High versus low concentration botulinum toxin A for benign essential blepharospasm: does dilution make a difference?

Area of Science:

• Ophthalmology
• Neurology

Background:

• Benign essential blepharospasm (BEB) is a neurological disorder characterized by involuntary eyelid closure.
• Botulinum toxin A is a common treatment for BEB, but optimal concentration remains debated.

Purpose of the Study:

• To compare the efficacy and side effects of concentrated versus dilute botulinum toxin A in treating BEB.
• To assess patient-reported outcomes including pain, bruising, redness, complications, and symptom relief duration.

Main Methods:

• A prospective randomized clinical trial involving 16 BEB patients.
• Bilateral injections with low (10 U/ml) and high (100 U/ml) concentrations of botulinum toxin A.
• Patient surveys on pain, bruising, and redness post-injection, and complications and relief duration at follow-up.

Main Results:

• A statistically significant reduction in pain scores was observed with the high concentration (1.94) compared to the low concentration (4.59).
• No significant differences were found in bruising, redness, injection-related complications (ptosis, diplopia, tearing, dry eye), or duration of symptom relief between concentrations.
• Patients did not report a significant preference for either dilution based on overall outcomes.

Conclusions:

• Higher concentration botulinum toxin A (100 U/ml) significantly reduces perceived pain in BEB treatment compared to lower concentrations (10 U/ml).
• Efficacy and complication profiles were similar between the tested concentrations, suggesting pain reduction is the primary benefit of higher concentrations.