Endogenous endophthalmitis was suspected. A diagnostic vitrectomy was performed, and vancomycin hydrochloride, ceftazidime, and clindamycin phosphate were injected intravitreously. Vitreous cultures and polymerase chain reaction of vitreous washings for cytomegalovirus, herpes zoster virus, Candida, and Toxoplasma were negative. Tuberculin purified protein derivative and blood cultures were negative. Results from complete blood cell count, comprehensive metabolic panel, rapid plasma reagin, fluorescent treponemal antibody absorption, Toxoplasma serology, human immunodeficiency virus testing, angiotensin-converting enzyme level, serum lysozyme level, and urinalysis were normal, except for elevated serum and urine glucose levels. Postoperatively, best-corrected visual acuity was counting fingers OS. The macular lesion was soon less apparent and continued to fade postoperatively. Systemic workup to this point was unfruitful. Computed tomography of the chest showed only nonspecific lower-lobe scarring in the right lung.