Photogrammetric Analysis of Palpebral Fissure Dimensions and its Position in Malaysian South Indian Ethnic Adults by Gender

Abstract

Background:

Anthropometric data describing the palpebral fissure and its position is available for various populations. Unfortunately there is no data available for Malaysian South Indian.

Aim:

The present study was undertaken to determine the normative values for Malaysian South Indian according to gender.

Materials and Methods:

Anthropometric measurement was done on standardized photographs taken from 300 MSI aged 18-26 years. The parameters were measured using computerized software.

Results:

Significant sexual difference was observed in all parameters except canthal index, which includes palpebral fissure width (male, 30.9 mm; female, 29.62 mm), palpebral fissure height (male, 11.06 mm; female, 11.48 mm), palpebral fissure inclination (male, 4.72°; female, 7.04°), outercanthal distance (male, 97.15 mm; female, 91.78 mm), interpupillary distance (male, 68.09 mm; female, 63.6 mm), intercanthal distance (male, 34.1 mm; female, 32.77 mm), and canthal index (male, 35.22 mm; female, 35.86±4.44 mm).

Conclusions:

Sexual dimorphism was found in all parameters. Comparison of our results with other studies revealed the variation and similarities in key parameters. Establishing normative values and understanding the facial morphology of different ethnic groups is important in designing the treatment planning for an aesthetic oculoplastic procedure.

Introduction

Anthropometry is a quantitative scientific method to analyze and define the dimensions, position, and proportion of the facial features. Orbital region anthropometry in the present study includes the measurement of dimensions of palpebral fissure: Palpebral fissure height (PFH), palpebral fissure width (PFW), and palpebral fissure inclination (PFI), position intercanthal distance (ICD), outer canthal distance (OCD), interpupillary distance (IPD), and its proportion canthal index (CI).These measurements play an important role in the clinical practice for evaluation and surgical treatment of craniofacial deformities. Ever since the period of the Egyptians to renaissance, various concepts have been proposed to describe ideal facial proportion. But the credibility of these aesthetical standards diminished because of interracial variation of facial morphology. So it is obvious that a single aesthetical standard may not be suitable to all ethnic groups.[1,2] The harmonious relationship and balanced proportion of facial features are considered as important components of facial attractiveness. Based on the concept of averageness is beauty, the mean values of these components derived from large group of population could be very useful for surgeons to modify the disproportionate relationship and restore the core ethnical features in harmonizes relationship.[3]

Normal average values regarding orbital and periorbital region have been reported for various populations.[1–19] Malaysian South Indians (MSI) were descendants from South India, who belong to the Dravidian race. Dravidians are one of the non-Aryan races of South East Asia and are distributed mainly in Sri Lanka, Singapore, Malaysia and South India. Since then there is no scientific data in the literature available specifically for MSI ethnic adults, we analyzed the dimension and position of eye fissure using photogrammetric measurements to generate average values for MSI.

Materials and Methods

This study was approved by the Manipal University ethics committee (UEC/58/2010). Informed written consent was obtained from all the participants prior to the beginning of the study.

Subjects

Around 303 MSI ethnic medical students aged between 18 and 26 years at Manipal University were included in the study, out of which 300 subjects (150 male and 150 females) were evaluated. Three subjects were excluded from the study because of mixed ethnic origin. Anthropometric Land marks [Figure 1]: The following landmarks: Exocanthion (ex), endocanthion (en), palpebrale superius (ps), palpebrale inferius (pi), and center of pupil were identified on the subjects with care and then the stickers with a diameter of 3 mm were placed on the landmarks (ex, en, ps, and pi).

Figure 1.

Anthropometric landmarks: Exocanthion (ex), endocanthion (en), palpebrale superius (ps), palpebrale inferius (pi), and center of pupil

Photographic set up

The photographic set up consisted of a SLR camera (Cannon model EOS 1000 D) with inbuilt grid feature manufactured by Canon India Pvt. Ltd., New Delhi, India. The camera was mounted on a tripod for stability and to correct the height of the camera according to subject's body height. The grid feature was used to align the camera in the axial plane to the subject's eyes. Subjects were positioned in front of a blue background at a distance of 51 inches from the camera, with head in natural head position and eyes open in primary gaze. A millimeter scale was framed along the side of the subject to do the measurement at life size, followed by which photograph was taken in frontal view.

Measurements

PFH (ps-pi), PFW (en-ex), PFI angle between intersecting lines, from the horizontal reference line, drawn through the ex and en), intercanthal (en-en), outercanthal (ex-ex), interpupillary (between the centre of two pupil), and canthal index was calculated as ICD/OCD×100 [Figure 2].

Figure 2.

Palpebral fissure measurements. PFW=ex-en; PFH=ps-pi; PFI=angle between intersecting lines, from the horizontal reference line, drawn through the ex to en. Canthal (medial and lateral) and interpupillary distances measurements. OCD=ex-ex; IPD=Distance between the center of pupil and ICD=en-en

Analysis

The standardized digital image was imported to a Java-based image processing program (Image J 1.43). Two examiners independently calculated all the measurements between the anthropometric landmarks using Image J analyzer software. The mean of the two examiners’ values was used. A third reading was taken if the initial two measurements showed a large discrepancy, and the two closer readings were then considered.

