Idiopathic orbital inflammatory syndrome (IOIS)

Definition

The orbit is a bony, pyramid-shaped cavity in the skull. It contains and protects the eyeball and related structures. Orbital pseudotumor is a swelling of the orbital tissues behind the eye, but unlike cancerous tumors, it cannot invade other tissues or spread elsewhere.

Alternative Names

Causes

The cause is unknown. It most commonly affects young women, although it can still occur at any age.

Symptoms

• Pain on eye movement
• Decreased vision
• Eyelid swelling
• Red eye (rare)

Exams and Tests

The changes of pseudotumor can be seen when the eye is examined. Tests to differentiate a pseudotumor from a tumor include the following:

• Ultrasound
• Skull x-ray
• Biopsy

Treatment

Mild cases may go away without treatment. More severe cases will usually respond to treatment with corticosteroids. Very severe cases may develop damaging pressure on the eye, and require surgical movement of the bones of the orbit, to relieve pressure on the eyeball.

Outlook (Prognosis)

Most cases are mild and do well. Severe cases may be resistant to treatment and visual loss may occur. Orbital pseudotumor usually involves only one eye.

Possible Complications

Severe cases of orbital pseudotumor may push the eye forward to the extent that the lids can no longer protect the cornea, leading to drying of the affected eye. This can lead to damage to the clarity of the cornea, or to corneal ulcer (wound). The eye muscles may not be able to properly aim the eye, and double vision may result.

When to Contact a Medical Professional

Patients with pseudotumor will be closely followed by an ophthalmologist with experience in the treatment of orbital disease.

If you experience irritation of the cornea, redness, pain, or decreased vision, call your ophthalmologist or general health care provider right away.