coordinator 蔡明霖副教授

1. OCT原理及在眼科的應用
科林儀器股份有限公司
金守仁

2. 內容
• Tomography 斷層掃描儀
• OCT原理
• OCT發展歷史
• OCT在眼科的應用

3. Tomography 斷層掃描儀

4. OCT
• Optical Coherence Tomography
• Tomography的概念

5. 現有Tomography的技術

6. 現有Tomography的技術

7. 現有Tomography的技術
• 限制:X-ray CT, MRI, PET為目前醫療診斷主力且發
展相當成熟,但受限於解析度只達mm等級,因此希
望能有更細微的影像技術來做檢測
• 更高解析度的技術產生
• Fluorescence microscopy
• Confocal Microscope
• Ultrasound
• OCT

8. 現有Tomography的技術
• Fluorescence microscopy
• 1. 以短波長光源激發螢光物質而發出較長波長的螢光
• 2. 螢光光譜的變化可以檢測組織的變異
• 3. 橫向解析度可達0.5 mm
• Confocal microscopy
• 1. 共焦掃描顯微的原理在1957年由Marvin Minsky所提出,並於
1969年由 P. Davidovits與M. D. Egger利用雷射而發展出第一
套共焦掃描顯微鏡
• 2. 具有空間光學切片的能力
• 3. 橫向與縱向解析度分別可達0.5與 1um
• 4. 可與螢光顯微術搭配
• 5. 與超快雷射搭配做非線性光學的檢測

9. 穿透力 v.s.解析度
超音波影像系統 共焦掃瞄顯微術 光學同調斷層掃瞄技
(Confocal) 術(OCT)
穿透力 最佳(10cm) 最弱(1mm) 中(2-8mm)
解析度 最差 最佳 中
(數十至數百個μm) (1 μm) (1-15um)

10. Biological measurement
Electron Microscopy
MRI Optical Microscopy
Ultrasound Confocal
X-ray CT SLD OCT Femtosecond laser
10 mm 1 mm 100 µm 10 µm 1 µm 0.1 µm
Retina Intra-retinal structure
Individual Cell
Nucleus

11. Tomography技術參數比較

12. OCT原理

13. OCT 定義
• Optical coherence tomography (OCT) is an
interferometric, non-invasive optical tomographic
imaging technique offering millimeter penetration
(approximately 2--3 mm in tissue) with sub-
micrometre axial and lateral resolution.
--From Wikipedia
• (Optical Coherence Tomography, OCT)是採用光
學造影的方法，主要是利用低同調波長與寬頻光
源之光學特性，結合反射式干涉技術之原理，來
解析待測組織之縱向結構，其影像解析度甚至可
達次微米等級

14. 同調光與低同調光
• 同調性光源：具有近似於單一波長、單一相位的窄頻光譜，
使光束中波前上每點的光相位相等，為同調
光
• 低同調性光源：具有一波長範圍的光譜，也就是由不同波
長的光所組合而成的寬頻光源

15. OCT 頻寬與波長的選擇
• 提高解析度的方式：
• 增加頻寬
• 在相同的頻寬下，波長較短的解析度較佳
• 波長的選擇上得配合待測物適用波長的範圍。
• 以醫療上的應用為例，人體組織適用的光波長範圍在約700nm
到1300nm米間，波長小於700nm的光易被蛋白質以及黑色素所
吸收，長於1300nm的則容易被水吸收。
• 因此若OCT 系統要應用於人體組織的量測時，就得選擇在這之
間的波段,稱為生物窗（Biological window）。
• 1300nm的光較不易被散射，可以收集到較深的光訊號，
觀察到較深的區域(前房OCT)。

16. Optical Source

17. Michelson Interferometer
• 組成
• A monochromatic source
• A detector
• Two mirrors
• One beam splitter
• 簡單,常見
• 用途
• astronomical interferometers
• gravitational wave detectors

18. Optical Coherence Tomography
Basic Principle
Reference Mirror
Beam Splitter
Light
Source
Detector
To computer & display
OCT Signal

