Tonic pupil after botulinum toxin-A injection for treatment of esotropia in children

J AAPOS. 2016 Feb;20(1):78-81. doi: 10.1016/j.jaapos.2015.09.011.


A total of 27 children with esotropia (mean age, 3.9 years; range, 9 months to 13.8 years) were enrolled in a 9-month observational study following botulinum toxin A (BTX-A) injection of one (n = 7) or both (n = 20) medial rectus muscles. BTX-A dosage ranged from 3.0 to 6.0 units per muscle. Three participants developed tonic pupil, noted at the first follow-up visit, occurring 12-19 days after injection. All 3 cases occurred in the left eye of participants who underwent bilateral BTX-A injection by the same surgeon. Anisocoria diminished from a maximum of 4 mm at the 2-week visit to 1-2 mm in all patients over the 9-month postinjection data collection period. No adverse visual outcomes were noted. Tonic pupil is an infrequently reported complication of BTX-A injection for strabismus. The experience of our investigator group suggests the need for careful injection technique and thorough preinjection counseling.

Publication types

  • Multicenter Study
  • Observational Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Botulinum Toxins, Type A / adverse effects*
  • Child
  • Child, Preschool
  • Esotropia / drug therapy*
  • Female
  • Humans
  • Infant
  • Injections, Intramuscular
  • Male
  • Neuromuscular Agents / adverse effects*
  • Oculomotor Muscles / drug effects
  • Pilot Projects
  • Tonic Pupil / chemically induced*
  • Tonic Pupil / diagnosis


  • Neuromuscular Agents
  • Botulinum Toxins, Type A