The outer corner
of the right eye was measured three consecutive times with
the PRIMOS Lite after placing subjects' face onto a special
PRIMOS face-held-equipment (GFMesstechnik GmbH)
and focusing the outer corner of eye on a same pattern of
the PRIMOS Lite to prevent the test area from moving. The
images adjusted to the same position each time by applying 3D
matching and were analyzed with the PRIMOS Lite software
(version 5.6E; GFMesstechnik GmbH). The measurement variable Ra (average of all heights and depths to the reference
plane) was used for wrinkle analysis as the most common
surface roughness index worldwide, which represents the
maximal mathematical average of the profile within the entire
measurement range. The Ra value decreases with a lower depth
of wrinkles, indicating that skin wrinkles were improved.