japanese immigration occurred mainly from 1908 to 1935 , and the large ethnic group living in brazil has prevented crossbreeding . as a result , japanese physical characteristics can be easily noted in japanese descendants residing in brazil .
oriental eyelids have distinctive folds and contours that differentiate them from occidental eyelids due to inner anatomical relationships . the oriental eyelid shows a narrower tarsal plate , a higher level of subcutaneous fat , and a higher level of fat posterior to the orbital septum than is found in caucasian examples .
the eyelid crease , when present , is located near the upper eyelid border due to the following anatomical features : the orbital septum fuses to the eyelid levator muscle aponeurosis at variable distances below superior tarsal border ; the preaponeurotic fat protrusion and its thick feature blocks the attachments of the aponeurosis to orbicular muscle and skin next to the superior tarsal border ; and the levator aponeurosis attaches to the orbicular muscle and skin next to the upper eyelid border ( doxanas and anderson 1984 ; jeong et al 1999 ) .
in addition to this , there has been no comparison made between the eyelids measurement of native japanese and nikkeis living in other countries .
there is no information available as to whether habits , climate condition , or the exposure to different environmental factors could induce variation in the eyelid and its contours .
this study was constructed in order to analyze , in a quantitative form , the measurements of eyelid contours in japanese people living in japan and in nikkeis living in brazil by using digital images .
a prospective observational study was performed between august 2004 and july 2005 , evaluating 107 japanese descendents living in brazil ( so paulo state ) , and 114 japanese living in japan ( hamamatsu ) .
the studied populations were required to have resided in their respective countries since birth or for more than 60 years .
the protocol was approved by the ethics committee for human research at botucatu school of medicine ( unesp ) .
exclusion criteria included those with systemic diseases that could cause changes in palpebral position , those with ocular or eyelid diseases , those who had undergone palpebral surgery , those who would not authorize photographic records , and crossbreeding individuals .
all images were taken by the same person using a digital camera ( nikon coolpix 4100 , china ) , with flash , positioned in the frontal plane parallel to and 30 cm from the facial plane , at pupil height with a metric scale stick on the face and looking at the camera lens .
images were transferred to a computer running windows ( microsoft , redmond , wa ) and processed by scion image from the scion corporation ( frederick , md ) .
the following dimensions were analyzed : distance between medial canthi , distance between pupils ( ipd ) , superior palpebral crease position ( at the central part of the superior eyelid ) , the distance between superior palpebral margin and corneal reflex ( mrd ) , horizontal width , height , area , and obliquity of the palpebral fissure ( figure 1 ) .
data were analyzed by analysis of variance using a three factor model and respective multiple comparison tests .
the distance between medial canthi tended to be larger in the japanese than in nikkeis , with men having significantly greater values than women in both groups .
the ipd tended to be larger in the japanese , with men having larger ipd than women , and statistical difference for some age groups ( table 2 ) .
horizontal fissure values were barely higher in the japanese , with statistical significance for japanese women from 20 to 29 years , and japanese men from 40 to 49 years . comparing individuals within age groups , japanese women over 50 years had much lower values than the rest ( table 3 ) .
the smallest vertical fissure dimensions were found in the over 50 s ( table 4 ) .
mrd dimensions were similar in both populations , but there was a tendency for higher values in japanese ; the only significant difference was in female nikkeis who had larger dimensions than their japanese counterparts .
upper eyelid crease dimensions showed no statistical significance between group ; however , japanese women always had discretely higher values ( table 6 ) .
measurements in the individuals over 50 years old were significantly smaller ( table 7 ) .
comparison between age groups showed lower values as long as age advanced ( table 8) .
the shape and characteristics of the palpebral fissure are influenced by race , as has been documented in several racial comparative studies ( iosub et al 1985 ; leung et al 1990 ; kaimbo and kaimbo 1995 ; jeong et al 1999 ; hanada et al 2001 ) . in the present study we evaluated members of the oriental race living in different localities , and who were therefore submitted to distinct exogenous factors .
