A 67-year-old man presented to the ophthalmology clinic with a 1-year history of swelling in both eyes and protrusion of the right eye (Panel A) and a 2-week history of blurry vision. Extraocular movements were limited, and visual acuity was reduced in both eyes. There was no swelling in the parotid or submandibular glands. The results of laboratory tests were notable for a serum IgG4 level of 1440 mg per deciliter (reference range, 3 to 201) and an absolute eosinophil count of 769 cells per cubic millimeter (reference range, 10–24). Magnetic resonance imaging of the orbits showed swelling of the lacrimal glands (Panel B, arrows) and the lateral rectus muscles (arrowheads) on both sides. There were also mass lesions surrounding the optic nerves (Panel B, asterisks). A biopsy specimen of the right lacrimal gland showed a lymphoplasmacytic infiltrate, with IgG4-positive plasma cells. Neither storiform fibrosis nor obliterative phlebitis was present. A diagnosis of IgG4-related dacryoadenitis, orbital myositis, and optic-nerve disease was made. Computed tomography of the whole body did not reveal other sites of involvement. Treatment was initiated with 30 mg of prednisone daily, which was subsequently tapered. At a 3-month follow-up visit, the patient’s symptoms had abated.