Excerpt from Cancer Associated and Related Autoimmune Retinopathies
Synonyms, Key Words, and Related Terms: cancer associated retinopathy, CAR, melanoma associated retinopathy, MAR, autoimmune retinopathy, AR, paraneoplastic retinopathy, PR, autoimmune-related retinopathy and optic neuropathy, ARRON, cancer associated cone dysfunction, acute zonal occult outer retinopathy, AZOOR, vision loss, recoverin-associated retinopathy, RAR
Cancer- and autoimmunity-associated retinopathies belong to a spectrum of uncommon ophthalmic disorders in which autoantibodies directed at various retinal components cause progressive vision loss. In most cases, an evaluation reveals an underlying malignancy, placing this condition in the category of paraneoplastic syndromes. In rare cases, no such malignancy is found, and patients are considered to have autoimmune retinopathy (AR), which is also termed recoverin-associated retinopathy (RAR). In some cases, patients with an underlying malignancy have been found to have high titers of antiretinal antibodies but no evidence of visual loss. The clinical features of paraneoplastic retinopathy (PR) and AR are generally similar. Specific forms of PR that have been identified include cancer-associated retinopathy (CAR), melanoma associated retinopathy (MAR), and cancer-associated cone dysfunction. Paraneoplastic syndromes involving the optic nerves are less common than those involving the retina. The best-defined of these paraneoplastic syndromes is associated with collapsin response-mediator protein-5 (CRMP-5)-immunoglobulin G (IgG) and manifests as bilateral optic neuritis with retinitis and vitritis.
Patients with PR and AR typically present with rapid, painless vision loss associated with photopsias and photosensitivity. Symptoms are usually bilateral, occasionally sequential, and progressive over weeks to months. Findings on retinal examination may be normal early in the course of the disease, posing a diagnostic challenge in some cases. Markedly abnormal electroretinographic (ERG) findings indicate the correct diagnosis, which can usually be confirmed with immunofluorescence techniques to identify circulating retinal antibodies. In most cases of CAR, vision loss occurs before malignancy is diagnosed. In contrast, vision loss due to MAR usually occurs in patients whose melanoma is already diagnosed, often at the stage of metastatic spread. In an excellent review, Keltner et al summarize the clinical and immunologic findings in 11 new patients with MAR and 51 reported in the literature.1 Chan reviewed all PRs and optic neuropathies.2
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