Anthropometry of Eyelid and Orbit in Four Southern Thailand Ethnic Groups
* Department of Ophthalmology, Faculty f Medicine, Prince of Songkla University, Hat Yai, Songkhla, Thailand
Affiliation : Passorn Preechawai MD*
Objective : To study the basic eyelid and orbital measurement in the four main ethnic groups of southern Thailand.
Material and Method: The basic eyelid and orbital surface anatomy of 101 normal subjects aged 20-40 years old were
measured in the four ethnic groups of which the majority of people in southern Thailand belong to: Thai, Chinese, Thai-Malay,
and Thai-Chinese.
Results : Of the 101 subjects, 51 were male and 50 were female. Each ethnic group had at least 12 normal subjects.
Male-female data were analyzed separately and compared between groups. The palpebral fissure heights in Thai, Chinese,
Thai-Malay, and Thai-Chinese males were 9.5, 9.0, 10.2 and 9.6 mm respectively, which demonstrated statistically significant
differences between Thai-Malay versus Thai, and Thai-Malay versus Chinese. The palpebral fissure lengths were 30.4, 29.8,
30.5 and 30.5 mm, but without statistically significant differences. The marginal reflex distances were 3.2, 2.8, 3.7 and 3.1 mm
respectively with a statistically significant difference only between Thai-Malay versus Chinese. The levator functions were
15.2, 15.2, 15.3 and 15.2 mm. The upper lid creases were 7.1, 4.0, 6.6, and 4.4 mm, statistically significantly different in Thai
versus Chinese, Thai versus Thai-Chinese and Chinese versus Thai-Malay. The Hertel exophthalmometer measurements
were 15.4, 16.3, 16.6 and 15.9 mm without statistically significant differences. The female measurements were overall similar
to the male measurements, with some parallel differences between the groups. The eyebrow position in this age group was
mostly at and above the orbital rim in both genders and all ethnic groups. An absence of upper lid crease and an epicanthal
fold were found in significantly greater numbers in the Chinese group compared to the others, while parallel lid crease was
significantly found in greater numbers in the Thai-Malay group than in the others.
Conclusion : Different eyelid characteristics in different ethnic groups are an important feature to note when planning for
eyelid surgery. As there is a wide range of ethnic groups in Asia, with many differences in eyelid characteristics, it is important
for the ophthalmologist to be aware of and understanding these anatomical variations in clinical assessment and treatment
in Asians.
Keywords : Anthropometry, Surface anatomy, Palpebral fissure, Marginal reflex distance, Levator function, Exophthalmometric measurement
