Intravitreal dexamethasone implant use as first-line therapy for cancer-associated retinopathy

We present a 65-year-old female smoker who presented with acute bilateral blurred vision. Investigations led to an endobronchial ultrasound-guided fine-needle aspiration resulting in an early diagnosis of limited stage small cell lung cancer. Positive recoverin antibodies supported the diagnosis of cancer-associated retinopathy (CAR). CAR was the first manifestation of systemic malignancy in our patient and early diagnosis enabled curative intent systemic treatment with chemotherapy and radiotherapy. Ocular-specific treatment is required in CAR, although no standardised treatment exists. Current treatment options include steroids and immunosuppressive agents. Our patient was administered bilateral intravitreal dexamethasone implants, resulting in significant visual field and electroretinogram improvement at 8 weeks post-intervention. To our knowledge, this represents the first reported successful use of intravitreal dexamethasone implants as first-line therapy, in conjunction with chemoradiotherapy. Intravitreal dexamethasone implants therefore may provide an effective and safe treatment for CAR by reducing intraocular inflammation without systemic effects.

Electroretinographic Findings in Melanoma-Associated Retinopathy Treated by Intravitreal Dexamethasone Implant

A 63-year-old male with a history of bladder cancer in remission presented with progressive vision loss during a period of 2 years. Slit-lamp and funduscopic examination were unremarkable. Electroretinogram (ERG) revealed an unrecordable scotopic response and a moderately decreased photopic response. Computed tomography of the chest, abdomen, and pelvis showed a new duodenal mass. Subsequent biopsy disclosed malignant melanoma, and a diagnosis of melanoma-associated retinopathy (MAR) was made. The patient was then treated with a dexamethasone intravitreal implant 0.7 mg in his left eye. Two months after the implant, the patient reported a mild symptomatic improvement in his left eye, and ERG testing performed after the implant insertion revealed partial improvement in several scotopic and photopic ERG parameters. Repeat spectral-domain optical coherence tomography disclosed an improvement in retinal thickening. To the best of the authors' knowledge, this is the first report illustrating potential subjective visual improvement, improvement in retinal thickening, and ERG changes following treatment by intravitreal dexamethasone implant for MAR. [Ophthalmic Surg Lasers Imaging Retina. 2021;52:454-456.].

The Enigma of CRB1 and CRB1 Retinopathies

Mutations in the gene Crumbs homolog 1 (CRB1) are responsible for several retinopathies that are diverse in severity and phenotype. Thus, there is considerable incentive to determine how disruption of this gene causes disease. Progress on this front will aid in developing molecular diagnostics that can predict disease severity with the ultimate goal of developing therapies for CRB1 retinopathies via gene replacement. The purpose of this review is to summarize what is known regarding CRB1 and highlights information outstanding. Doing so will provide a framework toward a thorough understanding of CRB1 at the molecular and protein level with the ultimate goal of deciphering how it contributes to the disease.

Non-Paraneoplastic Autoimmune Retinopathy: The First Case Report in Korea

Autoimmune retinopathy (AIR) is an immune-mediated retinopathy, resulting from an immunologic process caused by the aberrant recognition of retinal antigens as autoantigens. The diagnosis of AIR involves the detection of antiretinal antibodies with concurrent clinical and electrophysiological evidence of retinopathy. A 40-year-old patient presented with progressive loss of bilateral vision over several months. A fundus examination was unremarkable. Spectral domain optical coherence tomography revealed a blurred photoreceptor ellipsoid zone at the subfoveal region in both eyes with more prominent disruption in the left eye. Full-field electroretinography (ERG) showed relatively normal rod and cone responses in the right eye, and decreased photopic bwaves with minimal attenuation of a-waves in the left eye. Multifocal ERG demonstrated slightly reduced amplitude of the inner segment ring in the right eye and decreased amplitudes and delayed latencies of all modalities in the left eye. The patient was suspected to have AIR and it was supported by positive Western blots for 23-kDa protein, enolase (46-kDa), aldolase (40-kDa), 62-kDa and 78-kDa proteins and by immunohistochemical staining of human retinal bipolar and ganglion cells. Despite the immunosuppressive treatment, the destruction of the retinal photoreceptors progressed, and immunosuppressive interventions produced very little visual improvement. We report on what is, to the best of our knowledge, the very first case of serologically confirmed nonparaneoplastic AIR in Korea.

[Paraneoplastic retinopathy]

Paraneoplastic retinopathy (PR) mainly includes cancer-associated retinopathy (CAR) and melanoma-associated retinopathy (MAR). Emerging evidences indicate that PR is mediated by immune cross-reaction between circulating antibodies originally generated against remote tumor with antigens expressed on retinal neurons. It is believed that CAR is a consequence of the autoantibodies against the photoreceptors and MAR is the autoantibodies against the retinal ON-bipolar cells. Recoverin autoantibody in serum is closely related to the pathogenesis of CAR, and the inactivation of TRPM1 channel plays a key role in dysfunction of ON-bipolar cells in MAR. PR is characterized by visual dysfunctions, including decreased vision, night blindness, shimmering or flickering, and abnormalities of symbolic electroretinogram appearances. Based on the history of tumors, ophthalmic symptoms, and existence of circulating antibodies, it is easy to make a diagnosis of PR. Immunosuppressants and glucocorticoids may improve the visual dysfunctions in PR subjects.