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Block 8 > Optics: Ant Seg. OCT > Flashcards

Optics: Ant Seg. OCT Flashcards

1
Q

OCT is a non-contact imaging technique which generates ___________ images of tissue

A

Cross-sectional

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2
Q

Coherent light has waves of light that are __________

A

In phase

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3
Q

Incoherent light has waves of light that are __________

A

Out of phase

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4
Q

Constrictive interference occurs when ____________

A

Waves combine

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5
Q

Destructive interference occurs when ___________

A

Waves cancel each other out

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6
Q

Interferometry is a method that uses ________________ to extract information

A

Interference of waves

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7
Q

Low-coherence light ensures that what contributes to the interference signal?

A

Only light from a narrow depth range

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8
Q

How does low-coherence light imaging impact retinal imaging?

A

Allows accurate layer-by-layer imaging

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9
Q

Why do we not need high coherence length for imaging the retina?

A

Because the retina is thin and layers are very close to each other

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10
Q

How does low-coherence light in OCT imaging impact axial resolution?

A

Increases axial resolution

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11
Q

OCT uses light in the near-infrared, which travels ________ than ultrasound

A

Much Faster

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12
Q

With Time-Domain OCT: light from the source is split into _________ and _______

A

Reference beam and central beam

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13
Q

OCT works by measuring the _________ and __________ reflected from different depths within the sample

A

Time delay and intensity of light

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14
Q

By using a reference arm, interference occurs only when the optical path difference between the sample and reference arms is within the ____________________

A

Coherence length of the light source

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15
Q

Anterior segment OCT: wavelength

A

1310 nm

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16
Q

Anterior segment OCT systems show __________ absorption and __________ penetration

A

Less absorption and deeper penetration

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17
Q

Retinal OCT: wavelength

A

830 nm

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18
Q

Retinal OCT systems have better ________ resolution

A

Axial

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19
Q

What was the first generation OCT?

A

Time-Domain OCT

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20
Q

What was the 2nd generation OCT?

A

Spectral Domain

21
Q

What was the 3rd generation OCT?

A

Swept-Source OCT

22
Q

Time-domain OCT relied on a moving _________ to do what?

A

Relied on a moving mirror to scan each depth position, pixel by pixel

23
Q

Did the time-domain OCT have to be physically moved?

A

Yes to scan various depth or layers

24
Q

Fourier Domain OCT has a _________ reference arm

25
Q

Fourier Domain OCT Light Source:

A

Broadband light source (840-850 nm)

26
Q

Broadband light source in Fourier domain OCT produces a ____________________

A

Spectrum of backscattered light

27
Q

Backscattered light in Fourier Domain OCT is measured by a _____________

A

Spectrometer

28
Q

With Fourier Domain OCT, the frequency components of backscattered light can be analyzed either ____________ or ____________

A

Spatially (Spectral Domain OCT)

Temporally (Swept Source OCT)

29
Q

5 Advantages of Fourier Domain OCT

A
  1. High speed
  2. High resolution
  3. Layer-by-layer assessment
  4. Larger scanning areas
  5. 3D scanning
30
Q

Scanning speed of Time Domain vs. Fourier Domain

A

Time Domain: 400 A-scans/sec
Fourier Domain: 26,000 A-scans/sec

31
Q

Depth Resolution of Time Domain vs. Fourier Domain

A

Time Domain: 10-15 microns
Fourier Domain: 5 microns

32
Q

B-Scan time of Time Domain vs. Fourier Domain

A

Time Domain: 1.3 secs
Fourier Domain: 0.04 secs

33
Q

Reference mirror of Time Domain vs. Fourier Domain

A

Time Domain: Moving
Fourier Domain: Stationary

34
Q

Motion Handling of Time Domain vs. Fourier Domain

A

Time Domain: Slower than eye movement
Fourier Domain: Faster than eye movement

35
Q

Image quality of Time Domain vs. Fourier Domain

A

Time Domain: Lower
Fourier Domain: Higher

36
Q

What is the advantage of Spectral Domain OCT having such a fast scanning speed?

A

Helps to minimize motion and possible artifacts

37
Q

Comparison of Anterior segment OCT and Retinal OCT wavelength of light source

A

Anterior segment uses a higher wavelength light source (1310 nm) compared to Retinal OCT (840 nm)

38
Q

Anterior Segment OCT: What is a Line scan?

A

A cross-sectional view of the cornea or anterior chamber angle

39
Q

Anterior Segment OCT: What is a Raster scan?

A

Series of parallel line scans. Allows for more comprehensive assessment of corneal thickness and pathology

40
Q

Anterior Segment OCT: What is a Radial scan?

A

Multiple scans radiating from the center of the cornea or angle to assess symmetry and depth

41
Q

Anterior Segment OCT: What is a Pachymetry Map?

A

A thickness map of the cornea used to evaluate corneal thinning or edema

42
Q

What type of OCT imaging is important when diagnosing conditions like corneal dystrophies, keratoconus, narrow-angle glaucoma, and post-surgical complications?

A

Anterior segment OCT

43
Q

What type of OCT imaging is important when diagnosing conditions like age-related macular degeneration (AMD), diabetic macular edema, retinal detachments, and epiretinal membranes?

A

Posterior segment OCT

44
Q

What type of OCT imaging would help assess swelling of the cornea?

A

Anterior segment OCT

45
Q

What type of OCT imaging would help assess corneal ulcers?

A

Anterior segment OCT

46
Q

What type of OCT imaging would help assess Pterygium?

A

Anterior segment OCT

47
Q

What type of OCT imaging would help assess open and closed angle evaluations?

A

Anterior segment OCT

48
Q

What type of OCT imaging would help assess anterior chamber depth?

A

Anterior segment OCT

49
Q

Does OCT provide a pachymetry map? What does a Pachymetry map show us?

A

Yes, pachymetry map shows us corneal thickness across the entire cornea.

Block 8 (30 decks)

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