Autoimmune Retinopathy – Causes, Symptoms, Diagnosis, Treatment

Autoimmune? retinopathy represents a spectrum of retinal degenerative disorders and rare autoimmune diseases that primarily affect retinal photoreceptor function with that including paraneoplastic (PAIR) and nonparaneoplastic (nPAIR) sub­types caused by cross-reactivity of serum autoantibodies against retinal antigens and leads to progressive vision loss. In Autoimmune Retinopathy (AIR) the body’s own defence mechanism starts attacking tissues by mistake, in this case the retina?, as opposed to in a genetic? condition like inherited? sight loss which leads to retinal degeneration. Included in this spectrum are cancer-associated retinopathy (CAR), melanoma?-associated retinopathy (MAR), and presumed non-paraneoplastic autoimmune retinopathy (npAIR). Autoimmune retinopathy typically presents in the fifth and sixth decades with rapidly progressive, bilateral?, painless visual deterioration?. Examination of the fundus? (the back inner part of the eye) is usually normal at presentation. The underlying reason for the autoimmune attack on retinal cells remains unknown. Treatment includes systemic? immunosuppression with steroid? and steroid-sparing agents, intravenous immunoglobulin (IVIG), and plasmapheresis (plasma exchange).

Autoimmune retinopathy represents a spectrum of rare autoimmune diseases that primarily affect retinal photoreceptor function and lead to progressive vision loss. Included in this spectrum are cancer-associated retinopathy (CAR), melanoma-associated retinopathy (MAR) and presumed non-paraneoplastic autoimmune retinopathy (npAIR). Autoimmune retinopathy typically presents in the fifth and sixth decades with rapidly progressive, bilateral, painless visual deterioration. Examination of the fundus (the back inner part of the eye) is usually normal at presentation. ^[1][2] The underlying reason for the autoimmune attack on retinal cells remains unknown. Treatment includes systemic immunosuppression with steroid and steroid-sparing agents, intravenous immunoglobulin (IVIG), and plasmapheresis (plasma exchange).^[1]

Types

Definition

The disease may be subdivided into paraneoplastic and non-paraneoplastic AIR. When related to melanoma, it is referred to as MAR, and when related to other cancers, it is called CAR.

Cancer-associated retinopathy

A division of AIR, cancer-associated retinopathy is a paraneoplastic syndrome , which is a disorder caused by an immune system response to an abnormality?. Autoimmune antibodies  attack target proteins in retinal photoreceptor cells. The proteins targeted as antigenic are recovering, may α‐enolase, and transducin.^[rx] This autoimmune response leads to photoreceptor cell death in ratina.^[rx] It causes progressive vision loss that can lead to blindness.^[rx] CAR is typically associated with the anti-recoverin antibody.^[rx]

Melanoma-associated retinopathy

Retinal bipolar cells in the retina transmit signals to react with the antibodies, leading to cell death. Although it is less prevalent than CAR, diagnosed cases of MAR continue to increase while CAR numbers decrease.^[rx]

Symptoms

Both CAR and MAR share the about to same symptoms. This is because they are both paraneoplastic syndromes. AIR symptoms are numerous and shared by many other diseases.^[rx]

• Patients present with vision problem with bilateral and asymmetric scotomas, photopsia, visual field defects, with rapidly progressive visual loss in late-onset?.
• In the initial stage, fundus examination is unremarkable, and in late stages, there is limited retinal  vascular attenuation, with or without optic disc pallor, associated or not with intraocular inflammation? and with no evidence of degenerative retinal disease.
• Painless Vision Loss
• Blind Spots in Vision
• Photopsia
• Nyctalopia
• Scotomas
• Dislike/avoidance of light
• Loss of contrast sensitivity
• Decreased night vision
• Subacute? vision loss
• Eye floaters or flashes
• Blind spots
• Decreased color vision
• Bilateral, slowly progressive vision loss
• Prolonged glare after light exposure
• Decreased color perception
• Central blindspots
• Poor night vision

Diagnosis?

Ophthalmologic and complementary examinations such as full-field electroretinogram, optical coherence tomography, visual field and fundus autofluorescence, help the diagnosis.[rx]

Diagnosis of AIR can be difficult due to indentify of symptoms with other disorders.^[rx] Examination of the fundus of ratina (inner surface of eye) can show no results or it can show narrowing of the blood vessels, the abnormal color of the optic disc, and retinal atrophy? with spasm?.^[rx][rx] Fundus examination results are not indicate of autoimmune retinopathy but they are used to initiate the diagnostic process. An electroretinogram (eye test used to see abnormalities in the retina) is used to detect AIR. An abnormal electroretinogram (ERG) with respect to light and dark adaptations indicates AIR.^[rx] The ERG also allows differentiation between cancer-associated retinopathy and melanoma-associated retinopathy.^[rx] If the ERG shows cone responses, CAR can be prematurely diagnosed.^[rx] If the ERG shows a significant decrease in b-wave amplitude, MAR can be prematurely diagnosed.^[rx][rx] To confirm, analysis for anti-retinal antibodies through Western blotting of serum collected from the patient is done.^[rx][rx]

Treatment

Due to the difficulty of diagnosis, managing this disease is a challenge. For this reason, there is no established treatment for AIR. Clinicians try to reduce and control the autoimmune system attack to prevent any irreversible retinal damage.^[rx] Methods of treatment include intravenous immunoglobulin (IVIG), plasmapheresis, and corticosteroids.^[rx]

Immunoglobulin

Immunoglobulin samples are get from a large pool of healthy, matched donors (10000 – 20000).^[rx] The immunoglobulin mixture is then administered through IV at a rate of 0.4g/kg/day for 5 days.^[rx] Antibodies in the IVIG mixture interact with binding in the site of the disease-associated antibodies (such as anti-recoverin antibodies).^[rx] This prevents binding to proteins targeted to disease and reduces disease activity.^[rx] Responses to this treatment can vary and are effects if the patient is diagnosed with any type of cancer.^[rx] Patients who respond positively improve in the clarity of their vision and their visual field.^[rx]

Plasmapheresis

Plasmapheresis involves separating blood into two parts of blood cells and plasma.^[11] The blood plasma components, such as the antibodies, are treated outside of the body. After removal of the disease-associated antibodies, the blood cells and plasma are transferred back into the body.^[rx] Response to this treatment depends on how much and quantity retinal damage has been done. Patients who respond positively show significant visual gains.^[rx]

Corticosteroids

Corticosteroids are administered through intravenous IV or orally. They cause lymphocytopenia, a condition where white blood cell levels are abnormally low.^[rx] Corticosteroids cause white blood cell death, lowering their amount throughout the body.^[rx] They also caused the white blood cells to recirculate away from the area of damage (the retina).^[rx] This minimizes damage caused by the antibodies produced by the white blood cells. Often, this is treatment is combined with the plasmapheresis process.^[rx] Instead of treating the plasma and blood cells, they are healthy donor mixture. Patients who respond positively show improved visual fields and almost complete disappearance of anti-retinal antibodies.^[rx]

References