Facial expressions affect photo comparability

How accurate is your before and after treatment photography method? (WavebreakMediaMicro - stock.adobe.com)

Dr. Mustoe

Researchers report in a new study that 16 facial expressions and head positions significantly impact malar and jowl volumes, with smiling and frowning having the biggest effects. Facial volume changes from expressions can look like results seen from aesthetic facial rejuvenation procedures.

The authors used three-dimensional facial images of 20 subjects to quantify how 22 facial expressions and head position changes might impact volume in the mid and lower face. Researchers also identified a combination of soft tissue surface landmarks - glabella, bilateral cheilion, pogonion and laryngeal prominence - that plastic surgeons, dermatologists and others can refer to in order to standardize 3D image use.

They published their findings January 2019 in Plastic and Reconstructive Surgery.

“Currently, photography is the primary way to evaluate outcomes from aesthetic surgery for the aging face, including the many techniques for facelift, neck lift, midface lift and mini facelift,” says study author Thomas Mustoe, M.D., chief of plastic surgery at Northwestern University Hospital in Chicago. “This study provides a method for standardizing facial positioning on 3D imaging, which allows quantification of changes in facial shape and volume that was previously lacking. In the future, it will allow us to evaluate the impact of changes in technique in a way that was not previously possible. It also highlights the limitations of current deficiencies in photography which makes comparisons of before and after pictures problematic.”

Dr. Mustoe and colleagues report smiling increased malar volume by an average 13.4 mL and decreased jowl volume by an average 1.2 mL. Frowning increased jowl volume by an average 3.3 mL and decreased malar volume by an average 2.2 mL. Even a slight smile led to substantial non-linear increases in malar volume and a slight frown to such increases in jowl volume.

“Even a small smile … that raises the corner of the mouth even a millimeter has the same effect as a substantial cheek augmentation …,” the journal’s Editor-in-Chief Rod J. Rohrich, M.D., says in an accompanying video.

Among the other findings: Snarling augmented malar volume by an average 5.1 mL, while lower lip depression augmented jowl volumes by an average 3.2 mL.

Nasal flaring and periorbita of the eyelid and brow did not impact mid and lower facial volumes, so clinicians can ignore soft tissue landmarks to identify those expressions, according to the study.

Simultaneous facial expressions could confound and invalidate results, they write.

The authors use a standard protocol in their plastic surgery practice for taking and comparing pre- and post-procedure 3D facial photographs.

Like with 2D photography, they take 3D images with attention to room lighting, camera distances, angle and Frankfort plane alignment. They then superimpose their after images, aligning the photos using the 3D structure of the forehead, brow and nasal root, they write. Finally, the authors use the soft-tissue landmarks they described in the paper to confirm the two images are comparable and unaffected by even slight changes in head position or facial expression.

“Once this is confirmed, appropriate measurements and volumetric data can be obtained,” according to the authors. “As the use of 3D photography becomes more prevalent, such a method should be adopted universally to ensure the reliable comparability of photographs.”