AQP4 and cancer-associated retinopathy: Although rare, thymoma associated with visual symptoms has been reported in association with paraneoplastic autoantibodies, such as cancer-associated retinopathy (CAR) with anti-retinal antibodies, paraneoplastic optic neuropathy (PON) with anti-CRMP5 antibody, or NMO with AQP4-IgG [2].