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Prediction of Enophthalmos by Computer-Based Volume Measurement of Orbital
Fractures in a Korean Population
Ahn HB, et. al. Ophthalmic Plastic and Reconstructive Surgery. 2008 ;24 : 36–9.
Presenter: Che-Hao Chuang
Professor: Dr. Yen-Ting Chen
Date: 2009/12/08
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Outline
IntroductionProblems and RationalePurpose
Materials and MethodsResultsDiscussionsConclusionsFuture worksReference
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Problems and Rationale (1/7)
Orbital blow-out fractures are frequent due to popularity of motorcycle traffic accident.
Orbital blow-out fracture: 眼窩骨折
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Problems and Rationale (2/7)
An orbital fracture due to trauma can induce complications:
EnophthalmosOcular motility limitationDiplopiaOrbital emphysemaInjury to the inferior orbital nerveVision loss
Enophthalmos: 眼球內陷 Ocular motility limitation: 眼睛的能動性限制 Diplopia: 複視 Orbital emphysema: 眼窩氣腫
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Problems and Rationale (3/7)
Recognized sequelae of orbital blow-out fracture include:
Diplopia Enophthalmos
sequelae: 後遺症
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Problems and Rationale (4/7)
Pathology Two images of a single
object
Displace Horizontally Vertically Diagonally
1. Monocular diplopia
2. Binocular diplopiaDiagram of Diplopia
Monocular diplopia: 單眼複視 Binocular diplopia: 雙眼複視
Diplopia (Double vision)
From:http://www.clinico.com.tw/eye1/eye12/eye126/I126l.htm
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Problems and Rationale (5/7)
EnophthalmosPathology:
The displacement backward of eyeball The difference of eyes retraction is more than
2mm (3 to 4mm or more).Congenital: Primary enophthalmos
Facial asymmetry & DysplasiaPostnatal: Secondary enophthalmos
Origin: caused by the reduction of orbital contents or increase of volume of orbit cavity
From: http://blog.udn.com/jnwu/2937626
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Problems and Rationale (6/7)
The most common fracture sites:Orbital floorMedial wall
An assessment of the fracture in the orbit and the ethmoidal sinus:CTClinical findings
Medial wall
Orbital floor
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Problems and Rationale (7/7)
The underlying cause of enophthalmos:A discrepancy between the volume of the orbital
soft tissue and the bony orbital cavity
Displacement of the orbital tissue from the bony orbit:Entrapped tissueFat necrosisPosterior soft-tissue fibrosis
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Purpose (1/2)
Enophthalmos > 2.0 mm
Surgical intervention
During the acute posttrauma periodIt is difficult to predict the degree of enophthalmos
accurately.It may be underestimated.
Orbital edema
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Purpose (2/2)
Using computer-based measurement EnophthalmosVolume of an orbital wall fracture
It may be beneficial in predicting indications for surgery.
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Materials and Methods (1/6)
Sample of research: Thirty-five Korean patients with orbital blowout
fractures who were not treated with surgery.
Exclude criteria:Bilateral orbital wall fractureLateral wall and roof fractureInadequate CTAge less than 18 yearsSurgical repair of the fracture
Lateral wall: 外側壁
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Materials and Methods (2/6)
In 35 patients 25 patients
A fracture in the medial wall of the orbit 2 patients
A fracture in the inferior wall 8 patients
A combined fracture in the medial wall and inferior wall
CT scanning system: SOMATOM Sensation 16
Image processing systemRapidia: CT or MRI 3D image
Medial wall
Inferior wall
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Materials and Methods (3/6)
3mm
Measurement of the fracture area and volume (A–F)
Vol = A x 3 mmUnit:
3 mm: Section thickness
3mm
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Materials and Methods (4/6)
Pearson correlation coefficient (r)Consecutive correlation
between two variables-1 ≦ r ≦ 1, r > 0, positive correlation
r < 0, negative correlation
r = 0, no correlationFracture volume and late
enophthalmos
Linear regression analysisThe relationship between
Two consecutive variables
The prediction of late enophthalmos
Statistical softwareSPSS
Statistical analysis
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Materials and Methods (5/6)
Experimental cycle of Ophthalmic examination: First day One week One month Three months later
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Materials and Methods (6/6)
Examination:1. Visual acuity
2. Slit lamp examination
3. Pupillary reflex test
4. Goldmann diplopia test by perimetery
5. Extraocular motility measurement
6. Hertel ophthalmometry to measure enophthalmos
Slit lamp: 裂隙燈 Extraocular motility: 眼外能動性
Pupillary reflex: 瞳孔反射 Hertel ophthalmometry: 赫特爾突眼計
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Results (1/7)
The patient's gender classification Men: 28 of 35 patientsWomen: 7 of 35 patients
The patient‘s age classificationMean age: 37.06 yearsLess than 50 years: 31 of 35 patients
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Results (5/7)
Mathematical formula of linear regression analysis:
E = enophthalmos (mm)
V = fractured site volume (ml)
SEE = standard error of estimate
It was used to calculate the expected degree of late enophthalmos.
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Results (6/7)
Volume of the orbital fractureLess than 1 ml 0.91 mm2 ml 1.74 mm
Depth of enophthalmos2 mm 2.30 ml0.84 mm for every 1.0 ml increase in volume
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Results (7/7)
Amount of late enophthalmos predicted from the fracture volume
Enophthalmos of 2 mm or more was predicted with an orbital fracture volume of 2.30 ml.
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Discussions (1/5)
Why use CT?Many studies have mentioned
E.X. Gilbard et al.
Best means of observing the bone structure and soft tissues of the orbit.
It’s great help in predicting the prognosis of a patient with a fracture in the orbital floor.
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Discussions (2/5)
Interrelated studiesTo predict enophthalmos after an orbital fracture,
per ml increase in the orbital volume.Raskin et al. 0.47 mm (per ml)Whitehouse et al. 0.77 mm (per ml)Ploder et al. 0.81 mm (per ml)Fan et al. 0.89 mm (per ml)
However, less studies that focused on orbital fracture patients without surgical treatment.
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Discussions (3/5)
Attentive itemCompared with the orbital volume of the normal eye
A tilted head positioning during CT scanning
Normally, the volume between the right and left orbit may differ by approximately 7% to 8%.
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Discussions (4/5)
In the present studyMeasuring the volume of the orbital fracture
site.Source: the consecutive coronal CTRapidia software
2D 3DArea and volume
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Discussions (5/5)
Predicted benefitsDecrease mistake
Surgical repair is not always necessary in the treatment of orbital fractures.
Underestimation of the amount of late enophthalmos
It won’t delay with surgery.
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Conclusions (1/1)
A significant correlationThe fracture site volume and the degree of late
enophthalmos.
Predicting overall enophthalmos and provide useful information to surgeons.
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Future works (1/1)
Proof of orbital symmetryFind out the relevant parametersIncrease the number of sampleStatistical verification
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Reference (1/1)
Ahn HB, et. al. Prediction of Enophthalmos by Computer-Based Volume Measurement of Orbital Fractures in a Korean Population. Ophthalmic Plastic and Reconstructive Surgery. 2008 ; 24 : 36–9.
From:http://www.clinico.com.tw/eye1/eye12/eye126/I126l.htm
From:http://blog.udn.com/jnwu/2937626