Botox Dosing and Injection Sites for Blepharospasm
For blepharospasm, inject botulinum toxin into the pretarsal portion of the orbicularis oculi muscle using 1.25-2.5 U per site, with a typical total dose of 25-50 U per eye (12.5-25 U per side distributed across multiple injection points in both upper and lower eyelids). 1, 2
Injection Technique
Site Selection
- Target the pretarsal portion of the orbicularis oculi muscle rather than the preseptal region, as this produces significantly higher response rates (95% vs 81% success), longer duration of benefit (12.5 weeks vs 8.5 weeks), and fewer complications like ptosis 2
- Inject both upper and lower eyelids bilaterally 3, 4
- Upper lid: Place 2 injections into the pretarsal orbicularis oculi 2
- Lower lid: Place 1 injection into the pretarsal region 2
- Additional sites may include the brow and upper face if spasms extend beyond the periocular region 3
Dosing Parameters
- Standard starting dose: 12.5 U per side (25 U total per session) distributed across injection sites 4
- Typical range: 25-50 U total per treatment session 3
- For refractory cases requiring injections every 2 months despite standard dosing, supramaximal doses above 100 U per session may be considered and are well tolerated, potentially extending the interval between treatments 5
Expected Outcomes
Efficacy Timeline
- Maximum effect occurs within 5 days of injection 3
- Mean duration of benefit: 11.8-12.5 weeks with pretarsal technique 2, 3
- Repeated injections maintain similar efficacy to initial treatment 3
Treatment Response
- Success rate with pretarsal technique: 95% 2
- All patients typically receive some degree of relief 4
- Note that spasms may recur despite persistent orbicularis weakness, requiring repeat treatment 4
Safety Considerations
Common Adverse Effects
- Ptosis occurs significantly less frequently with pretarsal injections compared to preseptal technique 2
- Complications are local, mild, and transient 3
- No systemic side effects have been reported in clinical trials 3
- Dysphagia and aspiration risk can occur if toxin diffuses to swallowing muscles, particularly in patients with pre-existing neuromuscular disorders 6
Important Caveats
- OnaBoNT-A and incoBoNT-A are equally effective and should be considered for blepharospasm treatment, while AboBoNT-A is a possibly effective option 7
- Patients with combined blepharospasm and involuntary levator palpebrae inhibition respond better to pretarsal injection technique 2
- Most side effects are temporary and resolve within 3-6 months as the toxin effect diminishes 6