19. TIME DOMAIN OCT
Reference Mirror
Superluminescent Beam splitter
Diode (SLD)
one signal return
To computer
and display Photodetector

20. Time Domain OCT Reference mirror
moves back and forth
Lens
Broadband
Light Source
Distance determines
SLD depth in A scan
Interferometer
Detector Combines light
from reference
with reflected
Creates light from retina
A-scan
Scanning mirror
1 pixel
directs SLD
at a time
beam on retina
Each A-
scan
has 400 Process
pixels Data Acquisition repeated many
times to create
Processing B-scan
Final A-scan

21. SPECTRAL DOMAIN OCT
Reference Mirror
Superluminescent Beam splitter
Diode (SLD)
Multiple signal return (up to 200)
To computer
and display Spectrometer & CCD

22. Fourier Domain OCT
Reference mirror
stationary
Broadband
Light Source
SLD
Interferometer
Combines light
from reference
Grating with reflected
splits signal light from retina
by
wavelength
Spectrometer
analyzes
signal by
wavelength FFT
Spectral Fourier transform Entire A-scan
interferogram converts signal to created at a
typical A-scan single time

23. OCT發展歷史

24. OCT的問世
• 西元1991 年由 James G. Fujimoto首先發表出
來
Professor James G. Fujimoto
Professor of Electrical Engineering
Massachusetts Institute of Technology
USA
Research:
1. Application of femtosecond laser technology
2. Studies of ultrafast phenomena
3. Laser medicine and surgery
4. Development of optical coherence tomography
 James G. Fujimoto, Science, 1991
 What is OCT: Diagnostic medical imaging techonology
 Why OCT: better diagnose and treat disease
 Main application areas: Retinal disease, heart disease and
cancer

25. 眼科OCT編年史- 華人之光
• 1991, David Huang的論文刊登於Science
• 1994, 第一個臨床原型機
(Jay Wei - Ziess OCT Tech. Leader)
• 1996, OCT1 生產 (100 A掃描/秒, 16um 解析
度)
黃大衛(David Huang)
• 1999, OCT2 生產 (OCT1 技術)
• 2001, OCT3 生產 (400 A掃描/秒, 10um 解析
度)
• 2004, FD-OCT技術 (>20,000 A掃描/秒)
• 2005, Visante前節OCT（30um分辨率）
• 2006, RTVue （第一個透過FDA的FD-OCT）
• 2007, RTVue前節傅立葉OCT(解析度5um）
& 全球常態數據庫完成
魏傑(Jay Wei)

26. At first, OCT was slow
• First OCT image taken by Huang and Schuman
over night in James Fujimoto’s laboratory, MIT
• Huang D et al. Science, 254:1178 (1991).

27. OptoVue
RTVue 2006
A generational leap
26,000
Fourier domain
Speed
(A-scans
/sec)
Time domain
400 Zeiss
OCT1/2
100 Zeiss Stratus
1996
2002
16 10 5
Resolution (µm)
• RTVue has 65x speed & 2x resolution of Stratus

28. Evolution of Commercial OCT

29. Time Domain OCT Fourier Domain OCT
• Sequential • Simultaneous
• 1 pixel at a time • Entire A-scan at once
• 400 pixels per A-scan • 2048 pixels per A scan
• 0.25 seconds per A scan • .00000385 sec per A scan
• 512 A-scans in 1.28 sec • 1024 A-scans in 0.04 sec
• Slower than eye movements • Faster than eye movements
Motion artifact Small blood vessels
IS/OS
Choroidal vessels
512 A-scans in 1.28 sec
1024 A-scans in 0.04 sec
Higher speed, higher definition and higher signal.

