What are the common ocular abnormalities of Horner syndrome?

Updated: May 01, 2019
  • Author: Christopher M Bardorf, MD, MS; Chief Editor: Edsel Ing, MD, MPH, FRCSC  more...
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Horner syndrome may develop from lesions at any point along the sympathetic pathway. [4] Abnormalities found in all patients, regardless of the level of interruption, include the following:

  • Mild-to-moderate ptosis, owing to denervation of the sympathetically controlled Müller muscle

  • Slight elevation of the lower lid (upside-down ptosis), owing to denervation of the lower lid muscle (analogous to the denervation of the Müller muscle in the upper lid)

  • Miosis and dilation lag, where pupillary dilation after psychosensory stimuli is slower in the affected pupil than in the unaffected pupil

Depending on the level of the lesion, impaired flushing and sweating may be found ipsilaterally. With central first-order neuron lesions, anhidrosis affects the ipsilateral side of the body. Lesions affecting second-order neurons may cause anhidrosis of the ipsilateral face. With postganglionic lesions occurring after vasomotor and sudomotor fibers have branched off the sympathetic chain, anhidrosis is either absent or limited to an area above the ipsilateral brow. The pupils react normally to light and accommodation.

Iris heterochromia (with the affected eye being hypopigmented) is seen in congenital Horner syndrome or Horner syndrome that occurs in children younger than 2 years. Iris heterochromia also may occur in long-standing Horner syndrome.

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