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Cancer associated retinopathy (CAR) is a paraneoplastic disease of the eye associated with the presence of extraocular malignancy and circulating autoantibodies against retinal proteins.
ORPHA:71505Classification level: Disorder
- CAR syndrome
- Paraneoplastic retinopathy
- Prevalence: Unknown
- Inheritance: Not applicable
- Age of onset: Adult
- ICD-10: -
- OMIM: -
- UMLS: C0730307 C1321315
- MeSH: -
- GARD: -
- MedDRA: -
The prevalence is unknown but around 100 cases have been reported in the literature.
CAR is a subacute, progressive autoimmune retinopathy that induces visual loss and visual symptoms that often manifest before diagnosis of cancer. The most common malignancies related to CAR are carcinomas including small cell carcinoma of the lung, non-small cell carcinoma, and endometrial, ovarian, cervical, breast, prostate, and colon carcinomas. Clinically, photosensitivity, deterioration of visual acuity and visual field changes (scotoma, or central constriction), attenuated retinal arteriole, in addition to the presence of serum autoantibodies against retinal proteins, are crucial for diagnosis. The electroretinogram (ERG) typically shows marked reduction or loss of rod and cone-mediated responses. Patients with anti-recoverin retinopathy present with symptoms of night blindness, photopsias, loss of peripheral or pericentral visual field, reduced central acuity, and major abnormalities involving both the rod and cone system, indicating widespread retinal dysfunction. Patients with anti-enolase retinopathy experience varying degrees of central or pericentral visual field loss, shimmering photopsias, loss of color vision, reduced vision in bright light, and, less commonly, night blindness. Pathology, when available, shows retinal degeneration with the loss of rods and cones and the outer nuclear layer.
The exact etiology remains unknown but an autoimmune mechanism may contribute to the development of retinal degeneration. No known genetic association has been reported.
The diagnostic evaluation should include electroretinography (ERG) in patients with unexplained visual glare and subacute visual loss, screening for anti-retinal antibodies associated, in particular, with anti-recoverin (23-kDa protein) and anti-alpha-enolase (46-kDa) antibodies and screening for systemic cancer.
The main differential diagnosis is autoimmune retinopathy. Paraneoplastic patients are usually older than patients with autoimmune retinopathy at the onset of visual symptoms. Symptoms of paraneoplastic retinopathy may precede recognition of systemic malignancy by several months.
Management and treatment
There is no established protocol for the treatment of autoimmune retinopathy. Treatment for CAR involves modulation of the immune system to reduce the autoimmune response.
The ophthalmological prognosis varies depending on the clinical course of CAR, ranging from progressive visual loss to blindness. The overall prognosis varies depending on the type of cancer present.