Forward displacement of the eye from any process that increases the orbital content.

Exophthalmos and proptosis are generally used interchangeably.

Exophthalmos is generally considered an endocrine related ocular protrusion while proptosis is a non-endocrine related condition.

Can lead to incomplete covering of the eye by the eyelids and the tear film may not be distributed evenly over the cornea, leading to pain and possible corneal infection.

Can be forward (axial) or positional.

The differential diagnosis includes: Graves’ disease, Wegener’s granulomatosis, sarcoidosis, orbital myositis, idiopathic inflammation, infection, and malignancy.

In adults thyroid ophthalmopathy, an autoimmune inflammatory orbital disease, is the most common cause of exophthalmos in adults.

In most cases of thyroid ophthalmopathy no therapy is required, however steroids, radiation, and surgical decompression may you be used in severely refractory situations.

Graves disease causes axial proptosis by the accumulation of extracellular matrix proteins and variable fibrotic changes in the rectus muscles.

Any enlargement of the lacrimal glands can cause proptosis as it displaces the eye inferiorly and medially as the lacrimal gland is superior and lateral in the orbit.

Masses in the corner of the orbit formed by the horizontal rectus muscles causes the eye to bulge forward, axial proptosis.

The floor of the orbit is the maxillary sinus and the medial wall of the orbit separates the orbit from the ethmoid sinuses.

Sinus infection can spread to the orbits.

The orbital septum is divided into anterior and posterior compartments.

Orbital cellulitis is a deep soft tissue infection posterior to the orbital septum and preseptal cellulitis is a superficial soft tissue infection anterior to that septum.

Orbital cellulitis is most commonly due to extension of bacterial sinusitis and usually presents with blurred vision, fever, diplopia, and exophthalmos.

Mucormycosis is a potentially life-threatening fungal infection that may be present in immunocompromised hosts and may present with orbital cellulitis.

Wegener’s may involve the orbit primarily or spread the orbit by its sinus involvement.

Optic nerve gliomas or meningioma cause axial proptosis.

Treatment depends on the underlying condition and may include anti-neoplastic therapy, anti-infectious agents, and systemic immunosuppression.

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