Paraneoplastic retinopathies

Clinical features
The paraneoplastic retinopathies include two well characterized syndromes. Cancer-associated retinopathy is almost always associated with small-cell lung carcinoma. Symptoms usually present bilaterally and reflect the simultaneous dysfunction of both cones and rods. Patients complain of photosensitivity, reduced visual acuity, decreased color perception, ring scotomas, nyctalopia, and prolonged dark adaptation. Ophthalmoscopy examination typically shows attenuated arterioles and electroretinogram discloses flat or severely attenuated photic and scotopic responses.

Melanoma-associated retinopathy usually occur after the diagnosis of malignant melanoma often at the stage of metastases. Patients with this syndrome usually have near normal visual acuity and color vision but develop sudden shimmering, flickering photopsias, night blidness, and mild peripheral visual field loss. Symptoms are explained by dysfunction of rods whereas cones are not affected. Typical findings in electroretinograms include a markedly reduced or absent dark-adapted b-wave along with a slightly attenuated a-wave to scotopic stimulus.

Associated antibodies
Most of the patients with cancer-associated retinopathy present anti-recoverin antibodies. Other antibodies detected in this syndrome are anti-enolase antibodies, antibodies to TULIP-1 (tubby-like protein 1), and antibodies against the photoreceptor cell-specific nuclear receptor. Melanoma-associated retinopathy patients usually harbor anti-rod bipolar cell antibodies.

Treatment
As in other paraneoplastic neurological syndromes associated with neuronal damage, paraneoplastic retinopathy rarely improves. The best chance to at least stabilize the syndrome is to induce a complete response of the tumor. Immunotherapy rarely is effective but steroids or intravenous immunoglobulins have partially improved the visual symptoms in a few patients.

Selected references
1. Chan JW. Paraneoplastic retinopathies and optic neuropaties. Surv Ophthalmol 2003;48:12-38.
2. Jacobson DM, Thirkill CE, Tipping SJ. A clinical triad to diagnose paraneoplastic retinopathy. Ann Neurol 1990;28:162-7.

3. Millan AH, Saari JC, Jacobson SG, et al. Autoantibodies against retinal bipolar cells in cutaneous melanoma-associated retinopathy. Invest Opthalmol Vis Sci 1993;34:91-100.
4. Weinstein JM, Kelman SE, Bresnick GH, et al. Paraneoplastic retinopathy associated with antiretinal bipolar cell antibodies in cutaneous malignant melanoma. Ophthalmology 1994;101:1236-43.

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