Further Evidence on the Anatomical Placement of the Human Eyeball for Facial Approximation and Craniofacial Superimposition*

Abstract: Recently a small sampled cadaver study (n = 4) suggested that the human eyeballs are placed closer to the orbital roof and lateral orbital wall as first reported in the anatomical literature many years previously. This contrasts with central positioning of the eyeball within the orbit as advocated by the facial approximation literature. Given the limits of such small samples, this study re-examined globe position in nine new cadavers to help clarify which relationship is accurate. The results essentially confirm prior empirical findings except that the mean lateral divergences from the orbit center were found to be larger—the eyeball was found to be “displaced” 1.4 mm superiorly and 2.4 mm laterally. Medians calculated across all 13 cadavers from this study and the above-mentioned recent report refine these measurements to 1.4 and 2.3 mm respectively. Globe projection values were identical to those observed for living individuals (c. 16 mm).     

Facial approximation: globe projection guideline falsified by exophthalmometry literature

The projection of the cornea from the bony orbit has been determined, in facial approximation, by centrally locating the eyeball in the orbit and positioning the cornea so that its most anterior point falls in line with a tangent dropped from the mid-superior to the mid-inferior orbital rim. However, there appears to be no scientific evidence to justify this guideline; yet, there have been numerous studies that measure globe projection in living subjects, from the lateral orbit using an exophthalmometer. The aim of this study was to determine if the traditional facial approximation guideline is consistent with the exophthalmometry literature. MRI research shows that corneal projection is underestimated using the traditional facial approximation guideline. An underestimation is also strongly supported by statistical comparisons of globe projection measures taken using more traditional instruments (e.g., Hertel's exophthalmometer) to skull morphology (p < 0.006). It is suggested that the traditional facial approximation guideline not be used in future facial approximations since it appears to under-predict anterior globe projection by 4 mm on average. It is also suggested that average exophthalmometer values be used until more accurate and precise ways of determining globe projection have been determined.     

Building faces from dry skulls: are they recognized above chance rates?

Methods of facial approximation have successfully aided the identification of deceased individuals. Successes may be due to either accurate facial approximation techniques or chance. This study aims to determine if any of 16 facial approximations, built using standard techniques, are sufficiently accurate to produce correct identifications of target individuals above chance. Four skulls were approximated using four commonly used methods of facial approximation. The resulting 16 facial approximations were judged by 37 assessors of varying ages. Assessors attempted to identify the target individual of each facial approximation from a face pool of ten photographed faces. Only one facial approximation resulted in true positive identification rates above chance at statistically significant levels. It is concluded that it is rare for facial approximations to be sufficiently accurate to allow identification of a target individual above chance. Since 403 incorrect identifications were made out of 592 identification scenarios, facial approximation should be considered to be a highly inaccurate and unreliable forensic technique. These results suggest that facial approximations are not very useful in excluding individuals to whom skeletal remains may not belong. Evidence from this experiment supports suggestions by others that facial approximation should be used in forensic science when all other methods of identification have failed and only to provide tentative identification.     

Eyeball Position in Facial Approximation: Accuracy of Methods for Predicting Globe Positioning in Lateral View

This study measured the accuracy of traditional and validated newly proposed methods for globe positioning in lateral view. Eighty lateral head cephalograms of adult subjects from Central Europe were taken, and the actual and predicted dimensions were compared. The anteroposterior eyeball position was estimated as the most accurate method based on the proportion of the orbital height (SEE = 1.9 mm) and was followed by the “tangent to the iris method” showing SEE = 2.4 mm. The traditional “tangent to the cornea method” underestimated the eyeball projection by SEE = 5.8 mm. Concerning the superoinferior eyeball position, the results showed a deviation from a central to a more superior position by 0.3 mm, on average, and the traditional method of central positioning of the globe could not be rejected as inaccurate (SEE = 0.3 mm). Based on regression analyzes or proportionality of the orbital height, the SEE = 2.1 mm.     

Forensic Facial Approximation: Study of the Nose in Brazilian Subjects

Forensic facial approximation is an auxiliary method for human identification and allows facial recognition. The midface, that includes the nose, is vital for the recognition of a familiar face. The purpose of this study was to set hard tissue parameters to estimate nasal width, to test the method to estimate nasal width of Brazilians, and to analyze the relationship between nasal profile and facial type. A total of 246 computed tomography scans (183 females and 63 males) of adults were analyzed in Horos. Bone tissue measurements and facial type classification were performed on the skull scan. Nasal profile morphology was accessed through the tool 3D surface rendering. There was a difference around 3 mm from real to predicted nose through the method to estimate nasal width in Brazilians. So, the method may be used in forensic practice. Straight nose was associated with long face type.     

