Thyroid eye disease
Pathogenesis: organ-specific autoimmune reaction in which a humoral agent (IgG antibody) produces inflammation and swelling of orbital tissue, especially extraocular muscles. It consists of an active inflammatory stage (<3 years) followed by a quiescent/fibrotic stage.
Diagnosis
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Lid retraction: (a) superior lid margin is either level with or above the superior limbus, with ‘scleral show’ ( Fig. 3.1 ), (b) Von Graefe sign (‘lid lag’) describes retarded descent of the upper lid on downgaze, and (c) inferior lid retraction.
Fig 3.1
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Ocular surface involvement: (a) grittiness, photophobia, lacrimation, and retrobulbar discomfort, (b) conjunctival hyperaemia, (c) chemosis and lid swelling ( Fig. 3.2 ), and (d) superior limbic keratoconjunctivitis (SLK; see Chapter 5 ).
Fig 3.2
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Axial proptosis: if severe, along with lid retraction ( Fig. 3.3 ) may compromise lid closure resulting in exposure keratopathy.
Fig 3.3
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Restrictive myopathy: motility defects in order of frequency are (a) elevation ( Fig. 3.4 ), abduction, depression, and adduction; (b) intraocular pressure increase in upgaze (Braley sign).
Fig 3.4
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Optic neuropathy: compression of the optic nerve by enlarged muscles ( Fig. 3.5 ); optic disc often appears normal.
Fig 3.5
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Treatment
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Lid retraction: (a) lid taping during sleep, (b) surgery (disinsertion of Müller muscle, levator recession, recession of the lower lid retractors) for stable retraction, but only after first addressing proptosis and strabismus, and (c) botulinum toxin chemodenervation for temporary effect.
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Ocular surface involvement: (a) lubricants, (b) topical anti-inflammatory agents (e.g. steroids, nonsteroidal anti-inflammatory drug [NSAIDs], ciclosporin), and (c) specific treatment of SLK.
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Proptosis: (a) systemic steroids (e.g. oral prednisolone, initially 60–80 mg with tapering on response) in acute sight-threatening cases, (b) radiotherapy (takes weeks–months for effect) in addition to steroids or when these are contraindicated, and (c) orbital decompression ( Fig. 3.6 ) is sometimes used acutely, but more commonly is reserved for the quiescent phase.
Fig 3.6
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Restrictive myopathy: (a) initially prisms, (b) surgery (inferior and/or medial rectus recessions with adjustable sutures) for diplopia in the primary or reading positions of gaze once stable for at least 6 months, and (c) botulinum toxin injection.
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Optic neuropathy: (a) systemic steroids (oral prednisolone or intravenous methylprednisolone), and (b) surgical decompression if steroids are ineffective or inappropriate; vision, particularly colour, should be monitored carefully.
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Infections
Preseptal cellulitis
Pathogenesis: infection of subcutaneous tissue anterior to the orbital septum. Causes include (a) skin trauma ( S. aureus , S. pyogenes ), and (b) spread from local or remote infection (e.g. stye, dacryocystitis, sinusitis).
Diagnosis
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Presentation: unilateral tender, red and swollen lid ( Fig. 3.7 ).
Fig 3.7
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Signs: proptosis and chemosis are absent, and optic nerve function and ocular motility are unimpaired.
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CT: opacification anterior to the orbital septum ( Fig. 3.8 ).
Fig 3.8
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Treatment: oral antibiotics (e.g. co-amoxiclav) are usually adequate; severe infection/abscess may require intravenous administration.
Bacterial orbital cellulitis
Pathogenesis: life-threatening infection of the tissues behind the orbital septum, more common in children. Causes include; (a) secondary to sinusitis (most common), (b) spread from local or remote infection, (c) post-trauma, and (d) post-surgery; common isolates are S. pneumoniae , S. aureus , S. pyogenes , and H. influenzae .
Diagnosis
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Presentation: rapid onset of pain, visual impairment, malaise, and periocular swelling.
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Signs: (a) unilateral tender warm and red periorbital oedema, (b) proptosis, (c) painful ophthalmoplegia ( Fig. 3.9 ), and (d) optic nerve dysfunction.
Fig 3.9
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Ocular complications: (a) exposure keratopathy, (b) optic atrophy, (c) retinal vascular occlusion, and (d) endophthalmitis.
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Other serious complications: (a) subperiosteal abscess, (b) meningitis, and (c) cavernous sinus thrombosis (bilateral rapidly progressive proptosis with abrupt general deterioration).
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Investigations: (a) CT of orbit ( Fig. 3.1 0 ), sinuses, and brain, (b) white cell count, (c) blood culture, (d) nasal swab for culture, and (e) lumbar puncture if meningeal signs develop.
Fig 3.10
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Treatment
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Hospital admission with otorhinolaryngological co-management.
