CDOS CERTIFIED DIAGNOSTIC OPHTHALMIC
SONOGRAPHER PRACTICE EXAM (2026
UPDATED) | VERIFIED QUESTIONS AND
CORRECT ANSWERS WITH DETAILED
EXPLANATIONS | INSTANT DOWNLOAD PDF
STUDY GUIDE
CDOS CERTIFIED DIAGNOSTIC OPHTHALMIC SONOGRAPHER PRACTICE EXAM
(2026)
• This practice exam contains 200 verified questions with correct answers and
detailed EXPERT RATIONALE, designed to mirror the actual CDOS certification
exam format and difficulty level.
• Study by attempting each question independently before revealing the answer —
use the highlighted correct options and EXPERT RATIONALE to reinforce
understanding and identify weak areas for focused review.
1. Which ultrasound frequency range is most commonly used in ophthalmic
diagnostic imaging?
A. 1–3 MHz
B. 3–5 MHz
C. 8–10 MHz
D. 10–20 MHz
E. 8–20 MHz (most commonly 10 MHz)
CORRECT ANSWER: E. 8–20 MHz (most commonly 10 MHz)
EXPERT RATIONALE: Ophthalmic ultrasound typically uses high frequencies in
the range of 8–20 MHz, with 10 MHz being the standard for B-scan and A-scan
imaging. Higher frequencies provide better axial resolution necessary for the small
structures of the eye, though they have less penetration depth.
,2. In A-scan ultrasonography, the display represents:
A. A two-dimensional cross-sectional image
B. A color-coded flow map
C. A three-dimensional reconstruction
D. A one-dimensional amplitude display over time
E. A brightness-modulated image
CORRECT ANSWER: D. A one-dimensional amplitude display over time
EXPERT RATIONALE: A-scan (amplitude scan) displays echoes as vertical spikes
along a horizontal time axis. The height of each spike represents the amplitude
(strength) of the returning echo. This is used to measure distances and tissue
characteristics within the eye.
3. B-scan ultrasonography produces:
A. One-dimensional amplitude spikes
B. Doppler frequency shifts
C. A two-dimensional brightness-modulated image
D. A spectral waveform
E. A volumetric reconstruction
CORRECT ANSWER: C. A two-dimensional brightness-modulated image
EXPERT RATIONALE: B-scan (brightness scan) converts echo amplitudes into
dots of varying brightness on a two-dimensional display, creating a cross-sectional
image of the eye and orbit. This allows visualization of structures, masses, and
pathology in real time.
4. The axial resolution of an ultrasound system is primarily determined by:
A. Beam width
,B. Focal zone depth
C. Pulse length (spatial pulse length)
D. Transducer diameter
E. Gain settings
CORRECT ANSWER: C. Pulse length (spatial pulse length)
EXPERT RATIONALE: Axial resolution refers to the ability to distinguish two
structures lying along the beam axis. It is determined by the spatial pulse length —
shorter pulses yield better axial resolution. Higher frequencies produce shorter
wavelengths and shorter pulse lengths, improving axial resolution.
5. Lateral resolution in ultrasound imaging is best improved by:
A. Increasing gain
B. Decreasing frequency
C. Increasing depth
D. Focusing the beam at the area of interest
E. Using a larger transducer
CORRECT ANSWER: D. Focusing the beam at the area of interest
EXPERT RATIONALE: Lateral resolution depends on beam width at the point of
interest. Focusing the beam narrows it at the focal zone, improving the ability to
distinguish two adjacent structures perpendicular to the beam axis.
6. The speed of sound used as a standard in ophthalmic ultrasound through
ocular tissues is approximately:
A. 1,532 m/s
B. 1,550 m/s
C. 1,480 m/s
, D. 1,620 m/s
E. 1,700 m/s
CORRECT ANSWER: B. 1,550 m/s
EXPERT RATIONALE: The standard average speed of sound used in ophthalmic
ultrasound biometry is approximately 1,550 m/s through the eye. Different tissues
have different sound velocities (e.g., lens ~1,641 m/s, vitreous ~1,532 m/s), but
1,550 m/s is the accepted average for total axial length measurement.
7. Which of the following best describes acoustic impedance?
A. The frequency at which a transducer operates
B. The speed of sound in a vacuum
C. The product of tissue density and the speed of sound
D. The ratio of reflected to transmitted sound
E. The energy absorbed per unit depth
CORRECT ANSWER: C. The product of tissue density and the speed of sound
EXPERT RATIONALE: Acoustic impedance (Z) = density (ρ) × speed of sound (c).
It determines how much sound is reflected or transmitted at interfaces between
tissues. Greater differences in acoustic impedance between two media result in
greater reflection at their interface.