The placement of the human eyeball and canthi in craniofacial identification

An accurate understanding of the spatial relationships between the deep and superficial structures of the head is essential for anthropological methods concerned with the comparison of faces to skulls (superimposition) or the prediction of faces from them (facial approximation). However, differences of opinion exist concerning: (i) the position of the eyeball in planes other than the anteroposterior plane and (ii) the canthi positions relative to the bony orbital margins. This study attempts to clarify the above relationships by dissection of a small sample of adult human cadavers (N = 4, mean age = 83 years, s = 12 years). The most notable finding was that the eyeballs were not centrally positioned within the orbits as the more recent craniofacial identification literature expounds. Rather, the eyeballs were consistently positioned closer to the orbital roof and lateral orbital wall (by 1-2 mm on average); a finding consistent with the earlier anatomical literature. While these estimation errors are small ipsilaterally, several factors make them meaningful: (i) the orbital region is heavily used for facial recognition; (ii) the width error is doubled because the eyes are bilateral structures; (iii) the eyes are sometimes used to predict/assess other soft tissue facial structures; and (iv) the net error in facial approximation rapidly accumulates with the subsequent prediction of each independent facial feature. While the small sample size of this study limits conclusive generalizations, the new data presented here nonetheless have immediate application to craniofacial identification practice because the results are evidence based. In contrast, metric data have never been published to support the use of the central positioning guideline. Clearly, this study warrants further quantification of the eyeball position in larger samples and preferably of younger individuals.     

Facial Soft Tissue Thickness Among Three Skeletal Classes in Adult Pakistani Subjects

Different facial reconstruction methods rely on the average facial soft tissue thickness values provided in previous studies. Facial soft tissue thickness is influenced by the age, sex, and ethnicity of the individual. The aim of the present study was to determine facial soft tissue thickness of adult Pakistani subjects with different facial morphology. A total of 166 subjects were categorized into three skeletal classes (based on convex, straight, or concave facial profile) employing the classification system used in orthodontics. Facial soft tissue thickness was determined at ten midline points on lateral cephalograms. Significant differences in facial soft tissue thickness were present at glabella, labrale superius, stomion, and labiomentale in males and at labrale superius, labrale inferius, labiomentale, and pogonion in females among different skeletal classes. The current study suggests that the skull morphology-related variations in facial soft tissue thickness should be considered during facial reconstruction to achieve accurate results.     

Do resemblance ratings measure the accuracy of facial approximations?

Since forensic facial approximations are used to promote recognition of a deceased person, an accurate forensic facial approximation (FFA) should be easily recognized as the person to whom the skull belonged (target individual). However, the accuracy of FFAs has been previously assessed by the direct comparison of an FFA to the corresponding target individual for similarity (i.e., a resemblance rating). Resemblance ratings may not indicate a facial approximation's accuracy since the resemblance of non-target individuals is not accounted for. This experiment tests the validity of using resemblance ratings to assess the accuracy of FFAs. The study indicates that there is no statistically significant difference between: (a) resemblance ratings of FFAs to target individuals and (b) resemblance ratings of FFAs to individuals incorrectly identified as the target individual. It is concluded that it is not possible from resemblance ratings to determine the accuracy and/or quality of a facial approximation since a non-target individual may receive a resemblance rating equal to, or higher than, the target individual.     

Is Dwight Right? Can the Maximum Height of the Scapula Be Used for Accurate Sex Estimation?*

Abstract: This paper presents data from a sample of 803 individuals (308 females and 495 males) from the Hamann‐Todd collection testing Dwight’s century‐old assertion that maximum height of the human scapula can be used for sex estimation—males being larger than 170 mm, females falling below 140 mm. The results of this project show Dwight’s method has high accuracy when scapular height falls either above or below the sex specific demarcation points (96.81%), but a vast majority of both males and females fall in between. The overall accuracy of the method is just 29.27%. By empirically demonstrating the limited usefulness of Dwight’s technique, the author hopes the rote republication of this method in introductory texts on the subject will cease, and draw attention to the need for multiple methods of sex estimation as a response to the overlap in both size and shape between males and females.     