Statistical analysis

The statistical analysis was performed using standard computer software (SPSS for windows version 14.0, SPSS Inc., Chicago, IL, USA). The outcome variables were presented as mean and SD. Independent t test was done to test the difference between male and female. Values of P<0.05 were considered as significant.

Results

The mean, standard deviation, confidence interval SD, and CI of all variables are shown in Table 1. Statistical sexual difference was found for all the measured parameters [Figure 2]. The mean value of PFW was 30.91±1.82 mm in males and 29.62±2.21 mm in females. The mean value of PFH was 11.06±1.60 mm in males and 11.48±1.82 mm in females and the PFI was 4.71±2.39° in males and 7.05±3° in females. The average OCD for male and female were 97.15±5.95 mm and 91.78±5.82 mm, respectively. The average IPD for male and female were, 68.09±3.14 mm and 63.6±3.08 mm, ICD for male and female were, 34.1±3.51 mm and 32.77±3.22 mm. CI was 35.22±4.16 mm in males and 35.86±4.44 mm in females with no significant difference.

Table 1.

Comparison of all measurement according to gender in Malaysian South Indian population

Discussion

A youthful eye is one of the outstanding features of the upper face which plays an important role in ethnic identification. Its dimension and position varies, because of anatomical difference in periorbital features among races. In the present study we compared our results with other studies done on Africans, Caucasian, Middle Eastern, and Asian population, which revealed the variation and similarities in certain key parameters. In our study PFH was greater in females (11.48 mm) than the males (11.06 mm). In contrast, Preechawai[4] reported higher values for males (10.2 mm) thanin females (9.5 mm) in Thai-Malays and interestingly he reported identical values for both the sexes (9.5 mm) in Thais. The female mean value of PFH in MSI and Indians were similar, but lower in other population. Preechawai reported[4] mean values for Chinese (male, 9 mm; female, 9.2 mm). In Turks, Bozkir et al.[5] reported a mean value of 10.3 mm for males and 10.4 mm for females subjects. Price et al.[6] reported lower mean values (male, 9.8 mm; female, 9.5 mm) for African Americans and White Americans (male, 9.4 mm; female, 10.3 mm). Ngeow et al.[7] reported a mean value of 10.1 mm for males and 10.5 mm for females in Malaysian Indians. Takahagi et al.[8] reported extremely lower values in Nikkei's (male, 6.86 mm; female, 8.84 mm). Patil et al.[9] reported highest mean values for both sexes (male 12.3 mm; female 11.7 mm) in Indians.

PFW in MSI was larger for males (30.91 mm) than for females (29.62 mm) the result was at variance with the Farkas et al.[1] observation in Croatian (male, 30.5 mm; female, 38.3 mm) and Polish (male, 34 mm; female, 36.4 mm). Interestingly Farkas et al.[1] found wide variability in the mean values between male (37.2 mm) and female subjects (24.4 mm) in Iranians. The values reported by Ngeow et al.[7] (male, 30.7 mm; female, 29.6 mm) in Malaysian Indian, Farkas et al.[1] in Turks (male, 30.6 mm; female, 29.8 mm), and Japanese (male, 30.7 mm; female, 29.2 mm) were similar to MSI. Kunjur et al.[2] reported lower values for both sexes (male, 27.6 mm; female, 26.5 mm) in Whites and Chinese (male, 28.8 mm; female, 26.8 mm). In Nigerian population extremely higher values were reported by Jaja et al.[10] (male, 42.7 mm, female, 41.7 mm) for Kalaberi and Olidopa et al.[11] (male, 38.1 mm; female, 36 mm) for I jaws ethnic group. In Europeans, higher values were reported by Farkas et al.[1] for Croatians (female 38.3 mm), Polish (female 36.4 mm) and Portuguese (male 38.1 mm). The lowest mean value was reported by Farkas et al.[1] in Iranians (female 24.4 mm).

MSI showed Mongloid type of palpebral fissure with more obliquity in female (7.05°) compared with male (4.71°). In contrast, higher mean value was reported for males than for females by Kunjur et al.[2] in Indians (male, 2.7°; female, 1.2°), and Takahagi et al.[8] in Nikkei's (male, 7.13°; female, 6.11°). Extremely higher mean value were reported by Takahagi et al.[8] for Japanese (male, 6.62 mm; female,7.8 mm), Hanada et al.[12] for PFI in Japanese (9.39°), Indians (9.64°), and significantly lesser PFI for the Whites (4.60°). Lower PFI mean values were reported by Kunjur et al.[2] in Indians (male, 2.7°; female, 1.2°).

