Retinal Imaging (M3)

Question 1

What are the four major things that the GDx report provides?

Answer 1

1. NFI
2. nerve fiber thickness map
3. deviation map
4. TSNIT

Question 2

With longer wavelength, does tissue penetration get deeper or shallower? 1. Is resolution better or worse? 2

Answer 2

1. deeper

2. worse

Question 3

What does the Heidelberg Retinal Tomograph (HRT) use as the laser?

Answer 3

scanning laser tomography

Question 4

What are the different types of tests that the HRT can run?

Answer 4

1. glaucoma module
2. retina module
3. cornea module

Question 5

What does a low gain during B-scan help view?

Answer 5

better resolution so more sensitive for subtle fundus elevations

Question 6

What is the laser type that scans the retina with a near infra red laser? 1. What is the overall test called? 2

Answer 6

1. scanning laser polarimetry

2. GDx VCC

Question 7

What does a high gain during B-scan help view?

Answer 7

weak signals like gross fundus lesions

Question 8

What is the frequency of UBM (ultrasound biomicroscopy)? 1. Ophthalmic B-scan? 2. Obsetetric ultrasound? 3

Answer 8

1. 20-50 MHz
2. 20 MHz
3. 3.5-7 MHz

Question 9

What type of OCT has a moving reference mirror that measures the time needed for light to be reflected back from the retina? 1. How many A-scans per second does it do? 2. What is the resolution? 3. What model of OCT uses this? 4

Answer 9

1. time domain (TD) OCT
2. 400
3. 10 um
4. Stratus

Question 10

What is the purpose of a B-scan?

Answer 10

detect disorders of the eye, usually in posterior segment pathology w/ dense media opacification

Question 11

What is the relationship of frequency to wavelength?

Answer 11

inc f = dec λ

Question 12

What does the gain alter in the B-scan?

Answer 12

amplitude (no frequency)

Question 13

What is the device used to make a HRT? 1. What is the software used? 2

Answer 13

1. confocal scanning laser ophthalmoscope

2. TruTrack software

Question 14

What type of OCT has simultaneous measurement of multiple wavelengths of light all over the spectrum? 1. How many A-scans per second does it do? 2. What is the resolution? 3. What model of OCT uses this? 4

Answer 14

1. spectral domain (SD) OCT
2. 40,000
3. 5 um
4. Cirrus

Question 15

What are the normal values for the nerve fiber indicator (NFI) for the GDx? 1. Borderline? 2. Abnormal? 3

Answer 15

1. 0-30
2. 31-50
3. 50 and over

Question 16

What should be done if the OCT scan looks upside down with poor detail?

Answer 16

patient too close so use mouse scroller to push image up until rights itself

Question 17

What are the four modes that we use for the OCT?

Answer 17

1. macular cube 512x128
2. HD 5 line Raster
3. Optic disc cube 200x200
4. anterior segment cube 512x128

Question 18

In the case of ocular surface disease, what can help to improve the OCT image?

Answer 18

artificial tears

Question 19

What is an A-scan used for?

Answer 19

one-dimensional amplitude modulation scan:

1. axial length
2. IOL calculation

Question 20

With shorter wavelength, does tissue penetration get deeper or shallower? 1. Is resolution better or worse? 2

Answer 20

1. shallower

2. better

Question 21

What are the accessible tissue for computerized retinal imaging?

Answer 21

1. RPE, choroid

2. cornea, sclera, iris, lens, AC angle

Question 22

What are the common uses of B-scan?

Answer 22

1. vit heme
2. suspected tumors
3. intraocular FB
4. RD
5. optic disc abnormalities
6. EOM disease
7. proptosis