30. 診斷設備的設計原則
• 安全性
• 非侵入性
• 非接觸性
• 準確性及再現性
• 使用方便性

31. 現有眼科OCT設備

32. OCT在眼科的應用

33. 眼睛的構造

34. 眼底構造

35. 臨床應用
• 視網膜
• 青光眼
• 角膜
• 白內障

36. 視網膜常用掃描模式
• Cross line scan
• 0.156 seconds
• 2 x 1024(16 scans in
each direction are
then averaged)
• 結構的觀察

37. Retina

38. CME

39. 高度近視

40. ERM
Epiretinal membrane

41. DM
Diabetic Maculopathy

42. Macular Hole

43. Polypoidal Choroidal Vasculopathy

44. AMD Advanced

45. 視網膜常用掃描模式
• EMM5 scan
• 1.30 seconds
• 13 horizontal lines
with 6mm scan length
+ 8 horizontal lines
with 4mm scan length
• 13 vertical lines
with 6mm scan length
+ 8 vertical lines
with 4mm scan length
• 訊息量化

46. Analyze Manu
• EMM5
• 數據提供
• 與正常值比較

47. Analyze Manu
• EMM5

48. Analyze Manu
• EMM5-Progression Overview

49. 視網膜常用掃描模式
• 3D scan
• 2.4 seconds
• 141 B-scans equally
spaced to cover
7mm x 7mm volume
• 3D圖像觀察

50. Macular PVD

51. Auto scan

52. Auto play

53. RPE-Auto play

54. 青光眼常用掃描模式
• ONH scan
• 0.55 seconds
• 12 radial line scans 3.4mm
length & 13 concentric rings
(1.3 - 4.9mm diameter)
All centered on disc
• 視神經頭

55. LOCALIZED NERVE FIBER BUNDLE
DEFECTS

56. Glaucoma Samples
ppRNFL TSNIT
NFL Thickness Map
ONH Analysis Ganglion Cell Complex Analysis

57. Normal vs Glaucoma
Enlarged Cup
Cup
Rim
RNFL thinning
RNFL
Inner Retina
Macula Map Ganglion
cell loss in
macula
Normal Glaucoma

58. Optic Nerve Head / RNFL Trend Analysis
Optic Disc and RNFL Thickness
Maps in order first to last.
TU
TSNIT Deviation Maps
Each visit has separate color
and is plotted on the same
graph with normal range
shown. Color Legend is next
to graph.
RNFL parameter trend analysis
shows graphically changes in
RNFL parameters, Avg RNFL,
Sup Avg, and Inf Avg.
RNFL & Optic Disc parameter table
for all exams. Color coded
according to database comparison.
Final column gives change from 58
most recent visit to baseline.

59. 64/M, POAG (OS)

61. 青光眼常用掃描模式
• GCC scan
• 0.58 seconds
• 1 horizontal line with 7mm scan
length, followed by 15 vertical
lines with 7mm scan length and
0.5mm interval, centered 1mm
temporal to fovea
• 黃斑部周邊視神經纖維

62. Ganglion Cell Complex: Thickness / Deviation
from Normal / Significance of Deviation
• GCC Thickness
•Deviation from
Normal
•Significance of
Deviation

63. GCC Glaucoma
GCC Thickness Map –
Large area of superior t
thinning OS, inferior thinning
OD
Deviation Map shows 50%
GCC loss in affected areas
Regions with damage are
highly significant
Parameters are outside
normal limits
64

64. 3D
Comprehensive
Presentation
-Precise Disc
margin
verification
-Visit-to-visit
registration
-Sum of C-scans
-User defined
depth of C-scan
-Auto animation
presentation
(Lower right or
full screen)

65. 青光眼常用掃描模式
• 3D Disc scan
• 2.2 seconds 101 frames
equally spaced B-scans to
cover a square volume
• fixation at 20o nasal
• 視神經頭3D圖像觀察

66. 3D Optic Disc Auto-Animation

67. 3D Optic Disc Auto-Animation

68. 角膜常用掃描模式
• Pachymetry scan
• 0.32 seconds
• 8 x 6mm x 2.0mm
Radial Scans
• 角膜厚度

69. Pachymetry Maps

70. Cornea power

71. 角膜常用掃描模式
• Angle scan
• 0.04 seconds
• 1 x 3mm x 2.3mm
• 隅角結構觀察與測量

72. Angle measurement

73. OCT is useful in the measurement of
tear meniscus in dry eye

74. Analyze Manu
• 3D Auto Play
Demo

75. Q&A