1. Presenter: Che-Hao Chuang Professor: Dr. Yen-Ting Chen
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

2. Outline Introduction Materials and Methods Results Discussions
Problems and Rationale
Purpose
Materials and Methods
Results
Discussions
Conclusions
Future works
Reference

3. Introduction
Problems and Rationale

4. 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

5. Problems and Rationale (2/7)
An orbital fracture due to trauma can induce complications:
Enophthalmos
Ocular motility limitation
Diplopia
Orbital emphysema
Injury to the inferior orbital nerve
Vision 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

6. Problems and Rationale (3/7)
Recognized sequelae of orbital blow-out fracture include:
Diplopia
Enophthalmos
sequelae: 後遺症

7. Problems and Rationale (4/7)
Diplopia (Double vision)
Pathology
Two images of a single object
Displace
Horizontally
Vertically
Diagonally
Monocular diplopia
Binocular diplopia
Horizontally:水平地(內外直肌) Vertically:垂直地(上下直肌) Diagonally:對角地(上下斜肌)
複視產生的原理是一隻眼睛的影像落在黃斑部的小凹，而另一眼的影像卻不落在小凹上， 落在小凹上的影像永遠比不落在小凹上的影像清晰，於是形成兩個影像。 
Diagram of Diplopia
From:
Monocular diplopia: 單眼複視 Binocular diplopia: 雙眼複視

8. Problems and Rationale (5/7)
Enophthalmos
Pathology:
The displacement backward of eyeball
The difference of eyes retraction is more than 2mm (3 to 4mm or more).
Congenital: Primary enophthalmos
Facial asymmetry & Dysplasia
Postnatal: Secondary enophthalmos
Origin: caused by the reduction of orbital contents or increase of volume of orbit cavity
primary enophthalmos:原發型眼球內陷 secondary enophthalmos:繼發型眼球內陷
From:

9. Problems and Rationale (6/7)
Medial wall
The most common fracture sites:
Orbital floor
Medial wall
An assessment of the fracture in the orbit and the ethmoidal sinus: CT
Clinical findings
Orbital floor

10. 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 tissue
Fat necrosis
Posterior soft-tissue fibrosis
Entrapped tissue：眼球後方的包埋組織 Fat necrosis：脂肪壞死會減少軟組織體積
Posterior soft-tissue fibrosis：後方軟組織纖維化

11. Introduction
Purpose

12. Purpose (1/2) Enophthalmos > 2.0 mm  Surgical intervention
During the acute posttrauma period
It is difficult to predict the degree of enophthalmos accurately.
It may be underestimated.
Orbital edema
如果因為沒辦法準確的預測眼球內陷的量而延遲動手術的時機，不僅程序上變得很困難，而且對手術結果也可能產生不利的影響。
在急性受傷期間，可能因為需要做一些外傷處理，如止血之類的，又因為可能有眼窩水腫現象，所以要預測眼球內陷的程度是很困難的。

13. Purpose (2/2) Using computer-based measurement
Enophthalmos
Volume of an orbital wall fracture
It may be beneficial in predicting indications for surgery.

14. Materials and Methods

15. 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 fracture
Lateral wall and roof fracture
Inadequate CT
Age less than 18 years
Surgical repair of the fracture
Lateral wall: 外側壁

16. Materials and Methods (2/6)
Medial wall
Inferior wall
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 system
Rapidia: CT or MRI  3D image

17. Materials and Methods (3/6)
Vol = A x 3 mm
Unit:
3 mm:
Section thickness
Measurement of the fracture area and volume (A–F)

18. Materials and Methods (4/6)
Statistical analysis
Pearson correlation coefficient (r)
Consecutive correlation between two variables
-1 ≦ r ≦ 1,
r > 0, positive correlation
r < 0, negative correlation
r = 0, no correlation
Fracture volume and late enophthalmos
Linear regression analysis
The relationship between Two consecutive variables
The prediction of late enophthalmos
Statistical software
SPSS

19. Materials and Methods (5/6)
Experimental cycle of Ophthalmic examination:
First day
One week
One month
Three months later

20. Materials and Methods (6/6)
Examination:
Visual acuity
Slit lamp examination
Pupillary reflex test
Goldmann diplopia test by perimetery
Extraocular motility measurement
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

21. Results

22. Results (1/7) The patient's gender classification
Men: 28 of 35 patients
Women: 7 of 35 patients
The patient‘s age classification
Mean age: years
Less than 50 years: 31 of 35 patients

23. Age and gender distribution
Results (2/7)
從表可以知道患者中青壯年人數占大部分，中年到老年人口的比例較少。
Age and gender distribution

24. Fracture volume and enophthalmos
Results (3/7)
(ml)
54.3%
Fracture volume and enophthalmos

25. Results (4/7)

26. 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.

27. Results (6/7) Volume of the orbital fracture Depth of enophthalmos
Less than 1 ml  0.91 mm
2 ml  1.74 mm
Depth of enophthalmos
2 mm  2.30 ml
0.84 mm for every 1.0 ml increase in volume

28. Amount of late enophthalmos predicted from the fracture volume
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.

29. Discussions

30. 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.

31. Discussions (2/5) Interrelated studies
To 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.

32. Discussions (3/5) Attentive item
Compared 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%.

33. Discussions (4/5) In the present study
Measuring the volume of the orbital fracture site.
Source: the consecutive coronal CT
Rapidia software
2D  3D
Area and volume

34. Discussions (5/5) Predicted benefits Decrease 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.

35. Conclusions

36. Conclusions (1/1) A significant correlation
The fracture site volume and the degree of late enophthalmos.
Predicting overall enophthalmos and provide useful information to surgeons.

37. Future works

38. Future works (1/1) Proof of orbital symmetry
Find out the relevant parameters
Increase the number of sample
Statistical verification

39. Reference

40. 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:
From:

41. Thank you for your attention