• Clinical science

Orbital disorders

Abstract

The orbital cavity (eye socket) is the bony cavity that encloses the bulb and accessory organs of the eye such as the ocular muscles, lacrimal glands, nerves, vessels, and retrobulbar adipose tissue. Diseases of the orbital cavity include Graves ophthalmopathy, orbital cellulitis, rhabdomyosarcoma, and lacrimal sac disorders. Typical symptoms associated with these diseases include exophthalmos and diplopia. Treatment differs according to the underlying disease and includes conservative measures (antibiotics), surgery, radiotherapy, and chemotherapy.

Disorders of the lacrimal system are discussed in a separate learning card.

Graves ophthalmopathy

  • Definition: Graves ophthalmopathy or orbitopathy (GO) (also known as thyroid-associated orbitopathy or ophthalmopathy, TAO) is an autoimmune condition that is generally associated with Graves disease
  • Etiology
  • Epidemiology
    • Sex: > Although it is more common in women, severe cases occur more frequently in men and patients > 50 years of age.
    • Risk factors: family history of Graves disease and tobacco smoking
  • Pathophysiology
    • TSH autoantibodies are present in the orbital cavity; (eye socket) → bind TSH receptor antigen; (autoimmune reaction) on cells → lymphocytic infiltration into the orbital tissuesinflammation and release of cytokines from CD4+ T cells; stimulates fibroblasts to secrete glycosaminoglycans (hyaluronic acid), which also pulls water into the interstitial space (osmotic effect); expansion of retro-orbital tissue due to increased fluid in extraocular muscles, lymphocytic infiltration, and adipogenesis
  • Clinical features
    • Exophthalmos : can be unilateral or bilateral, often asymmetric. Retropulsion (palpation of the globe while the eyelid is closed) enable adequate examination.
    • Ocular motility disturbances
    • Lid retraction, also known as thyroid stare”
    • Joffroy sign: absent forehead creases during superior gaze
    • Conjunctival injection and chemosis
    • Ocular discomfort (pain or pressure)
    • Photopsia on upward gaze
    • Patient may be hyperthyroid, euthyroid, or hypothyroid.
    • Loss of vision is uncommon.
    • There are several severity scales, but treatment is based on mild active disease vs. severe active disease, and whether or not the patient has a risk of blindness.
    • Severity is associated with level of TSAb, but not associated thyroid function.
  • Diagnosis
  • Differential diagnosis: pseudoexophthalmos
    • Short description: Exophthalmos is suspected as a result of the enlarged eyes.
    • Frequent causes
      • Severe myopia
      • Hydrophthalmia
      • Contralateral enophthalmos
  • Treatment
    • Principles
      • This is a self-limiting disease, but intervention may be necessary because of severe symptoms or risk of complications.
      • Goals of therapy include treatment of hyperthyroidism, smoking cessation, eye protection, and decreasing inflammation.
      • Radioiodine therapy may initially worsen the appearance and symptoms of the disease, while surgery and thioamides do not affect the disease.
      • If radioiodine therapy is used, steroids are recommended before and after treatment.
    • Mild disease
    • Moderate to severe inflammation, nonresponders, or threatened/manifested vision loss: high-dose IV steroids
      • If response is good: consider orbital radiation
      • If no response after 48–72 hours → surgical decompression while on steroids in the following order:
        • Orbital decompression
        • Strabismus correction
        • Lid-lengthening surgery
        • Blepharoplasty
      • Other options for patients who are refractory to treatment or poorly tolerate glucocorticoids: rituximab, cyclosporine, octreotide, intravenous immunoglobulin, and tarsorrhaphy

References:[1][2][3][4]

Orbital cellulitis

Reduced vision, diplopia, ophthalmoplegia, and proptosis are typical features of orbital cellulitis, and do not occur in preseptal cellulitis!

References:[5][6]

Rhabdomyosarcoma

  • Definition: malignant mesenchymal tumor of primitive muscle cells
  • Epidemiology
    • Most common soft tissue sarcoma and malignant orbital tumor in children
    • Primarily occurs in the first decade of life.
  • Clinical features
    • Frequently in the orbital cavity, but can also be in the head and neck, urogenital region , or extremities
    • Growing orbital mass that may be painful and have potential hemorrhage
    • Proptosis or dysconjugate gaze
  • Diagnosis
    • Open or core needle biopsy for light microscopy to look for rhabdomyoblasts
    • X-ray of the primary site and chest: to determine any bone and lung involvement for staging
    • CT of the primary site and chest: to search for any lung metastases and bone destruction and determine therapeutic response
    • MRI: better to determine specific location of mass and any soft tissue invasion
  • Treatment
    • Surgery (complete excision) if a functional and cosmetic result is possible
    • Combination of radiation and chemotherapy following a diagnostic biopsy if complete excision is not feasible
  • Prognosis: more favorable for localized tumors of the orbit (> 80% 5-year survival), and less favorable for metastatic disease (< 30% 5-year event-free survival)

References:[7][8][9][10][11]