Anterior Segment Optical Coherence Tomography Flashcards

1
Q

What was the first cornea image taken with

A

OCT

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2
Q

OCT principal of operation

A

Picks up scatter

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3
Q

Why do we use low coherence for OCT

A

Within a short time/length difference you get strong signal

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4
Q

Why does wavelength matter in OCT

A

Deeper penetration and better axial resolution

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5
Q

What is the drive for selecting wavelength

A

Water

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6
Q

What dictates the use of different wavelengths

A

Water absorption minimization

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7
Q

Penetration length depends on

A
  • source center wavelength
  • tissue density
  • source power-acquisition rate
  • water absorption minimization
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8
Q

What is resolution dependent primarily on in infrared

A

Source spectral profile

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9
Q

What’s the difference between time domain and Fourier domain

A

Time domain is much slower

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10
Q

What is the best OCT

A

Fourier domain

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11
Q

What is the clinical application of being able to use high resolution in OCT

A

Can see intracrania and intralenticular details

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12
Q

What’s the difference between confocal and OCT

A

Confocal is way too slow and is primarily used to view cells

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13
Q

How is pachymetry scanned

A

Take a number of scans really fast. Need to pass through center
-its sequential so you need to do it fast before the eye moves too much

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14
Q

What is the pachymetry map produced by

A

Interpolation

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15
Q

Why is the OCT map unique

A
  • maps

- and cross sections

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16
Q

Where is the cornea thinnest?

A

Inferotemporal

17
Q

When you see a very thin cornea, what should yo expect, especially with it being very thin in the inferior

A

Keratoconus

18
Q

LASIK and OCT

A

Thin, flap=100 microns, need to follow the patient

19
Q

Pros of OCT

A
  • non contact
  • sublayer pach
  • 2d data
  • easy to acquire data, easy to standardize
  • applicable to post op assessment
  • measures through opacity
  • very high res
  • select meridional scans
20
Q

Cons of OCT

A
  • some developed for retinal imaging and thus require anterior segment adaptor
  • limited view
  • small penetration depth
  • can be slow (time domain)
  • software yet to be fully developed
21
Q

The main advantage of anterior segment OCT in comparison to scheimpflug imaging is

A

Detailed surface and morphological imaging

22
Q

What is the only tool we can measure the corneal epithelium with

23
Q

Compensatory nature of the epithelium

A

Not uniform, blanket that covers the stroma. If stroma not uniform, epithelium tries to mask it

24
Q

Epithelial thickness imaging

A

Somewhere uniform over the cornea, to approximately 50 microns

25
What is the most sensitive and telling measurement of corneal health
Corneal epithelium
26
The epithelial layer in a normal, not pathological Cornea, has a somehow uniform thickness of about 50 microns
True
27
The epithelial thickness distribution is affected by stromal thickness irregularities
True
28
The epithelial thickness distribution is affected by corneal pathology
True