The quantitative assessment of wrinkle depth: turning the microscope on botulinum toxin type A

This prospective study was designed to produce a quantitative model for wrinkle depth assessment, and to compare scientific and clinical methods of evaluation, in the context of botulinum toxin type A treatment. Ten patients were assessed at baseline and 3 weeks after treatment using silicone masks and standardized photography in forehead, glabellar, and lateral canthal areas, at rest and during maximal expression. Wrinkle depth was measured on masks using multiphoton microscopy. Clinical improvement was judged by a panel of observers according to the Hay scale. There was a statistically significant improvement in wrinkle depth after treatment in all areas. Dynamic rhytides demonstrated greatest improvement, notably in the forehead (89% reduction). The objective improvement in static rhytides (43%-56%) has not previously been demonstrated. Clinical evaluation was less accurate than scientific methodology for static lines. This model may have a place in comparing products or treatment regimes, particularly when changes are subtle.