How to differentiate autoimmune retinopathy and inherited RP

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Recently we have received some patients’ inquiries, they are concerned they have been misdiagnosed and that unlike in the case of inherited sight loss, they want to know more about autoimmune retinopathy, AIR for short.

What is AIR?

Autoimmune retinopathy (AIR) is a term given for patients who have a rare autoimmune condition that results in loss of photoreceptor (rods and cones) function. The immune system protects us against infection, cancer and damaged cells. The orchestrators of the immune system are our white blood cells that are rapid in their response to insults and part of their role is to remove the ‘danger’. To do this the white blood cells called B cells produce antibodies that attack the infection or damaged cells. However, sometimes the immune system is unable to differentiate between its own proteins from an infection. When this happens, conditions called autoimmune diseases may prevail, and AIR is thought to be an example of such an autoimmune disease.

How to differentiate AIR with inherited RP?

Often AIR is characterised by initial visual field defects and episodic flashing lights (photopsia) and night blindness (nyctalopia) resulting potentially in significant vision loss. To the doctor the appearance of the eye can look normal for some time and in particular the retina (fundoscopy) is healthy looking, initially. Later in the disease, there can be pigmentary changes at the macular of the retina and very late in the disease, the retinal vessels are thinned and theoptic disc has a waxy pale appearance.

How to confirm diagnose of AIR?

Autoretinal antibodies are detected by specialised laboratories using techniques known as ELISA and Western blot and immunohistochemistry.

Other ancillary tests may help the clinician make a diagnosis including testing the electrical function of the retina and enhanced imaging of the retina.

How is AIR treated?

There is no clear guidance on the best treatment options. In general, most specialists choose to treat with drugs or agent that suppress the immune system (called immunomodulation) but at best remains empiric in choice of drug. Such drugs include (and not exclusively): Steroids, mycophenolate mofetil, targeted B cells therapy (Rituximab) and intravenous immunoglobulin therapy (IVIG).