Introduction
Autoimmune retinopathy is a collective term used for a group of immune-mediated inflammatory retinal disorders of degenerative type. It is assumed that they are caused by the abnormal cross-reaction between the serum autoantibodies and the retinal antigens. Autoimmune retinopathy has a wide spectrum and consists of various clinical entities with overlapping clinical presentations. The most common clinical manifestation is bilateral, gradually degenerative, rapidly progressive, painless vision deterioration. Autoimmune retinopathy was first reported in the year 1976 by Sawyer et al.
What Are the Types of Autoimmune Retinopathy?
Autoimmune retinopathy can be subdivided into paraneoplastic autoimmune retinopathy and non-paraneoplastic autoimmune retinopathy.
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Paraneoplastic Autoimmune Retinopathy: Cancer-associated retinopathy and melanoma-associated retinopathy are included in this category.
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Non-paraneoplastic Autoimmune Retinopathy: It is a type of clinical entity that occurs in the absence of malignancy. It is used as a diagnosis of exclusion.
What Is the Epidemiology of Autoimmune Retinopathy?
Autoimmune retinopathy is a very rare disorder. Of all the clinical phenotypes, non-paraneoplastic autoimmune retinopathy is the most prevalent autoimmune retinopathy and cancer-associated retinopathy is the most commonly found paraneoplastic autoimmune retinopathy. Females are more commonly affected than males. The onset of the disorder most commonly occurs in the age group of 50 to 60 years. Other cancers have also been found to be associated with cancer-associated retinopathy such as small-cell carcinoma of the lung, breast cancer, cancer of the uterus, ovarian cancer, and cervical cancer.
What Is the Pathogenesis of Autoimmune Retinopathy?
The pathogenesis of the disorder involves the circulation of antiretinal antibodies that are directed against the retinal antigens and attack them. These retinal antigens are retinal proteins with immunologic properties. Recoverin and enolase have been identified as the two main retinal proteins. The antibody that is targeted towards recoverin causes degeneration of the retinal rods and cones by the process of apoptosis. Enolase enzyme is found in the cell membranes of ganglion cells, rods, and cones in the retina. Viral or bacterial infection can act as a triggering agent for this autoimmune reaction.
What Are the Clinical Features of Autoimmune Retinopathy?
The clinical features of cancer-associated retinopathy and melanoma-associated retinopathy are almost similar because both of them are paraneoplastic disorders.
The main symptoms include:
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Vision loss is painless and can be permanent.
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Blind spot (the area where the optic disk is passed by the optic nerve) formation in vision.
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Photopsia (presence of light flashes in the field of vision).
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Nyctalopia (a condition characterized by the inability of the individual to see at night due to vitamin A deficiency).
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Scotomas (partially diminished visual area in the retina).
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Avoidance of light (photopsia).
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Lack of contrast sensitivity.
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Partial color blindness.
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Reduced night vision.
How Is Autoimmune Retinopathy Diagnosed?
The patient needs to be investigated thoroughly. The diagnosis is quite difficult due to overlapping clinical features with other similar diseases. Ophthalmic examination of the inner surface of the eye (fundus of the eye) is usually carried out. Fundus examination exhibits blood vessel constriction, discoloration of the optic disc, and retinal degeneration. However, the results of the fundus examination are not sufficient to establish the diagnosis of the lesion. An electroretinogram (eye test that is used to see the retinal abnormalities) is usually performed to detect autoimmune retinopathy. An abnormal electroretinogram in response to light and dark adaptations is suggestive of autoimmune retinopathy. The electroretinogram also helps to distinguish between the various types of paraneoplastic retinopathies. If cone responses are seen in the electroretinogram, cancer-associated retinopathy may be diagnosed at an earlier stage. Melanoma-associated retinopathy can be diagnosed if the electroretinogram shows a considerable reduction in b-wave amplitude. Western blotting of the patient’s serum can be carried out to analyze the retinal antibodies to confirm the diagnosis of autoimmune retinopathy.
What Is the Treatment of Autoimmune Retinopathy?
A multidisciplinary team is crucial for the appropriate treatment and control of the disorder. The possibility of neoplasia can be investigated by an oncologist in cases of cancer-associated neoplasia. A rheumatologist, ophthalmologist, and other specialists are required to work in a well-coordinated manner to treat this rare condition. Immunosuppressive drugs such as Azathioprine, Cyclosporine, Infliximab, and intravenous immunoglobulins are usually suggested by the healthcare professional for the therapy. It usually takes years to treat the condition.
Corticosteroids are also recommended by the doctor to stabilize the disease. Combined therapy is usually preferred to treat the condition. Plasmapheresis (the process of plasma removal from the blood of the patient after withdrawing it) is also considered a treatment modality but this treatment approach is more effective when applied before the visual loss. This technique works by reducing the number of circulating antibodies thereby reducing the damage to the photoreceptors.
Visual field examination along with electroretinography should be repeated every three to six months for follow-up and to monitor the condition of the patient. In cases of malignant tumors, management can be done with the help of surgery, chemotherapy, and radiotherapy. However, these procedures do not alter the prognosis of visual signs and symptoms. In addition to immunosuppression therapy, multivitamin supplements with antioxidants such as beta-carotene, lutein, ascorbic acid, and vitamin E can be suggested to reduce retinal degeneration.
What Is the Prognosis of Autoimmune Retinopathy?
It is difficult to diagnose the condition. So, it is a challenging task to manage the disease. No specific treatment has been established for autoimmune retinopathy till date. So, it is important to seek medical advice at an early stage to prevent irreveresible damage to the retina.
Conclusion
Autoimmune retinopathy is an uncommon disease entity in which the immune system of the patient attacks the proteins present in the retina. This can often lead to loss of vision in the affected individual. Since it is very difficult to diagnose the disease because of its clinical similarities to other disorders, it is very important to maintain a high level of a suspicion index to always remain alert while diagnosing the disorder. Early diagnosis and therapeutic management may play a crucial role to decrease the immunological risk of irreversible damage to the patient’s retinal cells in autoimmune retinopathy. A multi-disciplinary team should be approached for thorough evaluation and treatment of the condition.