Kulkarani et al.[13] suggested that IPD is an accurate measurement for hypertelorism. The OCD measurements are usually affected by the surrounding soft tissues like epicanthic fold. The ICD may be increased due to broad nasal bridge. ICD in MSI showed higher values for males (34.1 mm) than for females (32.77 mm). In variance higher values were reported for females in Kalaberi (male, 18.5 mm; female, 20.7 mm),[10] Isteriki (male, 33 mm; female, 35 mm),[14] Whites[2] (male, 32.7; female, 33.3), Polish[1] (male, 30.3 mm; female, 33.6 mm), and in Thais[4] (male, 30.9 mm; female, 32.6 mm). Among the African ethnic groups, Oyinbo et al.[15] reported extremely greater mean values for males in I jaws (male, 42.37; female, 39.05). In north Asian groups, Japanese male (38.85 mm),[1] Chinese female (36.4 mm)[2] mean values were higher. MSI, mean value of the both sexes were identical to Russians[1] (male, 34.2 mm; female, 32.7 mm) and Malays[16] (male, 33.9 mm; female, 32.5 mm). In Indians, identical values were reported by Farkas et al. for males (34.1 mm)[1] and Patil et al.[9] for females (32.7 mm). Nagle et al.[17] reported smaller values in both sexes of Latvian population (male, 29.1 mm; female, 26.6 mm). In Middle Eastern groups, the values were smaller in both sexes (male, 27.3 mm; female, 24.6 mm) of Iranians population.[1]

The average value of OCD was greater in males (97.15 mm) than compared with female (91.78 mm) in MSI. In contrast, higher values for females was found in Slovakia (male, 101 mm; female, 104 mm), Polish (male, 90.2 mm; female, 93.8 mm),[1] and south Nigerian ethnic groups of I jaws (male, 111 mm; female, 119.6 mm).[11] The OCD was higher in Africans, Slovakia, and Latvians, lower in Middle Eastern and Thai population. Olidapo et al.[14] reported higher value for both sexes (male, 131 mm; female, 121 mm) in Urobhos ethnic groups. In Middle Eastern population, lower values were reported by Cem et al.[18] for both the sexes (male, 81.74 mm; female, 81.17 mm) in Turks and Farkas et al.[1] for Iranian females (79.8 mm). Preechawai reported lower OCD value in both the sexes in a study on four southern Thailand ethnic groups, the mean values in Thai- Chinese, Thai-Malay, and Thai-Chinese – were (male, 88.1 mm; female, 85.8 mm), (male, 91.2 mm; female, 85.2 mm), (male, 87.9 mm; female, 85.7 mm), and (male, 90.4 mm; female, 87.2 mm), respectively. Among the Caucasian population lower values were found in Czech of both sexes (male, 84.2 mm; female, 80.3 mm)[1] and higher values was found for Latvian male (106.3 mm)[17] and for Slovakia females (104.1 mm).[1] Only female values of our study (91.7 mm) was similar to Bulgarian female (91.9 mm).[1]

In our study, the male had wider IPD than the female subjects with significant sexual differences (males, 68.09 mm; females, 63.6 mm). Higher mean values were reported for both the sexes (male, 69.8 mm; female, 66.4 mm) in I jaws of south Nigeria[11] and in Koreans (males, 69.4 mm; females, 66.6 mm).[19] The IPD distance was wider in MSI compared with Thais (male, 61.3 mm; female 59.5mm),[4] Turkish (male, 63.9 mm; female 60.8 mm),[1] Latvian (male, 63.9 mm; female, 60.4 mm).[17] Patil et al.[9] reported for both sexes (male, 64.2 mm; female, 63.1 mm).

In MSI, CI was higher in females than the males with no significant difference. The result was in variance with Oyinbo et al.[15] (male, 37.04 mm; female, 33.11 mm), Cem et al.[18] (male, 34.67 mm; female, 34.66 mm), and Nagle et al.[17] (male, 27.38; female, 26.44 mm) who reported higher values for males than females. Higher values was reported by Oyinbo et al.[15] (male 37.04 mm). Lower values were found in Latvian population.[17] An extremely lower value (male, 17.84 mm; female, 20.8 mm) was found in Kalabaris.[10] MSI, mean values of both the sexes was similar to I jaws (male, 35.92 mm; female, 35.59 mm).[11]

Conclusion

We observed sexual dimorphism in all the measurement except in CI. Comparative analysis of orbital measurements of MSI with other populations revealed the resemblances and uniqueness in the orbital morphology of MSI. PFW was similar to Malaysian Indians, Turkish, and Japanese. PFW was longer in Africans and Europeans. PFH dimension of MSI, and Indians was identical. The North Asians, Caucasians, Africans, and Turks had a narrow palpebral fissure. In North Asians and MSI had well marked PFI compared with Whites. ICD in MSI was typical to Russians, Malays, and Indians. OCD was similar to Bulgarians, wider in Africans, Slovakia, and Latvians and lesser in Middle Eastern populations. IPD was wider in MSI compared with the Thai population, Caucasians, and Indians. OCD, ICD, IPD, and CI were extremely greater among ethnic groups of the Nigerian population. The understanding of typical and atypical features among the race may be useful in paleoanthropological studies, forensic science to identify the disputed individuals, and in studies involving human facial attractiveness.