The eyes of 15 autopsied patients with multiple myeloma were studied histologically. Twelve showed intraocular lesions. Five of the 15 cases had multiple pars plana cysts, seven of 11 had retinal capillary microaneurysms, and two had plasma cell lesions. The plasma cell lesions were a choroidal infitrate in a patient with plasma cell leukemia and a small, solitary plasmacytoma of the ciliary body in a patient with a similar lesion in the kidney. The multiple pars plana cysts were filled with proteinaceous material. They probably formed by splitting of the ciliary epithelium and accumulation of an abnormal blood protein. As yet, they have not been seen in the living patient. However, they are thought to be pathologically characteristic of multiple myeloma. Retinal capillary microaneurysms similar histologically to those seen in diabetes mellitus were found in the midperipheral retina. They did not bind fluorescent antihuman γ-globulin. A mutual exclusion of the pars plana cysts and the retinal microaneurysms were noted.
Sanders TE, Podos SM, Rosenbaum LJ. Intraocular Manifestations of Multiple Myeloma. Arch Ophthalmol. 1967;77(6):789-794. doi:10.1001/archopht.1967.00980020791015