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. Only about 10% develop serious long-term ocular problems.
Diagnosis
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Lid retraction : (a) superior lid margin is either level with or above the superior limbus, with ‘scleral show’ ( Fig. 4.1A ), (b) von Graefe sign (‘lid lag’) describes retarded descent of the upper lid on downgaze, (c) inferior lid retraction.
Fig. 4.1
Thyroid eye disease: (A) lid retraction, (B) chemosis and lid swelling, (C) axial proptosis, (D) coronal CT scan showing symmetrical muscle enlargement.
(From Salmon JF, Kanski’s Clinical Ophthalmology: A Systematic Approach , 9th edition. Oxford, UK: Elsevier; 2020.)
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Ocular surface involvement : (a) grittiness, photophobia, lacrimation, and retrobulbar discomfort, (b) conjunctival hyperaemia, (c) chemosis and lid swelling ( Fig. 4.1B ), (d) superior limbic keratoconjunctivitis.
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Axial proptosis : if severe, along with lid retraction ( Fig. 4.1C ) may compromise lid closure resulting in exposure keratopathy.
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Restrictive myopathy : motility defects in order of frequency are: (a) elevation, abduction, depression and adduction, (b) intraocular pressure increase in upgaze.
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Optic neuropathy : compression of the optic nerve by enlarged muscles ( Fig. 4.1D ); optic disc often appears normal.
Treatment
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Lifestyle : patients should stop smoking.
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Ocular surface involvement : (a) lubricants, (b) topical anti-inflammatory agents (e.g. steroids, nonsteroidal anti-inflammatory drugs), (c) specific treatment of superior limbic keratoconjunctivitis (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, (c) orbital decompression is sometimes used acutely, but more commonly is reserved for the quiescent phase, (d) teprotumumab is a new monoclonal antibody which inhibits insulin-like growth factor 1 receptor and is effective in reducing clinical activity and proptosis.
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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, (c) botulinum toxin injection.
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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, (c) botulinum toxin chemodenervation for temporary effect.
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Optic neuropathy : (a) systemic steroids (oral prednisolone or intravenous methylprednisolone), (b) surgical decompression if steroids are ineffective or inappropriate; vision, particularly colour vision, should be monitored regularly.
Infections
Preseptal cellulitis
Pathogenesis:
infection of subcutaneous tissue anterior to the orbital septum. Causes include (a) skin trauma ( S. aureus , S. pyogenes ), (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. 4.2A ).
Fig. 4.2
Preseptal cellulitis: (A) secondary to infected skin abrasion, (B) axial CT showing opacification anterior to the orbital septum.
(From Salmon JF, Kanski’s Clinical Ophthalmology: A Systematic Approach , 9th edition. Oxford, UK: Elsevier; 2020.)
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Signs : proptosis and chemosis are absent. Optic nerve function and ocular motility are unimpaired.
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CT : opacification anterior to the orbital septum ( Fig. 4.2B ).
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: (a) secondary to sinusitis (most common), (b) spread from local or remote infection, (c) post-trauma, (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. 4.3A ), (d) optic nerve dysfunction.
Fig. 4.3
Orbital cellulitis: (A) proptosis with ophthalmoplegia, (B) axial CT showing preseptal and orbital opacification.
(From Salmon JF, Kanski’s Clinical Ophthalmology: A Systematic Approach , 9th edition. Oxford, UK: Elsevier; 2020.)
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Ocular complications : (a) exposure keratopathy, (b) optic atrophy, (c) retinal vascular occlusion, (d) endophthalmitis.
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Other serious complications : (a) subperiosteal abscess, (b) meningitis, (c) cavernous sinus thrombosis (bilateral rapidly progressive proptosis with abrupt general deterioration).
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Investigations : (a) CT of orbit ( Fig. 4.3B ), sinuses and brain, (b) white cell count, (c) blood culture, (d) nasal swab for culture, (e) lumbar puncture if meningeal signs develop.
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 metro-nidazole 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.
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 and pain ( Fig. 4.4A ).
Fig. 4.4
Idiopathic orbital inflammatory disease: (A) proptosis with ptosis, (B) axial CT showing ill-defined orbital opacification.
(From Salmon JF, Kanski’s Clinical Ophthalmology: A Systematic Approach , 9th edition. Oxford, UK: Elsevier; 2020.)
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Signs : (a) proptosis, (b) conjunctival hyperaemia and chemosis, (c) ophthalmoplegia, (d) optic nerve dysfunction if the posterior orbit is involved.
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CT : ill-defined opacification ( Fig. 4.4B ).
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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, (c) systemic inflammatory disorder (e.g. granulomatosis with polyangiitis).
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, infective 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. 4.5A ), (b) local tenderness, with conjunctival injection overlying the lacrimal gland.
Fig. 4.5
Acute dacryoadenitis: (A) swelling on the lateral aspect of the eyelid and S-shaped ptosis, (B) CT showing enlargement of the lacrimal gland and adjacent tissues.
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Imaging : enlargement of the lacrimal gland ( Fig. 4.5B ).
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Differential diagnosis : ruptured dermoid cyst and malignant lacrimal gland tumour.
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 hemi-cranial pain.
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Signs : (a) proptosis is mild or absent, (b) ophthalmoplegia, often with pupillary involvement, (c) sensory loss (first and second trigeminal divisions).
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Course : remissions and recurrences are common.
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 non-pulsatile proptosis not associated with a bruit, precipitated by coughing, straining, or assuming a dependent position, (b) often demonstrable with the Valsalva manoeuvre or jugular vein compression, (c) coexisting varices of the eyelids ( Fig. 4.6A ) and conjunctiva ( Fig. 4.6B ) may be present.
Fig. 4.6
Varices: (A) eyelid, (B) conjunctiva.
(From Salmon JF, Kanski’s Clinical Ophthalmology: A Systematic Approach , 9th edition. Oxford, UK: Elsevier; 2020.)
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Imaging : may show phleboliths.
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Complications : acute haemorrhage and thrombosis; orbital fat atrophy.
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, (c) ‘whooshing’ noise in the head.
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Signs : (a) conjunctival injection ( Fig. 4.7A ) and haemorrhagic chemosis ( Fig. 4.7B ), (b) ophthalmoplegia and ptosis (3rd nerve involvement), (c) pulsatile proptosis associated with a thrill and a bruit; may be abolished by ipsilateral carotid compression, (d) increased intraocular pressure, (e) anterior segment ischaemia (corneal epithelial oedema, aqueous cells and flare), (f) optic disc swelling, (g) retinal venous dilatation.
