Topical apraclonidine in the diagnosis of suspected Horner syndrome.

  title={Topical apraclonidine in the diagnosis of suspected Horner syndrome.},
  author={Kenn A. Freedman and Sandra Marie Brown},
  journal={Journal of neuro-ophthalmology : the official journal of the North American Neuro-Ophthalmology Society},
  volume={25 2},
Topical cocaine is used to confirm the clinical diagnosis of ocular sympathetic denervation, or Horner Syndrome (HS). Cocaine blocks re-uptake of norepinephrine (NE) by sympathetic nerve terminals in the iris dilator muscle, transiently increasing its concentration in the synaptic junction. Norepinephrine activates alpha1 receptors in the iris dilator to cause pupil dilation. In HS, cocaine fails to dilate the affected pupil as much as the unaffected pupil, but its indirect action makes it a… CONTINUE READING