CC: 60 y.o. man who was evaluated 1 wk ago for ?conjunctivitis? OS by internal medicine. HPI: Patient complained of a painless, gradual redness of his left eye over the last several months. He does not report any pain, discharge, discomfort, or itching. He presented to the on-call ophthalmologist for evaluation. He pointed to some fullness of the superior aspect of the medial canthus OS with mild conjunctival injection. Pt also complained that things were "blurry" with a slight double image, which resolved when one eye was closed separately. PMH: h/o non-Hodkin's lymphoma and in remission for numerous years. No other ocular history or medical problems. No h/o of ocular traumas or sugeries. EXAM Best corrected visual acuities: 20/20 OU. Pupils: 4.5->3.5, no RAPD EOM: elevation deficit OS with left hypotropia in primary gaze; VF Full to FC OU IOP: 18 mmHg OD, 19 mmHg OS DFE: retina exam notable for normal macula, vessels, and periphery OU. Optic nerves, normal. SLE: OD normal, OS see photos below. Hertel (base 113): 13 mm OD and 17 mm OS EOM: Note the left hypotropia in primary gaze and elevation deficit OS with upgaze. Left eye with superior conjunctival injection. Left medial canthus with fullness. Note the asymmetric ptosis OS (more ptosis medially). Feel free to discuss the following: What tests should you order (I'll post labs when asked for them)? What's the differential diagnosis? What's the diagnosis? What is the treatment of choice, surgically and/or medically?