Estimating eyeball protrusion from body height, interpupillary distance, and inter-orbital distance in adults

Eyeball protrusion is one characteristic that must be assessed/predicted in craniofacial identification methods of skull-face superimposition and facial approximation. Previously it has been suggested that average exophthalmometry values, as measured on living individuals, should be used. However, it is unknown if proptosis prediction can be improved beyond the accuracy obtained when using mean values. Some authors have suggested that relationships between exophthalmos, height, interpupillary distance, and interorbital distance exist and it has been reported that these latter variables can be used to estimate eyeball projection. However, crucial tests are yet to be conducted. This study measures these variables and tests the accuracy of exophthalmometry means, a previously proposed prediction equation, and newly derived regression equations to determine which methods provide the best results. Data indicate that variation in exophthalmos is fairly small and as such prediction from other variables, like body height, are weak; thus, exophthalmometry means currently offer the best practical method of prediction. It should be noted that up to 2 mm error from either side of the mean is expected for 68% of cases.     

In vivo facial tissue depth measurements for white British children

This paper reports the results of a study of facial tissue depth measurement in White British children of both sexes, aged between 11 and 18 years. The purpose of this research was to increase the information available upon tissue depth data for children, primarily for use in forensic facial reconstruction. Facial tissue depths were measured at 21 anatomical points using ultrasonic echo-location. The mid-philtral, upper lip border and lower lip border points showed consistently larger tissue depths in the males than the females, and the zygomatic attachment showed consistently larger tissue depths in the females than the males. The males showed a general increase in tissue depth with an increase in age at all the mid-line facial points and the cheek points. The females showed increased tissue depth with age at all the points except the infra-orbital, lateral orbital, mid-zygomatic arch and mid-mandibular points. A table of mean tissue depths was developed for males and females divided into two-yearly age groups.     

In Vivo Facial Tissue Depth for Canadian Aboriginal Children: A Case Study from Nova Scotia,Canada

This study examines facial tissue depth in Canadian Aboriginal children. Using ultrasound, measurements were taken at 19 points on the faces of 392 individuals aged 3–18 years old. The relationships between tissue thickness, age, and sex were investigated. A positive linear trend may exist between tissue thickness and age for Aboriginal females and males at multiple points. No points show significant differences in facial tissue depth between males and females aged 3–8 years old; seven points show significant differences in facial tissue depth between males and females aged 9–13 years old; and five points show significant differences in facial tissue depth between males and females aged 14–18 years old. Comparisons were made with White Americans and African Nova Scotians. These data can assist in 3‐D facial reconstructions and aid in establishing an individual's identity. Previously, no data existed for facial tissue thickness in Canadian Aboriginal populations.     

Assessing facial approximation accuracy: how do resemblance ratings of disparate faces compare to recognition tests?

In the past, the accuracy of facial approximations has been assessed by resemblance ratings (i.e., the comparison of a facial approximation directly to a target individual) and recognition tests (e.g., the comparison of a facial approximation to a photo array of faces including foils and a target individual). Recently, several research studies have indicated that recognition tests hold major strengths in contrast to resemblance ratings. However, resemblance ratings remain popularly employed and/or are given weighting when judging facial approximations, thus indicating that no consensus has been reached. This study aims to further investigate the matter by comparing the results of resemblance ratings and recognition tests for two facial approximations which clearly differed in their morphological appearance. One facial approximation was constructed by an experienced practitioner privy to the appearance of the target individual (practitioner had direct access to an antemortem frontal photograph during face construction), while the other facial approximation was constructed by a novice under blind conditions. Both facial approximations, whilst clearly morphologically different, were given similar resemblance scores even though recognition test results produced vastly different results. One facial approximation was correctly recognized almost without exception while the other was not correctly recognized above chance rates. These results suggest that resemblance ratings are insensitive measures of the accuracy of facial approximations and lend further weight to the use of recognition tests in facial approximation assessment.     

Measuring the accuracy of facial approximations: a comparative study of resemblance rating and face array methods

The success of facial approximation is thought to depend, at least in part, upon the "accuracy" of the constructed face. However, methods of accuracy assessment are varied and this range in methods may be responsible for the disparate results reported in the literature. The aim of this study was to determine if the accuracy results of one facial approximation were comparable across two different assessment methods (resemblance ratings and simultaneous face array tests using unfamiliar assessors) and if resemblance ratings co-varied with recognition responses. True-positive recognition performance from the facial approximation was poor (21%) while resemblance scores using the same facial approximation were moderately high (3 out of 5 on a five-point scale). These results are not, therefore, consistent and indicate that either different variables are being evaluated by the methods, or the same variable is being examined but with different weight/calibration. Further resemblance ratings tests of the facial approximation to three foil faces from the face array revealed that resemblance scores were similar irrespective of which face was compared, and did not closely correspond with the degree of recognition performance. This was especially the case for isolated comparisons of single faces to the facial approximation. Collectively, these results indicate that resemblance ratings are: (i) insensitive measures of a facial approximation's accuracy; and (ii) inconsistent with results of unfamiliar simultaneous face-array recognition results. These data suggest that familiar and unfamiliar recognition tests should be given increased weight in contrast to current resemblance rating tests.     

