Laser scanning for the identification of repeatable landmarks of the ears and face

Objective: To determine whether or not landmarks of the ears and face could be reliably identified using a laser scanning system. Design: A single centre study with two assessors jointly agreeing the siting of the landmarks on the ear on two separate occasions from an original laser scanned image. Setting: University based research study in London, UK. Subjects: 20 subjects, 11 males, 9 females, aged 16-24 years with normal facial development. Main outcome measures: Differences were determined between the locations of landmarks on the two occasions studied. Differences were assessed for the x, y and z co-ordinates of each point. Results: The mean difference between the two sitings of 21 landmarks ranged between 0 and 0.85 mm in the x, y and z axes. With a small number of exceptions, the differences were not statistically significant. The three-dimensional mean differences between the two sitings of each landmark ranged between 1 and 2.5 mm. Coefficients of repeatability ranged between 1.6 and 7.0 mm. Conclusions: Landmarks of the ears and face from a laser scanned image can be sited consistently by two assessors. Since the landmarks can be located it should be possible to evaluate dimensional measurements of the ear and its position on the face.