Clinical Anatomy of the Orbit
All orbital structures can be involved in orbital lesions (▶ Fig. 14.1). Because the orbit is an enclosed space surrounded by bones, any orbital process will result in proptosis (exophthalmos).
Fig. 14.1 Anatomy of the orbit (sagittal view through the eye and the optic canal). (From Schuenke M, Schulte E, Schumacher U, Ross LM, Lamperti ED, Voll M. THIEME Atlas of Anatomy, Head and Neuroanatomy. Stuttgart, Germany: Thieme; 2007. Illustration by Karl Wesker.)
14.2 Causes of Acute or Subacute Orbital Syndrome
Acute orbital syndromes are most often vascular or inflammatory, whereas subacute presentations are most likely secondary to tumors.
Vascular abnormalities
Carotid–cavernous sinus fistula
Cavernous sinus thrombosis
Superior ophthalmic vein thrombosis
Orbital varix
Orbital arteriovenous malformation
Inflammatory processes
Infectious
Bacterial orbital cellulitis
Fungal infections
Orbital tuberculosis
Noninfectious
Thyroid-related orbitopathy
Idiopathic orbital inflammation (inflammatory orbital pseudotumor)
Immunoglobulin G4 (IgG4) related disease
Sarcoidosis
Wegener granulomatosis
Giant cell arteritis
Polyarteritis nodosa
Tumors (only the most classic tumors in each age group are listed, in order of decreasing frequency)
Primary
Adults
Cavernous hemangioma
Lymphangioma
Schwannoma
Lymphoma
Optic nerve sheath meningioma
Children
Rhabdomyosarcoma
Lymphangioma
Capillary hemangioma
Optic nerve glioma
Cysts, including mucocele
Secondary/invasive
Sinonasal tumors
Brain tumors
Perineural spread of cutaneous tumors
Metastatic
Adults
Breast carcinoma
Bronchogenic carcinoma
Prostate carcinoma
Children
Neuroblastoma
Leukemia
Trauma
Orbital wall fractures
Retrobulbar hematoma
The clinical examination may help further differentiate among the possible etiologies, but imaging studies are imperative to ascertain the ultimate diagnosis. In the absence of diagnostic imaging findings, tissue biopsy is usually the next step in determining the cause of an orbital syndrome.
14.3 Features of Orbital Syndrome
The following symptoms and signs can reveal an orbitopathy:
Proptosis (exophthalmos)
Eyelid malposition
Retraction
Ptosis
Globe displacement
Ocular pulsations or orbital bruit
Vision loss
Optic neuropathy from
compression
infiltration
ischemia
Elevated intraocular pressure
Venous stasis causing
retinal hemorrhages
macular edema
serous retinal detachment
Diplopia
Extraocular muscle restriction
Venous engorgement
Mechanical limitation secondary to mass effect
Cranial neuropathy (secondary to nerve ischemia or direct compression)
Enophthalmos rarely (secondary to scarring with tissue retraction or bony orbital wall destruction)
14.3.1 Causes of Proptosis
Orbital space occupying lesions induce proptosis:
Thyroid eye disease
Orbital tumors
Orbital inflammatory pseudotumor
Orbital infection (cellulitis)
Orbital vascular malformations
Arteriovenous malformations
Orbital varix
Orbital venous congestion
Cavernous sinus fistula
Cavernous sinus thrombosis
Superior orbital vein thrombosis
Orbital hemorrhage
Bony deformations of the orbit
Fibrous dysplasia
Sphenoid wing hypoplasia
Trauma to the orbit
Pseudoproptosis
High myopia
Racial (common in blacks)