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Urgent intravenous antibiotic therapy (e.g. cephalosporin or vancomycin, with metronidazole to cover anaerobes).
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Frequent ophthalmic review including optic nerve function.
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Surgical drainage of (a) infected sinuses and orbital collections if lack of response to antibiotics, or (b) subperiosteal/intracranial abscess.
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Orbital biopsy may be considered if atypical.
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Non-infective inflammatory disease
Idiopathic orbital inflammatory disease (IOID)
Pathogenesis: non-neoplastic and non-infective cellular infiltration that may involve any of the soft tissues of the orbit; previously referred to as ‘orbital pseudotumour.’
Diagnosis
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Presentation: acute or subacute onset of periorbital redness, swelling ( Fig. 3.11 ), and pain.
Fig 3.11
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Signs: (a) proptosis, (b) conjunctival hyperaemia and chemosis, (c) ophthalmoplegia, and (d) optic nerve dysfunction if the posterior orbit is involved.
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CT: ill-defined opacification ( Fig. 3.1 2 ).
Fig 3.12
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Course: varies from spontaneous remission without sequelae to severe prolonged inflammation with fibrosis (‘frozen orbit’).
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Differential diagnosis: (a) bacterial orbital cellulitis, (b) acute thyroid eye disease, and (c) systemic inflammatory disorder (e.g. Wegener granulomatosis).
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Treatment: observation for very mild disease; options in moderate-severe cases include NSAIDs, systemic steroids, radiotherapy, and antimetabolites.
Acute dacryoadenitis
Pathogenesis: usually idiopathic but occasionally infective (mumps, mononucleosis, rarely bacterial).
Diagnosis
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Presentation: acute discomfort with swelling of the lateral eyelid.
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Signs: (a) S-shaped ptosis and slight downward and inward dystopia ( Fig. 3.13 ), and (b) local tenderness, with conjunctival injection overlying the lacrimal gland ( Fig. 3.14 ).
Fig 3.13
Fig 3.14
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Imaging: enlargement of the lacrimal gland.
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Differential diagnosis: ruptured dermoid cyst and malignant lacrimal gland tumour.
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Treatment: spontaneous resolution is the rule; otherwise as for IOID.
Tolosa–Hunt syndrome
Definition: idiopathic condition characterized by granulomatous inflammation of the cavernous sinus, superior orbital fissure, and/or orbital apex.
Diagnosis
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Presentation: diplopia associated with unilateral periorbital or hemicranial pain.
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Signs: (a) proptosis is mild or absent, (b) ophthalmoplegia, often with pupillary involvement, and (c) sensory loss (first and second trigeminal divisions).
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Course: remissions and recurrences are common.
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Treatment: systemic steroids.
Vascular abnormalities
Varices
Definition: weakened orbital venous segments, usually unilateral and involving the upper nasal orbit.
Diagnosis
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Presentation: from early childhood to late middle age.
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Signs: (a) intermittent nonpulsatile proptosis not associated with a bruit, precipitated by coughing, straining, or assuming a dependent position ( Fig. 3.15 ), (b) often demonstrable with the Valsalva manoeuvre or jugular vein compression, and (c) coexisting varices of the eyelids ( Fig. 3.16 ) and conjunctiva ( Fig. 3.17 ) may be present.
Fig 3.15
Fig 3.16
Fig 3.17
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Imaging: may show phleboliths.
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Complications: acute haemorrhage and thrombosis, and orbital fat atrophy.
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Treatment: indications include recurrent thrombosis, pain, severe proptosis and optic nerve compression; surgical excision is difficult as the lesions are friable.
Carotid–cavernous fistula
Introduction
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Definition: acquired communication between the carotid artery and the cavernous sinus resulting in increased episcleral venous pressure and decreased arterial blood flow. There are two types:
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Direct fistula: high-flow shunt with intracavernous carotid arterial blood passing directly into the sinus; trauma is responsible for 75%, spontaneous rupture of an aneurysm or atherosclerotic artery accounting for the remainder.
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Indirect fistula: low-flow shunt in which arterial blood flows indirectly into the cavernous sinus through the meningeal branches of the external or internal carotid arteries; frequently spontaneous or following straining.
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Diagnosis of direct fistula
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Presentation: days or weeks after head injury with the classic triad of (a) pulsatile proptosis, (b) chemosis, and (c) whooshing noise in the head.
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Signs: (a) conjunctival injection and haemorrhagic chemosis ( Fig. 3.18 ), (b) ophthalmoplegia and ptosis (3rd nerve involvement), (c) pulsatile proptosis associated with a thrill and a bruit; may be abolished by ipsilateral carotid compression ( Fig. 3.19 ), (d) increased intraocular pressure, (e) anterior segment ischaemia (corneal epithelial oedema, aqueous cells and flare), (f) optic disc swelling, and (g) retinal venous dilatation.
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