Safety of apraclonidine eye drops in diagnosis of Horner syndrome in an outpatient pediatric ophthalmology clinic

J AAPOS. 2021 Dec;25(6):336.e1-336.e4. doi: 10.1016/j.jaapos.2021.07.011. Epub 2021 Nov 2.


Purpose: To describe the efficacy and systemic side effects of apraclonidine drops 0.5% in children clinically suspected of having Horner syndrome.

Methods: The medical records of patients with clinically suspected Horner syndrome who underwent testing with apraclonidine 0.5% eyedrops were reviewed retrospectively. The following data were retrieved from the record: allergic reactions, somnolence, shallow respiration, pallor, or excessive fussiness noted by the examiner or parents.

Results: A total of 46 patients presenting with anisocoria and tested with apraclonidine 0.5% were included. Of these, 15 had a positive result, with reversal of anisocoria. The mean age of patients was 3.2 years (median, 0.91; mode, 0.25 years). Twenty-four patients were ≤1 year of age; 19 were ≤6 months. No systemic side effects were noted during the examination or reported by parents in any patients.

Conclusions: The use of topical apraclonidine eyedrops has been described as an effective test for Horner syndrome. However, concerns have been raised regarding the potential systemic side effects in children, especially those under the age of 6 months. In our cohort, no systemic side effects were reported, including in those under 6 months of age.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Child
  • Child, Preschool
  • Clonidine / analogs & derivatives
  • Horner Syndrome* / chemically induced
  • Horner Syndrome* / diagnosis
  • Humans
  • Infant
  • Ophthalmic Solutions
  • Ophthalmology*
  • Outpatients
  • Retrospective Studies
  • Young Adult


  • Ophthalmic Solutions
  • apraclonidine
  • Clonidine