Unilateral cancer-associated retinopathy: diagnosis, serology and treatment.

Purpose: To report a case of unilateral cancer-associated retinopathy (CAR) with clinical, serological and electroretinogram (ERG) normalization after aggressive cancer treatment combined with steroids and rituximab.

Methods: Work-up included extensive clinical and electrophysiological testing. Also, serological work-up for antiretinal antibodies and oncological screening was organized.

Results: A 45-year-old female presented with progressive photopsias, photophobia and relative central scotoma in the right eye since 6 weeks prior. BCVA was 1.0 in both eyes. Biomicroscopy, IOP and fundus exam were unremarkable. Also, colour vision, autofluorescence imaging, OCT and EOG were normal. Visual fields showed decreased central sensitivity in the right eye. ERG showed a unilateral, electronegative combined and ON-bipolar response. A diagnosis of CAR was suspected. After a diagnosis of an adenocarcinoma of the right ovary, radical ovariectomy and hysterectomy were performed, followed by adjuvant chemotherapy. A whole-body PET scan revealed no metastasis. Treatment with rituximab monoclonal antibodies in combination with corticosteroids was initiated. The patient tested positive for serum autoantibodies against TRPM1, a transient receptor potential cation channel expressed in ON-bipolar cells. During treatment, there was progressive improvement in symptoms and the ERG normalized. Serology confirmed complete clearance of autoantibodies.

Conclusions: Although rare, unilateral CAR does occur and in cases with high clinical suspicion an oncological work-up is mandatory. Aggressive cancer treatment combined with steroids and rituximab can lead to normalization of the clinical and ERG phenotype, with clearing of antiretinal antibodies.