both populations consisted of similar numbers from both sexes and were divided into age groups to check for gender and age related differences ( lam et al 1995 ; siqueira et al 2005 ) .
differences between the nikkeis and japanese were very subtle , and frequently without significantly statistical difference .
distances between inner canthi and pupils tended to be higher in the japanese , and in men rather than women . for horizontal and vertical fissure ,
a reduction in palpebral fissure width was found mainly in women ( in the group older than 50 years old ) ; this has already been explored in literature ( van den bosch et al 1999 ; siqueira et al 2005 ) and can be attributed to disinsertion and slackness of the palpebral structures which occur at individuals of advanced ages ( nesi et al 1997 ) .
mean mrd values were higher in japanese than nikkeis in nearly all age groups , but differences were not statistically significant .
as a consequence of lower vertical fissure values , mean mrd values were also lower in more elderly individuals . in relation to crease height , differences were small and variability high ; this meant that it was necessary to use medians and inter - quartile amplitude with this parameter .
it is known that the oriental eyelid has a much lower superior palpebral crease position than a caucasian one , and it can even be absent due to particular anatomical differences .
it should be noted that the japanese often use adhesive to artificially shape the upper eyelid crease , which can often remain even after discontinuing the treatment , and could explain their discreet larger values .
discreet higher values in fissure width and height and mrd seen in japanese lead to their higher palpebral fissure areas .
the oldest population had lower values for this parameter , which certainly link it with senility , when smaller vertical and horizontal palpebral fissures cause smaller palpebral fissure area . however ,
when analyzed apart this did not have the same tendencies as mrd or vertical and horizontal fissures .
the palpebral fissure has a three - dimensional surface mainly shaped by the eyeball which pushes out and moulds both eyelid and all palpebral shape , including apexes and depressions , and the parabolic line of the superior lid , influencing the shape of the palpebral fissure ( maulboisson et al 2000 ) .
evaluation of fissure obliquity in caucasians , japanese and descendents , and brazilian indians shows mean inclinations of 4.60 , 9.39 , and 9.34 , respectively ( hanada et al 2001 ) . in this study , both groups had superior mean values ( 5.15 in nikkeis and 6.57 in japanese ) to the caucasian population , but less than orientals from a previous study ( hanada et al 2001 ) .
these results allow us to conclude that there are few differences in eyelids between orientals and the nikkeis who are living in brazil .
environmental factors were not sufficiently strong to change the genetic load which has determined the shape of the oriental lids until the present .
 objectivesquantitative evaluation of palpebral dimensions of japanese residents in japan and japanese descendant ( nikkeis ) who live in brazil , in order to define if environmental factors may influence these parameters.methodsa prospective study evaluating 107 nikkeis from brazil and 114 japanese residents in japan , aged 20 years or older . 
 exclusion criteria were those with palpebral position alterations , prior palpebral surgery , and crossbreeding . 
 images were obtained with a digital camera , 30 cm from the frontal plane at pupil height , with the individual in a primary position and the eye trained on the camera lens . 
 images were transferred to computer and processed by the scion image program . 
 measurements were made of distance between medial canthi , distance between pupils ( ipd ) , superior eyelid crease position , distance between the superior lid margin and corneal reflexes ( mrd ) , horizontal width , height , area , and obliquity of the palpebral fissure . 
 data were analyzed using analysis of variance for a three factor model and respective multiple comparison tests.resultsjapanese residents and nikkeis living in brazil have similar measurements . 
 statistical differences were found for some age groups concerning distance between pupils , horizontal , and vertical fissures , palpebral fissure area , and obliquity with native japanese presenting discretely higher measurements than nikkeis.conclusionenvironmental factors do not affect palpebral dimensions of nikkeis living in brazil . 
Introduction
Materials and methods
Results
Discussion
Conclusion