8. When sound travels from a medium of low acoustic impedance to one of
high acoustic impedance:
A. All sound is absorbed
B. All sound is transmitted
C. A significant portion is reflected back
D. Sound changes frequency
SONOGRAPHER PRACTICE EXAM (2026
UPDATED) | VERIFIED QUESTIONS AND
CORRECT ANSWERS WITH DETAILED
EXPLANATIONS | INSTANT DOWNLOAD PDF
STUDY GUIDE
CDOS CERTIFIED DIAGNOSTIC OPHTHALMIC SONOGRAPHER PRACTICE EXAM
(2026)
• This practice exam contains 200 verified questions with correct answers and
detailed EXPERT RATIONALE, designed to mirror the actual CDOS certification
exam format and difficulty level.
• Study by attempting each question independently before revealing the answer —
use the highlighted correct options and EXPERT RATIONALE to reinforce
understanding and identify weak areas for focused review.
1. Which ultrasound frequency range is most commonly used in ophthalmic
diagnostic imaging?
A. 1–3 MHz
B. 3–5 MHz
C. 8–10 MHz
D. 10–20 MHz
E. 8–20 MHz (most commonly 10 MHz)
CORRECT ANSWER: E. 8–20 MHz (most commonly 10 MHz)
EXPERT RATIONALE: Ophthalmic ultrasound typically uses high frequencies in
the range of 8–20 MHz, with 10 MHz being the standard for B-scan and A-scan
imaging. Higher frequencies provide better axial resolution necessary for the small
structures of the eye, though they have less penetration depth.
,2. In A-scan ultrasonography, the display represents:
A. A two-dimensional cross-sectional image
B. A color-coded flow map
C. A three-dimensional reconstruction
D. A one-dimensional amplitude display over time
E. A brightness-modulated image
CORRECT ANSWER: D. A one-dimensional amplitude display over time
EXPERT RATIONALE: A-scan (amplitude scan) displays echoes as vertical spikes
along a horizontal time axis. The height of each spike represents the amplitude
(strength) of the returning echo. This is used to measure distances and tissue
characteristics within the eye.
3. B-scan ultrasonography produces:
A. One-dimensional amplitude spikes
B. Doppler frequency shifts
C. A two-dimensional brightness-modulated image
D. A spectral waveform
E. A volumetric reconstruction
CORRECT ANSWER: C. A two-dimensional brightness-modulated image
EXPERT RATIONALE: B-scan (brightness scan) converts echo amplitudes into
dots of varying brightness on a two-dimensional display, creating a cross-sectional
image of the eye and orbit. This allows visualization of structures, masses, and
pathology in real time.
4. The axial resolution of an ultrasound system is primarily determined by:
A. Beam width
,B. Focal zone depth
C. Pulse length (spatial pulse length)
D. Transducer diameter
E. Gain settings
CORRECT ANSWER: C. Pulse length (spatial pulse length)
EXPERT RATIONALE: Axial resolution refers to the ability to distinguish two
structures lying along the beam axis. It is determined by the spatial pulse length —
shorter pulses yield better axial resolution. Higher frequencies produce shorter
wavelengths and shorter pulse lengths, improving axial resolution.
5. Lateral resolution in ultrasound imaging is best improved by:
A. Increasing gain
B. Decreasing frequency
C. Increasing depth
D. Focusing the beam at the area of interest
E. Using a larger transducer
CORRECT ANSWER: D. Focusing the beam at the area of interest
EXPERT RATIONALE: Lateral resolution depends on beam width at the point of
interest. Focusing the beam narrows it at the focal zone, improving the ability to
distinguish two adjacent structures perpendicular to the beam axis.
6. The speed of sound used as a standard in ophthalmic ultrasound through
ocular tissues is approximately:
A. 1,532 m/s
B. 1,550 m/s
C. 1,480 m/s
, D. 1,620 m/s
E. 1,700 m/s
CORRECT ANSWER: B. 1,550 m/s
EXPERT RATIONALE: The standard average speed of sound used in ophthalmic
ultrasound biometry is approximately 1,550 m/s through the eye. Different tissues
have different sound velocities (e.g., lens ~1,641 m/s, vitreous ~1,532 m/s), but
1,550 m/s is the accepted average for total axial length measurement.
7. Which of the following best describes acoustic impedance?
A. The frequency at which a transducer operates
B. The speed of sound in a vacuum
C. The product of tissue density and the speed of sound
D. The ratio of reflected to transmitted sound
E. The energy absorbed per unit depth
CORRECT ANSWER: C. The product of tissue density and the speed of sound
EXPERT RATIONALE: Acoustic impedance (Z) = density (ρ) × speed of sound (c).
It determines how much sound is reflected or transmitted at interfaces between
tissues. Greater differences in acoustic impedance between two media result in
greater reflection at their interface.
8. When sound travels from a medium of low acoustic impedance to one of
high acoustic impedance:
A. All sound is absorbed
B. All sound is transmitted
C. A significant portion is reflected back
D. Sound changes frequency
