Injection treatment of Squint with Botox/Bupivacaine under EMG Guidance

  • Nearly 15% patients with squint can be given a small, painless injection of a drug called Botox ± Bupivacaine to correct squint.
  • This injection is best given under an electromyogram (EMG) control.
  • It is given in the eye muscle (pink in the figure), Not in the EYE!
  • The injection takes only 2 minutes to give and it is painless.
  • An EMG can identify the eye muscle. It also informs the doctor about the ideal location within the eye muscle where the injection will be safe and more effective.
  • The effect starts in 6 hrs to 48 hrs. Maximum effect stays for 2-4 weeks. The injection effect slowly disappears in 6 weeks to 12 weeks when the squint is corrected.
  • Any side effect due to injection is usually fully reversible.


  • Initially there is an over correction.
  • Some patients may need more than 1 injections.
  • Squint surgery if necessary (IN 50%), can be performed later with full safety and efficacy after the injection.
  • Botox is costly. To reduce the cost it may be used in batch / salami (repeatedly from same vial over 4 -6 weeks).
  • When not used fresh, chances of reduced effectiveness &/or infection is present.
  • In young children, injection can be given under general anesthesia.
  • Main purpose of giving injection is to try to avoid a surgery/treat double vision in adults.

Safety and Side-effects

Under EMG control; side effects are rare <1%
Commonest, reversible (7-10 days) side effect: drooping of lids 20%
Infection and globe perforation 0.001%


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