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.
Remember
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
