COT Flashcards : Biometry 5%

Question 1

In A-scan biometry, which ocular measurement provides the axial length the of the globe?

A. Anterior corneal surface to anterior vitreous face
B. Anterior corneal surface to the retina
C. Pre-corneal tear film to posterior pole
D. Pre-corneal film to posterior vitreous face

Answer 1

B. Anterior corneal surface to the retina

Question 2

Ultrasound machines have a large number of switches and dials, most of which are rarely touched. What is the only change made during an average examination using the B-scan?
A. Sound intensity
B. LCD display
C. Pulse controls
D. Transducer

Answer 2

A. Sound intensity

Question 3

Immersion A-scan is generally more accurate than contact A-scan biometry due to
A. less eye movement
B. the use of more powerful ultrasound
C. better lubrication of the cornea
D. less corneal compression

Answer 3

D. less corneal compression

Question 4

What will distort the sound beam and render the resulting echo pattern almost unrecognizable?
A. use of topical anesthetic drops
B. Bubbles in the fluid bath
C. A posterior subcapsular cataract
D. The patient being reclined

Answer 4

B. Bubbles in the fluid bath

Question 5

How many dimensions does an A-scan produce in its display?
A. 0
B. 1
C. 2
D. 3

Answer 5

B. 1

Question 6

Contact A-scan biometry
A. is more accurate than immersion A-scan biometry
B. is used to measure corneal diameter
C. can be performed with patient upright or reclined
D. cannot be performed in an aphakic patient

Answer 6

C. can be performed with patient upright or reclined