In most measurement sections, male value was higher than female value and the difference of the values showed statistical significance.
In the orbital width and height, the means were generally similar to Kim et al, (2016)’s data14 for orbital dimensions of Korean population. In our research, the mean orbital widths were 40.72mm (R1) and 40.68mm (L1) in males and 39.24mm (R1) and 38.96mm (L1) in females and the mean orbital heights were 36.72mm (R8) and 36.80 (L8) in males and 35.60mm (R8) and 35.72mm (L8) in females. Kim’s et al. (2016) reported that orbital widths were 42.1mm in males and 40.3mm in females and orbital heights were 38.1mm in males, 37.9mm in females.
The centre of eye lens was 16.97 ± 1.62mm in males and 16.78 ± 1.19mm in females away from the topmost point (supraorbitale) of the orbit and 23.12 ± 1.82mm in males and 21.95 ± 1.66mm in females away from the innermost point (medial orbit) of the orbit. In terms of ratios, the longitudinal value was 46% of the orbit height from the superior to the inferior and the horizontal value was 57% of the orbit width from the medial to the lateral. These data indicate that the eyeballs are located rather superolaterally in the anterior view of the eye orbit.
These results show the similar patterns as Stephan et al.14, 15 and Guyomarc’h et al.’s11 reports on other ethnic groups than Korean; Stephan et al. reported the distance from the topmost point (supraorbitale) to the cornea centre in front view was 16.9mm and from the innermost point (medial orbit) of the orbit to the cornea centre in anterior view was 20.9mm. They also reported the eyeball located in rather superolateral position in the eye orbit in anterior view. Guyomac’h et al. reported that the distance from the centre of eye lens to the topmost point is 44.1% of the eye orbit height and from the innermost point to the eye lens cents is 57.6% of the eye orbit width, which is also indicating the superolateral position of the eyeball in the anterior view of the eye orbit.17
In contrast, Kim et al. reported in previous study on Koreans that the position of the eyeball, unlike other studies, was located inferolaterally.14 It was discussed that the difference comes from the subjects’ condition; Stephan et al. researched the cadavers as sample subjects whereas Kim et al. used living subjects for the research. Guyomarc’h et al. used living subjects in supine position11 whereas the alive Korean subjects in Kim et al.’s were scanned in sitting position by CBCT (cone-beam computed tomography).14
The position of the eyeball in the eye orbit has been somewhat consistent among studies but it is necessary to maintain uniform research conditions for a more accurate comparison.
In our study, the thickness of the eye lens increased with age from 3.82 mm to 4.40 mm, consistent pattern with the previous studies; Klein et al. reported that the eye lens thickness systematically increase with age.19 Kim et al. reported that the eye lens thickness gradually increased from 3.56mm to 4.55 mm by aging.14
In the eyeball diameter, the vertical diameter (E5) of eyeball was 23.68 ± 1.18mm in males and 23.42 ± 0.73mm in females and the horizontal diameter (E6) of eyeball was 23.64 ± 1.14mm in males and 23.45 ± 1.17mm in females, which is showing approximate values from the other studies on other ethnic groups. Bekerman et al. reported that emmetropic human adult eyeball have 23.7mm of vertical diameter and 24.2mm of horizontal diameter without significant differences in different sex and age groups.20 In Guyomac’h’s report (2012), the average diameters are 24.6mm in vertical, 24.3mm in horizontal and 23.7mm in anterior-posterior although the males’ are significantly larger.11
We used correlation analysis of anthropometric measurements to determine the extrusion and position of the eyeball in the eye orbit. This approach is expected to provide more reliable information for the eye region of recreated face images. However, while the eye region has been reported to be the most informative area for distinguishing among faces,7–10, 21 fixation patterns differ by cultural background. For example, Caucasians mainly observe the region and partially mouth whereas East Asians, including Koreans, tend to observe more on the central region of the face.9, 22 This cultural difference could lead to different results in terms of face recognition for forensic analysis, as people from different cultural background may be involved in the process of forensic identification as witnesses, law enforcement members or any other observers.
Face recognition is generally believed to be related in the defining the differences of the relative size and position of the facial features within the face.23, 24 Hence, not only the interocular distance but the distances between the other facial features must also be estimated from an unidentified skull. To this end, we incorporated facial landmarks and reference planes produced in the uniform mechanism with previous studies of correlations between eyebrows/orbits and the nose/nasal aperture groove.12,13 This allowed us to reconstruct/approximate facial features based on the morphology of the unidentified skull as well as to minimize interference caused by estimations based on the features of different cultures. We are currently investigating the relevant features of the mouth and ears; once these studies are completed, an estimation method for the entire facial feature morphology of the Korean skull will be developed and tested for craniofacial reconstruction/approximation.