ROUB EXAM AND STUDY GUIDE LATEST
2026 TEST BANK| COMPLETE 250
ACTUAL EXAM QUESTIONS AND
CORRECT VERIFIED ANSWERS/ ALREADY
GRADED A+ (BRAND NEW!!)
If your biometry instrument has one psuedophakic eye-type setting. What is the
only IOL material that can be accurately measured ? -
✔✔✔ANSW✔✔..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 ? - ✔✔✔ANSW✔✔..A dense cataract
What transducer frequency is generally used for a biometry A-Scan probe ? -
✔✔✔ANSW✔✔..10 MHz
What is the velocity of a biometer that only uses an average velocity to measure
the entire axial length ? - ✔✔✔ANSW✔✔..1550 m/sec
What is one of the most important features of a biometer ? - ✔✔✔ANSW✔✔..The
display screen
What are the velocity settings for a phakic eye ? - ✔✔✔ANSW✔✔..(+) Aqueous :
1532 m/s
(+) Crystalline Lens : 1641 m/s
(+) Vitreous : 1532 m/s
What should the examiner do to reduce the presence of a reverberation echo
created by a dense cataract ? - ✔✔✔ANSW✔✔..Reduce the gain
What is the term for the electronic calipers that measure the distance between two
or more anatomic interfaces ? - ✔✔✔ANSW✔✔..Gates
,Of the following settings on the biometer screen (gain, gates, A-scan probe
frequency, eye type and screen brightness), which cannot be changed by the
examiner ? - ✔✔✔ANSW✔✔..A-Scan probe frequency
What is the proper sound velocity used to measure the distance between the
anterior ans posterior lens interfaces in a phakic eye ? - ✔✔✔ANSW✔✔..1641
m/s
when performing immersion biometry, which gate in relation to the initial spike
represents the cornea ? - ✔✔✔ANSW✔✔..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 psuedophakic eye with a PMMA implant ? -
✔✔✔ANSW✔✔..Multiple signal of the echo with improper identification of the
retina
What biometer setting changes the degree of echo amplification ? -
✔✔✔ANSW✔✔..Gain
What is the term for the relative strength or amplitude of an echo displayed on a
biometer ? - ✔✔✔ANSW✔✔..Reflectivity
When measuring an eye that has no crystalline lens, the instrument should be set
on what eye type ? - ✔✔✔ANSW✔✔..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 ? - ✔✔✔ANSW✔✔..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 ?
- ✔✔✔ANSW✔✔..Resolution
How does increasing the gain setting on the biometer affect the displayed echo ? -
✔✔✔ANSW✔✔..It increases the amount of amplification of the echo
,What is the range of ophthalmic biometry frequencies ? - ✔✔✔ANSW✔✔..8 to 12
MHz
How is resolution affected when the gain is set at maximum ? -
✔✔✔ANSW✔✔..The resolution is less
A non-focused sound beam is always utilized by which type of scan ? -
✔✔✔ANSW✔✔..Diagnostic A-Scan
What scan is used to obtain a two-dimensional image of the globe ? -
✔✔✔ANSW✔✔..Diagnostic B-Scan
What is the term for a one-dimensional amplitude scan ? - ✔✔✔ANSW✔✔..A-
Scan
The strength of an echo is dependent on what three factors ? -
✔✔✔ANSW✔✔..Gain, difference in density, and proper alignment
What type of scan uses Prager or scleral shells ? - ✔✔✔ANSW✔✔..Immersion A-
Scan
How often should the filter of a biometry instrument be vacuumed ? -
✔✔✔ANSW✔✔..Once a month
Measurement of axial length of the eye, thickness of an extraocular muscle, and
tumor height are all within the definition of what term ? -
✔✔✔ANSW✔✔..Biometry
What is the leading cause of an unplanned, post-operative refractive error ? -
✔✔✔ANSW✔✔..An error in the measurement of axial length
An error of 0.1 mm in the axial length measurement can result in a post-operative
refractive error of how many diopters ? - ✔✔✔ANSW✔✔..0.25 D
If multiple axial length readings are taken from a single eye, each measurement
should be within how many millimeters ? - ✔✔✔ANSW✔✔..0.2 mm
, The difference in axial length between two eyes should measure within how many
millimeters ? - ✔✔✔ANSW✔✔..0.3 mm
What are two techniques for measuring axial length ? - ✔✔✔ANSW✔✔..Contact
& Immersion
When performing contact biometry, steps should be taken to minimize what
factors? - ✔✔✔ANSW✔✔..Corneal compression and corneal abrasions
What are possible causes of a short measurement in biometry ? -
✔✔✔ANSW✔✔..(+) Gain is set too high
(+) Corneal compression
(+) Air bubble adherent to the transducer
(+) Corneal gate to the right of the corneal spike
(+) Retinal gate too far left of the retinal spike
(+) Lens measured too thin
(+) Misalignment of the sound beam
(+) Low sound velocity
What are possible causes of a long measurement in biometry ? -
✔✔✔ANSW✔✔..(+) Gain is set too low
(+) Fluid bridge (contact method)
(+) Air bubble in fluid bath (immersion method)
(+) Retinal gate too far right of the retinal spike
(+) Lens measured too thick
(+) Misalignment of the sound beam
(+) Sound velocity too fast
How is corneal compression determined ? - ✔✔✔ANSW✔✔..AC depth and/or
distance between initial spike and anterior lens spike
What is more likely to occur during contact (hand-held) method biometry ? -
✔✔✔ANSW✔✔..Corneal depression
What are three advantages of A-Scan immersion technique ? -
✔✔✔ANSW✔✔..(+) Proper sound beam alignment
(+) No corneal compression
(+) Corneal and crystalline lens thickness measured
2026 TEST BANK| COMPLETE 250
ACTUAL EXAM QUESTIONS AND
CORRECT VERIFIED ANSWERS/ ALREADY
GRADED A+ (BRAND NEW!!)
