Paraneoplastic retinopathy and optic neuropathy

: Paraneoplastic retinopathy including cancer-associated retinopathy (CAR) and melanoma-associated retinopathy (MAR), and paraneoplastic optic neuropathy (PON) are visual disorders associated with systemic cancer. Patients with CAR typically present with progressive loss of vision and photopsia, which are related to dysfunction of both cones and rods in photoreceptors. The triad of photosensitivity, ring scotoma, and a reduced caliber of the retinal arteriole along with undetectable signals in electroretinogram (ERG) are specific manifestations of CAR. CAR is associated most commonly with small-cell lung cancer (SCLC) and occasionally with gynecologic tumors, and it is usually caused by autoantibodies against recovering, which is a calcium-binding photoreceptor protein that participates in the transduction of light. MAR is characterized by shimmering, flickering, or pulsating photopsias, and usually occurs in the patients with a cutaneous melanoma. MAR differs from CAR in terms of visual acuity and color vision and is associated with a characteristic pattern detected in ERG. Autoantibodies against the bipolar cells of the retina have been identified in patients with MAR. Patients with PON frequently present with progressive visual loss and optic disc edema, or with other paneoplastic neurologic syndromes related to SCLC, such as paraneoplastic encephalomyelitis or retinitis, ophthalmoplegia, and subacute cerebellar syndrome. Autoantibodies against collapsin-responsive mediator protein-5 (CRMP-5, also called anti-CV2) are considered to be as the causative factor. Treatments with corticosteroids, plasma exchange, and intravenous immune globulin as well as treatment of the tumor itself, occasionally improves these paraneoplastic visual syndromes. However, the prognosis depends on their underlying malignancy.