blow - out fracture of the inferior orbital wall is defined as fracture of an outer wall that supports the lower part of an orbit by the impact of blunt trauma , producing increased internal pressure . the importance of the diagnosis to treatment of the blow - out fracture is rising because of industrialization , increasing transportation speed , and increased violent accidents . for the diagnosis of orbital trauma , computed tomography ( ct ) is the most accurate radiologic imaging technique . although a fracture of the orbital inferior wall was in the past often difficult to detect by two - dimensional radiography , ct allows these injuries to be diagnosed much more readily . the coronal plane of ct is especially useful for the inferior wall fracture . while ct is more accurate , there are no obvious guidelines to predict prognosis or to decide surgical repair . evaluating the location and amount of fracture with altered volume and extents of orbit provides objective indicator of a blow - out fracture . this study assessed the association between eye symptoms ( enophthalmos or diplopia ) and site of damage , volume , deviated inferior rectus muscle ( irm ) and type of fracture with ct . the intent is to anticipate the prognosis of orbital trauma at the early stage and provide indications to decide surgical repair . from january 2009 to april 2014 , 63 patients who came to pusan national university hospital with a chief complaint of orbital injury were diagnosed with orbital floor fracture . patients with fracture of both orbits were excluded because it was impossible to measure the relative value of fragment deviation . every patient underwent ct , and age , sex , cause of injury , location of fracture , and symptoms were documented in the medical record . of the patients who underwent surgery , the following were evaluated : operating method , material , change in symptom , diplopia , and the limit of eyeball movement . if the difference was more than 2 mm , it was judged that patient had enophthalmos . the boundary was sectioned into anterior border ( 50% of infraorbital rim using coronal plane image s boundary ) , posterior border ( optic canal ) , and medial border ( ethmoidomaxillary suture ) ( fig . the length of orbital floor ( l ) , length between medial anatomic landmark to fragment s internal border ( x ) and external border ( y ) , and each fragment of volume in the bone fragment s movement was measured . for each measured value , ct slice ( 3 mm ) was multiple to estimate the area of bone fragment as well as the absolute value of malposition volume . relative value was calculated by dividing non - damaged side of orbital floor length and volume of orbit . v=(snn1an)v0 
 e = snn1(yxl ) v = displaced tissue volume , s = slice ( 3 mm ) , n = total number of slices , v0=volume of opposite orbital side , e = area of fracture segment displacement of the irm increases the risk of eye symptoms . irm displacement was classified by the relative location of irm and an imaginary line between the medial and lateral boundary of the fracture site on the sagittal plane ( fig . if the line is located just above the orbital floor , irm displacement is classified as grade 1 , the line lying on the orbital floor but more than half located inside the orbit is grade 2 , more than half of the line outside of the orbit is classified as grade 3 , and completely outside of the orbit is grade 4 . there are two broad types of inferior orbital wall fracture : trap - door ( one side of bone fragment is attached to the orbital floor ) , and punched - out ( both sides of bone fragment are unattached ) ( fig . the authors assessed the association between symptom status ( enophthalmos or diplopia ) and site of damage , volume , deviated irm and type of fracture with ct using the non - parametric mann - whitney test or kendall s tau as appropriate . kendall s tau ( a type of rank correlation ) provides a distribution - free test of independence and a measure of the strength of association between two variables . null hypotheses of no association were rejected if p - values were less than 0.05 . data were analysed using the ibm spss statistics ver . 20.0 ( ibm co. , armonk , ny , usa ) . of 45 patients , 39 ( 86.7% ) were male and 6 ( 13.3% ) were female . the patients were sorted into two groups based on symptom status ( enophthalmos or diplopia ) . the symptom - free group ( group a ) included 27 patients , of whom five underwent surgery . although these five patients had no symptoms , they underwent surgical reconstruction of the orbital floor because their displacement was large enough to predict delayed symptom occurrence . this group consisted of 18 people : 12 with diplopia , one with enophthalmos , and five with both . the association of the primary outcome , symptoms of diplopia or enophthalmos , was tested with three predictor variables : the extent of the damaged area by volume , the amount of irm deviation , and type of fracture . by ct measurement , the average fracture area was 242.0 mm ( 12.4737.0 mm ) and average herniated volume of inferior wall was 10,88.2 mm ( 13.24,172.2 