Multiple myeloma is a neoplastic plasma-cell disorder resulting from malignant 
plasma cells in the bone marrow. It can cause a hyperviscosity syndrome 
secondary to the paraproteinaemia associated with the disease. The increased 
hyperviscosity can lead to retinal vein occlusions and other ocular problems 
that may challenge clinicians. In patients with multiple myeloma and 
hypertension and/or diabetes mellitus, retinal changes appear similar and 
changes due to one disease or the other may be difficult to determine. A 
48-year-old white female presented to the clinic with a complaint of blurry 
vision in her left eye. A full comprehensive ocular examination revealed a 
central retinal vein occlusion presumably from the patient's history of 
hypertension, diabetes mellitus and hypercholesterolaemia. Further bloodwork 
revealed monoclonal protein in the patient's serum and an increased percentage 
of plasma cells in the bone marrow. She was diagnosed with monoclonal gammopathy 
of undetermined significance, part of the multiple myeloma disease spectrum. She 
was referred to a retinal specialist for initiation of intravitreal injections 
of anti-vascular endothelial growth factor. Multiple myeloma has been implicated 
in younger patients as an underlying cause of retinal vein occlusions. Multiple 
myeloma should be considered as a differential diagnosis in young patients with 
retinal vein occlusions, even if other risk factors for venous occlusion like 
hypertension, diabetes mellitus and hypercholesterolaemia are present. Timely 
referral to the patient's primary care physician and haematologist is important 
for appropriate treatment and control of underlying systemic conditions.