中国土家族人群头面部软组织厚度的测量

目的测量中国土家族人群头面部软组织厚度。方法156名中国湖南西部土家族成年男女(男80,女76),经拍摄头面部侧位X线片,选取正中矢状面5个部位上的10个点,测量其软组织厚度,并对所得数据进行统计学处理。结果中国土家族成年人群头面部10个点的软组织厚度测量值,男性在(3.46±0.09)mm~(9.11±0.14)mm范围,女性在(3.29±0.16)mm~(9.05±0.18)mm;除鼻下点外(男性9.06mm±0.15mm,女性9.02mm±0.19mm),男女性之间各点均有显著性差异,且下面部软组织厚度较上面部大。结论土家族成年男女性头面部软组织厚度存在着性别差异和年龄差异。     

The Lateral Angle Revisited: A Validation Study of the Reliability of the Lateral Angle Method for Sex Determination Using Computed Tomography (CT),

This article presents the results of a validation study of a previously published method of sex determination from the temporal bone. The purpose of this study was to evaluate the lateral angle method for the internal acoustic canal for accurately determining the sex of human skeletal remains using measurements taken from computed tomography (CT) scans. Previous reports have observed that the lateral angle size in females is significantly larger than in males. The method was applied to an independent series of 77 postmortem CT scans (42 males, 35 females) to validate its accuracy and reliability. The mean lateral angle of the internal acoustic canal was found to be larger in females (46.5°) than in males (43.4°). However, the difference was not statistically significant and the sex differences reported in previous studies were not substantiated. In light of the observed results, the lateral angle method appears to be of minimal practical use in forensic anthropology and archeology.     

An accuracy assessment of forensic computerized facial reconstruction employing cone-beam computed tomography from live subjects

The utilization of 3D computerized systems has allowed more effective procedures for forensic facial reconstruction. Three 3D computerized facial reconstructions were produced using skull models from live adult Korean subjects to assess facial morphology prediction accuracy. The 3D skeletal and facial data were recorded from the subjects in an upright position using a cone-beam CT scanner. Shell-to-shell deviation maps were created using 3D surface comparison software, and the deviation errors between the reconstructed and target faces were measured. Results showed that 54%, 65%, and 77% of the three facial reconstruction surfaces had <2.5 mm of error when compared to the relevant target face. The average error for each reconstruction was -0.46 mm (SD = 2.81) for A, -0.31 mm (SD = 2.40) for B, and -0.49 mm (SD = 2.16) for C. The facial features of the reconstructions demonstrated good levels of accuracy compared to the target faces.     

CHN骨龄在司法鉴定中的应用价值

目的探讨CHN(中国人手腕骨发育标准CHN法)骨龄在司法鉴定中的应用价值,分析影响其准确性的因素及相关问题。方法对522例年龄鉴定者,均选用不同曝光值拍摄两张左手腕部正位X线片,并加照两次斜位片。使用CHN法测评骨龄。结果522例中男性489例,女性33例。男性达CHN骨龄最高值18.4岁者129例,余平均骨龄16.5岁。女性达CHN骨龄最高值17.3岁者14例,余平均骨龄15.7岁。CHN骨龄在16.0岁以上者共388例,占约74.3%。本组资料显示多种因素影响骨龄鉴定的准确性,其中以骨龄片位置及角度的变化等影响最大。结论如能获得高质量的X线片、并能熟练使用CHN法、注意利用位置和角度的变化正确判定骨骺分级,CHN骨龄基本可满足活体年龄鉴定的需要。     

Validation of the New Interpretation of Gerasimov's Nasal Projection Method for Forensic Facial Approximation Using CT Data,

The most common method to predict nasal projection for forensic facial approximation is Gerasimov's two‐tangent method. Ullrich H, Stephan CN (J Forensic Sci, 2011; 56: 470) argued that the method has not being properly implemented and a revised interpretation was proposed. The aim of this study was to compare the accuracy of both versions using a sample of 66 postmortem cranial CT data. The true nasal tip was defined using pronasale and nasal spine line, as it was not originally specified by Gerasimov. The original guidelines were found to be highly inaccurate with the position of the nasal tip being overestimated by c. 2 cm. Despite the revised interpretation consistently resulting in smaller distance from true nasal tip, the method was not statistically accurate (p > 0.05) in positioning the tip of the nose (absolute distance >5 mm). These results support that Gerasimov's method was not properly performed, and Ullrich H, Stephan CN (J Forensic Sci, 2011; 56: 470) interpretation should be used instead.