Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Optics Block 8 > Biometry/ Ocular Imaging > Flashcards

Biometry/ Ocular Imaging Flashcards

1
Q

Measurement of basic data relating to the anatomical dimensions of the eye

A

Biometry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Is biometry quantitative or qualitative

A

Quantitative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Is ocular imaging qualitative or quantitative

A

Qualitative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Techniques that provide imaging of any part of the eye. Help document and facilitate diagnosis and treatment

A

Ocular imaging

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the oldest form of ocular imaging

A

Slit lamp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is now an integral part of the eye exam today

A

Ocular imaging

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

One dimensional depth plot

A

The A scan

  • A=axial
  • time of flight converted to distance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Axial resolution

A

-smallest distinction we can make along axis of propagation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Things we can measure with A scan

A
  • axial length
  • AC depth
  • corneal thickness
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is axial resolution dependent on

A

Wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Two-D plot for anatomical resemblance

A

B-scan

B for brightness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Combination of multiple A scans

A

B scan

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is all different between optical and acoustical

A

Wavelength, physics, results

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are some constraints on ocular imaging

A
  • absoprtion by tissue
  • wavelength
  • focal length
  • F#
  • resolution
  • depth range
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the F#

A

Related to the resolution of the eye

F# of the eye=8.3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is confocal good for

A

Powerful to show you cell morphology of the cornea

  • limited to thin layer
  • not as much depth
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Acoustical modalities of imaging

A
  • ultrasound waves (8-80MHz)
  • axial res dependent on wavelength
  • good penetration
  • high speed in dense material
  • signal dependent on change in impedance
  • res better for small wavelengths (higher freq)
  • time of flight measurement converted to depth
  • requires immersion coupling and is often contact technique
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What the main difference between acoustical vs optical modalities

A

Acoustical is contact, optical is noncontact

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Optical modalities

A
  • visible or infrared
  • axial res dependent on wavelength
  • poor penetration
  • signal depended on change in refractive index
  • slower speed in dense media
  • res is better for smaller wavelengths, typically better than acoustical
  • interferometric measurements converted to depth
  • no contact
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is a qualitative mode of imaging that detects tumors

A

MRI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Reflection of elastic wave due to different elastic modulus

A

Ultrasound/ultrasonography

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Is sound slower or faster in water

A

Faster

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Is light slower or faster in water

A

Slower

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

An ultrasound system operating at 10MHz has axial resolution of 120 microns. A high frequency US operates at 30 HMz. It’s axial res is

A

40 microns

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What kind of sound does ultrasound use
Very high frequency, 1000x higher than what humans can hear
26
What happens to wavelength when frequency increases
Decreases
27
What happens to resolution when wavelength is lower
Increased
28
A scan or B scan: quantitative, numbers
A scan
29
A scan or B scan: cross section, morphology, qualitative, shapes
B scan
30
Traditional ultrasound
- 8-20MHz sound waves - contact - no sublayer pach - low res, no 2D - not reliable peripherally - most common method used clinically - fast, simple technique - not accurate for edematous corneas - difficult to reposition
31
Pros of ultrasound
- penetration through opaque ocular media - portability - fast, simple - widely established, common clinical method
32
Cons of ultrasound
- repeatability, dissimulation to reposition, stadaradized - not reliable for periphery - possible risk of corneal abrasion - requires contact (need for anesthetic)
33
Traditionally employed for axial length measurements and corneal pachymetry
Ultrasound imaging
34
Uses a probe stylus and requires immersion coupling and applanation
Ultrasound
35
Helps assess various ocular and orbital diseases
Ultrasound
36
What can penetrate behind the iris
Ultrasound
37
A UBM system operates on a 30 micron wavelength, its axial resolution is
30 | Should be about the same as wavelght
38
In UBM, what is the reflection amplitude proportional to
Impedance gradient
39
Resolution of UBM
Dependent on wavelength; the higher the frequency, the better the resolution
40
What is the limitation of optica imaging
Can't penetrate tissue
41
Visualization of the iridocorneal angle, anterior lens, ciliary sulcus
UBM
42
LASIK flap and epithelial visualization
Epithelium is the small layer on top Flap is about 2x thick as epithelium CCT is the whole thing
43
When you add the epithelial thickness and the stromal thickness in the center, what do you get on the pentacam
CCT
44
Pros of arcscan UBM
- high res - epithelial and stromal thickness maps - corneal sublayer pachymetry, lamellar graft, and flap imaging
45
Cons of arcscan UBM
Patient uncomfortable data acquisition process - difficult to maintain centration, long acquisition time - significant capital acquisition cost
46
What's the difference between A scan and optical lower coherence reflectomerty
Optical low coherence reflectometyr is higher res
47
How is the time of flight measure in optical low coherence reflectometery
Interferometry
48
Examples of optical low coherence reflectometry
- IOL master | - LenSta Ls900
49
Infrared interferometry (similar to OCT), non contact
Optical low coherence reflectometry
50
Sublayer pachymetry and optical low coherence reflectomerty
Limited potential
51
What does optical low coherence reflectometry provide
A number of biometry data including axial length, anterior chamber depth, and pachymetry
52
Tight focusing and increased contrast through equal-optical length illumination and detection optical paths
Confocal microscopy
53
What is the confocal microscopy important for
Cellular morphology, detects microbial presence
54
Can confocal microscopy do pachymetry?
Yes, but VERY slowly
55
Things about confocal microscopy
-tight focus though corneal structures -contact -high res with sublayer pachymetry and cellular debris -2D =periphery requires repositioning -cellular morphology; detects microbial presence -high res, can quantify haze/scatter -slow, poor penetration of opacity
56
Which modality to use for intraorbital features
MRI
57
Which modality or use to image cell morphology
Confocal microscopy
58
Which modality to sue to image the epithelial layer
Ultrasound biomicroscopy
59
Which modality to use for quick pachymetry
Ultrasound
60
Which modality to use to image the vitreous when corneal opacity is present
If you want numbers: ultrasounds If you want pictures: UBM
61
Which modality to sue to image the ciliary sulcus structures
UBM
62
Which modality to use to measure axial length with the best precision
Optica low coherence interferometry

Optics Block 8 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions