Ptosis
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Introduction

Ptosis may be unilateral or bilateral – symmetrical or asymmetrical
Upper lid lifted by contraction of levator (CN III) and sympathetic innervation of smooth muscle component
Lids closed by orbicularis oculi (CN VII) – facial nerve palsy does not cause ptosis
Enonphthalmos (e.g. orbital wall fracture) and proptosis may give the appearance of ptosis in unaffected eye.
Dermatochalasis: excess skin of upper lid, may sag below lid margin.
Causes of ptosis: involutional changes, CN III palsy, myasthenia gravis, levator trauma, Horner’s syndrpme and mitochondrial myopathies.

  • Involutional changes: loss of connection between levator and eyelid skin – usually bilateral.
  • CN III palsy: divergent squint and, in some cases, dilated pupil.
  • Myasthenia gravis: antibodies to nicotinic acetylcholine receptors.
    • Initial presentation may be ocular – ptosis variable and fatigable, abnormal eye movements leading to diplopia.
  • Trauma: sever connections between levator and skin.
  • Horner’s syndrome: sympathetic innervation of Muller’s muscle (smooth muscle of levator) disrupted, ptosis accompanied by small pupil and dryness of skin on affected side.
  • Mitochondrial myopathies: rare, inherited from mother. Retinal pigmentation and cardiac conduction abnormalities.

Examination

  • Confirm presence of a ptosis and determine if congenital or acquired.
  • Compensation through action of frontalis (firmly press against the brow).

Management

  • Surgical restoration of levator-skin connection
  • Myasthenia gravis is managed with anticholinesterase inhibitors
  • Simple lid-lifting devices
  • In CN III palsy, elevating lid may lead to disabling diplopia

References

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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) currently works as a GP Registrar and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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