Autoimmune 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 target proteins in retinal photoreceptor cells. The proteins targeted as antigenic are recoverin, α‐enolase and transducin.[4] This autoimmune response leads to photoreceptor cell death.[4] It causes progressive vision loss that can lead to blindness.[5] CAR is typically associated with the anti-recoverin antibody.[2]

Retinal bipolar cells (cells in retina that transmit signals) 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.[2]

Immunoglobulin samples are obtained from a large pool of healthy, matched donors (10000 - 20000).[9] The immunoglobulin mixture is then administered through IV at a rate of 0.4g/kg/day for 5 days.[5] Antibodies in the IVIG mixture interact with binding sites of the disease-associated antibodies (such as anti-recoverin antibodies).[9] This prevents binding to proteins targeted as antigenic and reduces disease activity.[9] Responses to this treatment can vary and are impacted if the patient is diagnosed with any type of cancer.[10] Patients who respond positively show improvement in the clarity of their vision and their visual field.[9]

Plasmapheresis involves separating blood into two parts - 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 transfused back into the body.[11] Response to this treatment depends on how much retinal damage has been done. Patients who respond positively show significant visual gains.[5]

Corticosteroids are administered through IV or orally. They cause lymphocytopenia, a condition where white blood cell levels are abnormally low.[12] Corticosteroids cause white blood cell death, lowering their numbers throughout the body.[12] They also cause white blood cells to recirculate away from the area of damage (the retina).[12] This minimizes damage caused by the antibodies produced by the white blood cells. Often, this is treatment is combined with plasmapheresis.[5] Instead of treating the plasma and blood cells, they are replaced with a healthy donor mixture. Patients who respond positively show improved visual fields and an almost complete disappearance of anti-retinal antibodies.[13]