A study published in the International Journal of Dermatology written by Duygu Erdil MD and colleagues measured the melanin index (MI) before and 15 days after a uniform dose of onabotulinumtoxinA injections to the forehead, glabella, and crow’s feet region in 31 patients of mean age 39 years.
These patients were mainly females with Fitzpatrick’s skin type 1 to 3. The researchers noted a significant reduction in the forehead and upper face MI at 15 days.
Explaining the study background, researchers said that Botulinum toxin injection is the most commonly used cosmetic procedure for treating dynamic wrinkles. It also has a lightening effect on the skin. They elaborated further that this effect is due to muscle innervation blockage. Still, there is a lack of data on quantifying changes in the number of melanin levels.
To research this background, researchers included 31 patients who presented to the clinic of a tertiary hospital for the treatment of wrinkles using botulinum toxin injection.
The sites where the injection was injected were the patient’s forehead, glabellar, and crow’s feet region. Mexameter® MX 18 was used to measure the melanin index (MI).
The study results could be summarised as follows:
- Following botulinum toxin treatment, there was a decrease in the forehead and upper face MI.
- The upper face total baseline MI was lower in the Glogau 1 group than Glogau 2 group.
- The forehead 15th-day MI was lower in the Glogau 1 group than in the Glogau 2, 3, and 4 groups.
They discussed that applying Botulinum toxin to healthy skin causes facial skin lightening by reducing MI in wrinkle treatment.
According to our study findings, the decrease was more pronounced in the forehead. This region is the most vulnerable to sun exposure, they said.
Younger people (Glogau type 1 group) benefit more from this lightning effect.
Neuromodulators may promote facial lightening, especially in those with milder photoaging, although additional research with longer follow-up time is needed.