The patient was an 82-year-old man with diabetes, hypertension, and lung cancer diagnosed two weeks previously who presented with a complaint of a sudden, recent onset of a shadow in the nasal visual field in the right eye associated with new floaters and blurriness. The visual acuity was 20/40 OD and 20/30 OS. The anterior chamber examination was remarkable for pseudophakia without posterior capsular opacity. The posterior chamber examination revealed 2+ vitreous cells in the right eye and a clear vitreous in the left eye. The optic nerves looked healthy. Both maculas had RPE disturbances, a few drusen, and rare hemorrhages. A montage of the fundus periphery of the right eye can be viewed, and the periphery of the left eye is unremarkable except for a few scattered hemorrhages. What is the most likely diagnosis? Is any treatment needed?