mm ) ( table 2 ) . the group a mean area was 192.6 mm ( 12.4426.0 mm ) and mean volume was 673.2 mm ( 13.22,343.0 mm ) . the group b area was 316.2 mm ( 95.7737.0 mm ) and volume was 1,710.6 mm ( 275.44,172.2 mm ) . symptom status was associated with both affected area and herniated volume ( p < 0.05 ) . the comparative effect of volume and area on symptom status was analyzed by kendall s tau test . the association of volume with symptom status by kendall s tau was 0.07 , smaller than the association of area with symptom status , 0.28 . our interpretation is that volume is more influential in symptom status . whether symptom status included both diplopia and enophthalmos or just one symptom did not affect the associations with area and volume . irm displacement was categorized into four grades by the location of rectus muscle . in group a , 12 patients were grade 1 , 11 were grade 2 , four were grade 3 , and none were grade 4 . of group b patients , three were grade 1 , two were grade 2 , six were grade 3 , and six were grade 4 ( table 3 ) . symptom status and higher grade were associated based on the correlation analysis in groups ( p < 0.05 ) . although correlation between the displacement of irm and the area of fracture site was low , the connection with displaced volume is statistically significant . also , both diplopia and enophthalmos occurred when irm displacement degree was high . there were 26 patients with trap - door fracture ( one side - attached to the fracture ) and 19 with punched - out ( both sides detached ) . in group a , there were 19 trap - door type and eight punched - out type . in group the punched - out type is more strongly associated with symptom status and is statistically significantly associated with increase of area and volume ( p < 0.05 ) ( table 4 ) . by ct measurement , the average fracture area was 242.0 mm ( 12.4737.0 mm ) and average herniated volume of inferior wall was 10,88.2 mm ( 13.24,172.2 mm ) ( table 2 ) . the group a mean area was 192.6 mm ( 12.4426.0 mm ) and mean volume was 673.2 mm ( 13.22,343.0 mm ) . the group b area was 316.2 mm ( 95.7737.0 mm ) and volume was 1,710.6 mm ( 275.44,172.2 mm ) . symptom status was associated with both affected area and herniated volume ( p < 0.05 ) . the comparative effect of volume and area on symptom status was analyzed by kendall s tau test . the association of volume with symptom status by kendall s tau was 0.07 , smaller than the association of area with symptom status , 0.28 . our interpretation is that volume is more influential in symptom status . whether symptom status included both diplopia and enophthalmos or just one symptom did not affect the associations with area and volume . irm displacement was categorized into four grades by the location of rectus muscle . in group a , 12 patients were grade 1 , 11 were grade 2 , four were grade 3 , and none were grade 4 . of group b patients , three were grade 1 , two were grade 2 , six were grade 3 , and six were grade 4 ( table 3 ) . symptom status and higher grade were associated based on the correlation analysis in groups ( p < 0.05 ) . although correlation between the displacement of irm and the area of fracture site was low , the connection with displaced volume is statistically significant . also , both diplopia and enophthalmos occurred when irm displacement degree was high . there were 26 patients with trap - door fracture ( one side - attached to the fracture ) and 19 with punched - out ( both sides detached ) . in group a , there were 19 trap - door type and eight punched - out type . in group the punched - out type is more strongly associated with symptom status and is statistically significantly associated with increase of area and volume ( p < 0.05 ) ( table 4 ) . surgical reconstruction of orbit wall must be considered when traumatic diplopia and enophthalmos occur . however , because symptoms can occur not just immediately after the injury but after two or three weeks have passed , deciding whether to treat surgically is difficult . therefore , it is important to predict whether the orbit wall fracture will cause delayed eye symptoms like diplopia or enophthalmos . commonly used surgical indications for reconstructing the orbit wall are clinical diplopia , herniation of orbital tissue on ct image , enophthalmos more than 2 mm , and large fracture that passes over half of orbital bone[11 - 14 ] . in this study , criteria predictive of symptom status were examined using the most generalized medium for diagnosis , ct . manson et al . insisted that the degree of enophthalmos is directly proportional to the herniated volume of orbital tissue caused by a blow - out fracture that widens the fracture area . measuring the altered area and volume of orbital floor fracture using ct will be helpful to predict the degree of enophthalmos and to decide the feasibility of surgery . ploder et al . found area and volume of deviated orbital tissue by measuring the width and height of fracture on coronal plane . jin et al . assumed that the deviated fragment is an oval , and calculated the area and volume of tissue fallen off by measuring