Orbital Myositis is a very rare condition. It is a general term for inflammation of the muscles which control eye movement.
There are three typical symptoms:
• acute onset of pain in the eye which is exacerbated by movement
• double vision
• eyelid or conjunctival swelling or redness
Most cases involve only one eye but, repeated flares can occur and can migrate to a different muscle in the eye.
An ophthalmologist will be needed to identify which eye muscles are inflamed.
Initially an MRI may be helpful to identify the inflamed muscles.
A muscle biopsy may be required to exclude another diagnosis because eye inflammation can occur in other conditions. The biopsy is usually not very invasive and often undertaken under local anaesthetic. Your doctor will probably suggest stopping any steroid treatment for at least two weeks prior to a biopsy.
The cause is not easily identified. It can be an autoimmune response or connected with bacterial, viral or parasitic infection or a drug reaction or even a COVID-19 reaction. Other conditions also have to be considered such as a malignancy or autoimmune disease.
Treatment depends upon the severity and progression of the disease.
Mild cases with little pain, slow progression and few issues with eye-movement, may resolve with non-steroidal anti-inflammatory medications.
Moderate cases usually improve quickly with initial high dose corticosteroids e.g. prednisolone. The dosage is then tapered down over several months. Relapses can however occur when the dosage is tapered.
In recurrent or chronic cases, other immuno-suppressants such as methotrexate, infliximab or tocilizumab have been helpful.
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