Optics Lecture 6 Flashcards
Which modality to use for intraorbital features
MRI
Which modality to use to image cell morpholog
Confocal microscopy
Which modality to use to image the epithelial layer
Ultrasound biomicroscopy
Which modality to use for quick pachymetry
Ultrasound
Which modality to use to image the vitreous when corneal opacity is present
Ultrasound biomicroscopy
Which modality to use to image the ciliary body
Ultrasound biomicroscopy
Which modality to use to measure axial length with the BEST PRECISION
Optical low coherence interferometry
Is the a-scan quantitative or qualitative
Quantitative
What are the 3 axial data found from a-scan
Axial length
AC depth
Corneal thickness
Is the A-scan precise in measuring?
No, it is hard to be accurate
Is the b-scan quantitative or qualitative?
Qualitative
Acoustical modalities - what kind of waves?
Ultrasound
Acoustical modalities - how is the penetration
Good
Acoustical modalities - does it require immersion coupling
Yes - often a contact technique
Optical modalities - what kind of waves
Visible or infrared radiation
Optical modalities - how is the penetration?
Poor
Optical modalities - does it require immersion coupling?
No - no contact
Provides imaging of entire visual path
MRI
Does sound move faster or slower in air than water
Slower in air
Formula to use when comparing an ultrasound sys with a high frequency ultrasound sys
Multiply the MHz by axial resolution and divide by the other that only gave 1 number
Better resolution comes from what kind of wavelength
Shorter
A or B scan to get numerical values
A scan
A or B scan to get morphology/shapes
B scan
Is the ultrasound reliable for measuring peripheral thickness?
No
What modality measures things behind the iris and can penetrate through tissue that is normally covered by optical opacities
Ultrasound biomicroscopy
Can you see behind the iris when using an optical modality?
No
How thick is average corneal thickness
55-60 microns
In lasik, how thick is the flap on average
120 microns
Why is optical low-coherence reflectometry better than a-scan
More precise, accurate measurements and better resolution
Average axial length
22-24 mm