width , length and height . the volume of the injured orbit can nowadays be compared with the non - affected side using three - dimensional images . in this case , the error can occur up to 7% to 8% in volume difference of both orbits and error can be made by each observer who establishes the orbit area . in this study , area and volume of fragment were calculated by adding up the length and width of bone fragments in each coronal ct image . by using this method , relative accuracy can be secured by measurement reproducibility in definite anatomical structure . in this study , the association of eye symptoms with types of fracture , location of irm , and area and volume of bone fragment measured using ct was evaluated . the findings were interpreted to mean that as deviated bone fragment area and volume of herniated tissue increase , the more symptoms occur . also , of volume and area , therefore , malposition of irm by more than half of the orbital floor significantly affects the presence of symptoms . three of 13 ( 23.1% ) patients who had one symptom were grade 4 while three of five ( 60% ) patients who had both eye symptoms were grade 4 ( irm with complete orbital floor herniation ) . insisted that surgery be considered when the grade was more than 2 , and occurrence of symptoms was more frequent in grade 3 and 4 . according to thaller - antlanger s research , type of fracture had a significant effect on prognosis , with punched - out fracture followed by orbital rim fracture predicting a poor prognosis . we found that punched - out type were less common ( 42% ) , and more related to occurrence of symptoms than trap - door type . in addition , four out of five patients who had enophthalmos and diplopia had punched - out fractures . a 57-year - old female patient presented with a punched - out type fracture by ct resulting from a pedestrian traffic accident . her symptoms were not serious , with no transition of bone fragment , and no enophthalmos and/or diplopia . after two weeks , she had delayed surgery because enophthalmos of 2 mm and slight diplopia developed . presumably , two bone fragments could not support the orbit structure due to gravity and the symptoms developed . such an unusual case helps support the hypothesis that punched - out type fractures have a stronger association with symptom occurrence . the sample size was small , and , especially , grade 3 and 4 of serious irm deviation were few . measurement reproducibility on ct , measuring area and volume of deviated bone fragment was difficult . to conclude from our results , area , volume , location of irm , and type of fracture measurement of fracture area and volume , evaluation of the deviated irm and classification of the fracture type by coronal ct are effective for predicting the prognosis and surgical indication . among these , the volume of deviated tissue is more strongly related to symptoms than the area of bone fragment . when the irm is more than half out of orbital floor , punched - out fractures have a higher risk of symptom occurrence and surgical treatment should be considered to reconstruct the structure . this study investigated and targeted 45 patients with orbital blow - out fracture visiting the department of oral and maxillofacial surgery of the dental clinic center in pusan national university hospital located at busan , including both outpatient and emergency room visits from january 2009 to april 2014 . the purpose of this study is to review the association between the occurrence of enophthalmos or diplopia , and damaged area , volume , deviated irm and type of fracture by using the ct , to anticipate the prognosis of orbital trauma on the early stage , and to provide an indicator for the decision of surgical reconstruction of the orbital floor . the results of the investigation are shown below . 
 the more deviated bone fragment area and volume of herniated tissue increase , the stronger the risk of symptom occurrence . also , between volume and area , volume is more related.deviation of irm more than half of orbital floor ( grade 3 and 4 ) affects significantly the occurrence of symptoms.while punched - out fractures are less common , they are more associated with occurrence of symptoms than trap - door type and are more important in the increase of volume and area . the more deviated bone fragment area and volume of herniated tissue increase , the stronger the risk of symptom occurrence . also , between volume and area , volume is more related . deviation of irm more than half of orbital floor ( grade 3 and 4 ) affects significantly the occurrence of symptoms . while punched - out fractures are less common , they are more associated with occurrence of symptoms than trap - door type and are more important in the increase of volume and area . injured orbital area , herniated volume , deviation of irm and type of fracture are all related to eye symptoms . in orbital trauma , measurement of fracture area and volume , evaluation of the deviated irm and classification of the fracture type by coronal ct are effective for the management of orbital trauma and predicting the prognosis .