Introduction

Orbit and periorbital area are essential for their cosmetic value and functional relevance. Their dimensions are of cardinal significance in ophthalmology, reconstructive and plastic surgery. These landmarks are also considered in the evaluation of racial descent because this area, with its characteristic features and proportions, is genetically determined [1]. These values also show changes with age and gender. Another importance of these measurements is the use in the manufacture of lenses and spectacles. In ophthalmology, diagnosis and management of ptosis, microphthalmia, hypertelorism, telecanthus, and other congenital and acquired dysmorphologies require these measurements. Other orbital and periorbital disorders are typically associated with specific diseases; e.g., small palpebral fissure width is associated with fetal alcohol syndrome. Anthropometry is also of importance in forensic medicine. Because of its importance, normative data for orbital and periorbital anthropometry has been studied in different races.

There are three types of periorbital anthropometry: anthropometry of the bony orbit, periorbital soft tissue, and ocular projection. Bony orbital anthropometry includes measurement of inner inter-canthal distance (ICD), outer inter-canthal distance (OICD), and inter-pupillary distance (IPD). Periorbital soft tissue anthropometry encompasses position of eyelids, eyelid skin crease, the height of eyebrows, palpebral slant angle, the position of the medial and lateral canthi, epicanthal folds, horizontal palpebral fissure/palpebral fissure width (PFW), and vertical palpebral aperture/palpebral fissure height (PFH). Additional measurements include margin reflex distances (MRD1 and MRD2) and levator function (LF). Ocular projection is used in the assessment of orbital diseases [2]. Methods used for these measurements are manual anthropometry, two-dimensional (2D), three-dimensional (3D) photogrammetry, and 3D computed tomography (3D-CT) scan [3].

The rationale of this study was to provide a normative dataset, which can serve as a reference for oculoplastic and plastic and posttraumatic surgical interventions.

The objectives of this study were to identify the orbital and periorbital anthropometric variations in patients presented to the hospital and determine the effects of age and gender on these variables.

Material and methods

Three hundred and eighty individuals aged 15 years and above visiting a hospital with problems other than the orbital and oculoplastic diseases were included. Participants with orbital, nasal, or facial disfigurement, including congenital craniofacial anomalies, previous nasal or facial surgery and trauma, high myopia, phthisis bulbi, orbital/eyelid tumors, systemic pathologies affecting facial/orbital features such as Graves’ disease and aged less than 15 years were excluded. A detailed history was taken after informed consent. Exophthalmometric value (EV) and interorbital distance (IOD) were measured [mm] on Hertel’s exophthalmometer. Inner inter-canthal distance (ICD), inter-pupillary distance (IPD) [mm], palpebral fissure width (PFW), palpebral fissure height (PFH), marginal reflex distance 1 (MRD1), marginal reflex distance 2 (MRD2), lid crease height (LC), pre-tarsal show (PTS) and levator function (LF) were recorded using a millimeter scale. The subjects were instructed to sit straight and adopt a primary gaze position with the examiner at the same eye level as the individual to be examined. A single observer with satisfactory experience was given the task. Table 1 shows parameters with their definitions.

Results

Out of 380 subjects, there were 222 females and 158 males. The mean age was 31.7 ± 13.4. Two hundred and eighty-two individuals were less than 40 years of age, and ninety-eight were 40 years and above. Significant sexual dimorphism was noted in EV, ICD, IPD, PFH, and MRD2 (significantly higher in males versus females; p > 0.05). PFH was decreased while PTS was increased in individuals of more than 40 years. Details are shown in Tables 2 and 3.

Discussion

It is a well-known fact that not only there is diversity in anthropometry among different races, but also there are age and gender variations within the same race and ethnic group [4]. We carried out this investigational survey and compared our data with other studies. A comparison of our results with some of the previous studies is shown in Table 4.

Literature shows that IPD, PFW, and ICD in African Americans (AA) are more significant than the Caucasians [6]. When we compared these values with our study, all figures were more minor than African Americans (Tab. 4). Mean EV was also greater in AA (17.83 mm) than Caucasians and Punjabis [8]. Only the PFH was greatest in white Americans, and OICD was significant in our group.

In another study, PFH was compared among Thai, Chinese, Thai-Malay, and Thai-Chinese [9]. It was 9.5, 9.0, 10.2, and 9.6 mm, respectively. PFH in our population was greater (10.04 mm) than Thai, Chinese, and Thai-Chinese but slightly lesser than Thai-Malay (10.2 mm). In the same study, the PFW, EV, and LF were more significant than our group. However, the MRD1 and LC in these ethnic groups were lesser than in our study. Another finding was the absence of an upper lid crease and an epicanthal fold in a more significant number of individuals from the Chinese population.

When the ICDs of Chinese and Koreans were compared with our study, there was a considerable difference in these values: 31.7 mm in our group vs. 36.53 mm in Chinese vs. 38mm in Koreans. In other studies, Turkish [10], Indians [11], North American whites [12], and African-Americans [12] also had lesser values of ICD than Chinese and Koreans. Iranians had the smallest ICD — 25.95 mm [7]. In a recently published data, Indians had greater PFW and PFH than the Chinese [13]. Values of PFW and PFH in our study were also greater than Chinese.

Flament et al. used 3600 photographs of women’s eyes from six different regions of the world (Africa, China, Hispania, India, Japan, and Caucasians). The study showed that the Asians had a more oblique orientation of their eyes versus the horizontal inter-pupillary line. In all ethnicities, aging caused significant changes in the height and orientation of the eyes [14].

In this particular study, EV, ICD, IPD, PFH, and MRD2 were significantly higher in males versus females (p > 0.05). In Chinese, males had larger orbital values than females except for PFH. This was in contrast to our study in which PFH was significantly higher in males than females. Another difference was that PFW was substantially larger in Chinese females, which was not significantly different in our study.15,16 Turkish study showed sexual dimorphism similar to our research [17, 18]. In a Nigerian study, the gender difference was observed only for brow height (p = 0.029) [19].

Contrary to our results, in an Indian study, there was a statistically significant difference in the PFW (p < 0.001) and OICD (p < 0.05) between males and females [20]. However, there was no significant difference in the PFH (p > 0.05) and ICD (p > 0.05) between the two sexes in Indians but in our study, PFH was significantly higher in males.

According to one study, EV decrease with age (average reduction of 0.06 mm/year) [20]. In our study, there was a significant decrease in PFH after 40 years but not in EV. PTS also showed increased values after 40 years [9, 20]. Both of these findings are explained by senile ptosis.

The strength of this study is that we analyzed 11 parameters and compared them with research from other parts of the world. More data from different parts of Pakistan is needed to complete a dataset from the Pakistani population. The limitation of this study is that the measurements were taken manually with a chance of human error. Further studies using CT scan and photogrammetry should be done to affix the results of this study.