Central retinal vein occlusion in two patients with immunoglobulin G multiple myeloma associated with blood hyperviscosity.

A 69-year-old man (Patient 1) complained of anorexia, lumbago, and seeing floaters OS. The results of laboratory tests showed immunoglobulin (Ig) G lambda-type multiple myeloma associated with blood hyperviscosity. Retinal hemorrhages OD and central retinal vein occlusion OS were found. A 71-year-old woman (Patient 2) with IgG kappa-type multiple myeloma had blood hyperviscosity. Retinal microaneurysms OD and central retinal vein occlusion OS were found. We believe that our patients represent rare cases of IgG multiple myeloma associated with blood hyperviscosity and central retinal vein occlusion.