye that came on suddenly yesterday morning.  It has not changed since then and the right eye is OK.  She has had sinus headaches.  She had no focal neurological changes.  
VA OD: Dcc20/32
VA OS: Dcc20/16-1
IOP: TP: OD:18 OS:19