ROUB Study Guide Questions with Verified
Correct Answers
If your biometry instrument has one pseudophakic eye-type setting, what is the only
IOL material that can accurately be measured?
Polymethyl methacrylate (PMMA)
If a gain setting is increased in order to obtain a 100% tall retina and sclera echo, what
type of cataract is being evaluated?
A dense cataract
What transducer frequency is generally used for a biometry A-scan probe?
10 MHz
What is the velocity of a biometer that only uses an average velocity to measure the
entire axial length?
1550 m/sec
What is one of the most important features of a biometer?
Display screen
What are the velocity settings for a phakic eye?
1532 m/sec for the aqueous; 1641 m/sec for the lens; and, 1532 m/sec for the vitreous cavity
What should the examiner do to reduce the presence of a reverberation echo created by
a dense cataract?
Reduce the gain
,What is the term for the electronic calipers that measure the distance between two or
more anatomic interfaces?
Gates
Of the following settings on the biometer (gain, gates, A-scan probe frequency, eye type,
and screen brightness), which cannot be changed by the examiner?
A-scan probe frequency
What is the proper sound velocity used to measure the distance between the anterior
and posterior lens interfaces in a phakic eye?
1641 m/sec
When performing immersion biometry, which gate in relation to the initial spike
represents the cornea?
Corneal gate is to the right of the initial spike
What is the possible cause for a biometry instrument to indicate an unusually short
measurement of a pseudophakic eye with a PMMA implant?
Multiple signal of the echo with improper identification of the retina
What biometer setting changes the degree of echo amplification?
Gain
What is the term for the relative strength or amplitude of an echo displayed on a
biometer?
Reflectivity
, When measuring an eye that has no crystalline lens, the instrument should be set on
which eye type?
Aphakic
What is the term for the "markers" or "cursors" displayed on the screen of a biometry
instrument that provide electronic measurements of distance between two or more
acoustic interfaces?
Gates
What is the term for the capacity of an ultrasound instrument to display two or more
interfaces that are very anatomically close to one another as separate echoes?
Resolution
How does increasing the gain setting on the biometer affect the display echo?
It increases the amount of amplification of the echo
What is the range of ophthalmic biometry frequencies?
8-12 MHz
How is the resolution affected when the gain is set at maximum?
The resolution is less
A non-focused sound beam is always utilized by which type of scan?
Diagnostic A-scan
What scan is used to obtain a two-dimensional image of the globe?
Diagnostic B-scan
What is the term for a one-dimensional amplitude scan?
Correct Answers
If your biometry instrument has one pseudophakic eye-type setting, what is the only
IOL material that can accurately be measured?
Polymethyl methacrylate (PMMA)
If a gain setting is increased in order to obtain a 100% tall retina and sclera echo, what
type of cataract is being evaluated?
A dense cataract
What transducer frequency is generally used for a biometry A-scan probe?
10 MHz
What is the velocity of a biometer that only uses an average velocity to measure the
entire axial length?
1550 m/sec
What is one of the most important features of a biometer?
Display screen
What are the velocity settings for a phakic eye?
1532 m/sec for the aqueous; 1641 m/sec for the lens; and, 1532 m/sec for the vitreous cavity
What should the examiner do to reduce the presence of a reverberation echo created by
a dense cataract?
Reduce the gain
,What is the term for the electronic calipers that measure the distance between two or
more anatomic interfaces?
Gates
Of the following settings on the biometer (gain, gates, A-scan probe frequency, eye type,
and screen brightness), which cannot be changed by the examiner?
A-scan probe frequency
What is the proper sound velocity used to measure the distance between the anterior
and posterior lens interfaces in a phakic eye?
1641 m/sec
When performing immersion biometry, which gate in relation to the initial spike
represents the cornea?
Corneal gate is to the right of the initial spike
What is the possible cause for a biometry instrument to indicate an unusually short
measurement of a pseudophakic eye with a PMMA implant?
Multiple signal of the echo with improper identification of the retina
What biometer setting changes the degree of echo amplification?
Gain
What is the term for the relative strength or amplitude of an echo displayed on a
biometer?
Reflectivity
, When measuring an eye that has no crystalline lens, the instrument should be set on
which eye type?
Aphakic
What is the term for the "markers" or "cursors" displayed on the screen of a biometry
instrument that provide electronic measurements of distance between two or more
acoustic interfaces?
Gates
What is the term for the capacity of an ultrasound instrument to display two or more
interfaces that are very anatomically close to one another as separate echoes?
Resolution
How does increasing the gain setting on the biometer affect the display echo?
It increases the amount of amplification of the echo
What is the range of ophthalmic biometry frequencies?
8-12 MHz
How is the resolution affected when the gain is set at maximum?
The resolution is less
A non-focused sound beam is always utilized by which type of scan?
Diagnostic A-scan
What scan is used to obtain a two-dimensional image of the globe?
Diagnostic B-scan
What is the term for a one-dimensional amplitude scan?