If your biometry instrument has one psuedophakic eye-type setting. What is the
only IOL material that can be accurately measured ? -
✔✔✔ANSW✔✔..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 ? - ✔✔✔ANSW✔✔..A dense cataract
What transducer frequency is generally used for a biometry A-Scan probe ? -
✔✔✔ANSW✔✔..10 MHz
What is the velocity of a biometer that only uses an average velocity to measure
the entire axial length ? - ✔✔✔ANSW✔✔..1550 m/sec
What is one of the most important features of a biometer ? - ✔✔✔ANSW✔✔..The
display screen
What are the velocity settings for a phakic eye ? - ✔✔✔ANSW✔✔..(+) Aqueous :
1532 m/s
(+) Crystalline Lens : 1641 m/s
(+) Vitreous : 1532 m/s
What should the examiner do to reduce the presence of a reverberation echo
created by a dense cataract ? - ✔✔✔ANSW✔✔..Reduce the gain
What is the term for the electronic calipers that measure the distance between two
or more anatomic interfaces ? - ✔✔✔ANSW✔✔..Gates
,Of the following settings on the biometer screen (gain, gates, A-scan probe
frequency, eye type and screen brightness), which cannot be changed by the
examiner ? - ✔✔✔ANSW✔✔..A-Scan probe frequency
What is the proper sound velocity used to measure the distance between the
anterior ans posterior lens interfaces in a phakic eye ? - ✔✔✔ANSW✔✔..1641
m/s
when performing immersion biometry, which gate in relation to the initial spike
represents the cornea ? - ✔✔✔ANSW✔✔..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 psuedophakic eye with a PMMA implant ? -
✔✔✔ANSW✔✔..Multiple signal of the echo with improper identification of the
retina
What biometer setting changes the degree of echo amplification ? -
✔✔✔ANSW✔✔..Gain
What is the term for the relative strength or amplitude of an echo displayed on a
biometer ? - ✔✔✔ANSW✔✔..Reflectivity
When measuring an eye that has no crystalline lens, the instrument should be set
on what eye type ? - ✔✔✔ANSW✔✔..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 ? - ✔✔✔ANSW✔✔..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 ?
- ✔✔✔ANSW✔✔..Resolution
How does increasing the gain setting on the biometer affect the displayed echo ? -
✔✔✔ANSW✔✔..It increases the amount of amplification of the echo
,What is the range of ophthalmic biometry frequencies ? - ✔✔✔ANSW✔✔..8 to 12
MHz
How is resolution affected when the gain is set at maximum ? -
✔✔✔ANSW✔✔..The resolution is less
A non-focused sound beam is always utilized by which type of scan ? -
✔✔✔ANSW✔✔..Diagnostic A-Scan
What scan is used to obtain a two-dimensional image of the globe ? -
✔✔✔ANSW✔✔..Diagnostic B-Scan
What is the term for a one-dimensional amplitude scan ? - ✔✔✔ANSW✔✔..A-
Scan
The strength of an echo is dependent on what three factors ? -
✔✔✔ANSW✔✔..Gain, difference in density, and proper alignment
What type of scan uses Prager or scleral shells ? - ✔✔✔ANSW✔✔..Immersion A-
Scan
How often should the filter of a biometry instrument be vacuumed ? -
✔✔✔ANSW✔✔..Once a month
Measurement of axial length of the eye, thickness of an extraocular muscle, and
tumor height are all within the definition of what term ? -
✔✔✔ANSW✔✔..Biometry
What is the leading cause of an unplanned, post-operative refractive error ? -
✔✔✔ANSW✔✔..An error in the measurement of axial length
An error of 0.1 mm in the axial length measurement can result in a post-operative
refractive error of how many diopters ? - ✔✔✔ANSW✔✔..0.25 D
If multiple axial length readings are taken from a single eye, each measurement
should be within how many millimeters ? - ✔✔✔ANSW✔✔..0.2 mm
, The difference in axial length between two eyes should measure within how many
millimeters ? - ✔✔✔ANSW✔✔..0.3 mm
What are two techniques for measuring axial length ? - ✔✔✔ANSW✔✔..Contact
& Immersion
When performing contact biometry, steps should be taken to minimize what
factors? - ✔✔✔ANSW✔✔..Corneal compression and corneal abrasions
What are possible causes of a short measurement in biometry ? -
✔✔✔ANSW✔✔..(+) Gain is set too high
(+) Corneal compression
(+) Air bubble adherent to the transducer
(+) Corneal gate to the right of the corneal spike
(+) Retinal gate too far left of the retinal spike
(+) Lens measured too thin
(+) Misalignment of the sound beam
(+) Low sound velocity
What are possible causes of a long measurement in biometry ? -
✔✔✔ANSW✔✔..(+) Gain is set too low
(+) Fluid bridge (contact method)
(+) Air bubble in fluid bath (immersion method)
(+) Retinal gate too far right of the retinal spike
(+) Lens measured too thick
(+) Misalignment of the sound beam
(+) Sound velocity too fast
How is corneal compression determined ? - ✔✔✔ANSW✔✔..AC depth and/or
distance between initial spike and anterior lens spike
What is more likely to occur during contact (hand-held) method biometry ? -
✔✔✔ANSW✔✔..Corneal depression
What are three advantages of A-Scan immersion technique ? -
✔✔✔ANSW✔✔..(+) Proper sound beam alignment
(+) No corneal compression
(+) Corneal and crystalline lens thickness measured
