CDOS Prep Exam Questions And Correct
Answers (Verified Answers) 2026
PVD - CORRECT ANSWER -Posterior vitreous detachment
4 positions to evaluate the macula - CORRECT ANSWER -1. Horizontal axial
2. Vertical transverse
3. Longitudinal
4. Vertical macula
Vertical Macula Scan - CORRECT ANSWER -obtained by displaying a vertical axial scan and
then directing the sound beam slightly temporally
Reverse macular scan - CORRECT ANSWER -performing a longitudinal exam of the nasal
meridian with the patient's gaze forward or slightly nasal with the probe placed so that it is
slightly overlapping the limbus; macular region is located in the lower aspect of the echogram
ultrasound - CORRECT ANSWER -an acoustic wave that consists of an oscillation of particles
within a medium
angle of sound incidence - CORRECT ANSWER -the angle at which the sound beam strikes an
interface
smooth flat interface - CORRECT ANSWER -will return almost all of an echo back to its source
creating a specular or mirror-like reflex (retinal surface)
smooth convex interface - CORRECT ANSWER -some of the echo will be reflected away from
its origin resulting in a weaker echo (dome shaped lesion)
,irregular/coarse interface - CORRECT ANSWER -part of the echo will be scattered resulting in a
weaker echo even if the transducer is perpendicular
reflectivity evaluation - CORRECT ANSWER -observed spike height of A scan and the
brightness of the B scan
reflectivity categorization - CORRECT ANSWER -determined by estimating the heights of the
spike on A scan as a percentage in relation to the vitreous baseline and the top of the initial spike
extremely low reflectivity - CORRECT ANSWER -0-5%
low reflectivity - CORRECT ANSWER -5-40%
medium reflectivity - CORRECT ANSWER -40-60%
medium high reflectivity - CORRECT ANSWER -60-80%
high reflectivity - CORRECT ANSWER -80-100%
internal structure - CORRECT ANSWER -refers to degree of variation of histologic architecture
in a masslike lesion and is evaluated by noting differences in the height and length of the A scan
spikes and the differences in echodensity on B scan
regular internal structure - CORRECT ANSWER -little or no variation in the height and length
of spikes on A scan; uniform appearance on B scan
irregular internal structure - CORRECT ANSWER -marked differences in echo appearance
, sound attenuation - CORRECT ANSWER -occurs when sound energy is scattered, reflected, or
absorbed by the medium indicated on B scan as a decrease in the brightness of echoes or a
reduction in spike height on A scan
posterior shadowing - CORRECT ANSWER -absence of echoes posterior to the structure due to
sound attenuation
Quantitative echography type II - CORRECT ANSWER -method for differentiating a retinal
detachment from a vitreous membrane:
1.Horizontal line is placed in the middle of the screen
2.Probe is placed perpendicular to the membrane
3.Probe is placed perpendicular to the sclera
4.The decibel level is decreased until the spike from these surfaces touches but does not surpass
the horizontal line
5.Difference in decibel setting required to display the membrane and the sclera at the specific
spike level may help differentiate retina from vitreous membranes
*6-15db = retina
*>20db = vitreous membrane
aftermovement - CORRECT ANSWER -the motion of the lesion echoes before, during, and
immediately after an eye movement
horizontal spike movement - CORRECT ANSWER -represents lateral motion and can be
observed on B scan
vertical spike movement - CORRECT ANSWER -caused by minimal change in position of the
lesion relative to the sound beam and is usually not appreciable on B scan
vascularity - CORRECT ANSWER -fast spontaneous motion of echoes representing bloodflow
within blood vessels displayed as low amplitude continuous flickering of the internal lesion
spikes on A scan
Answers (Verified Answers) 2026
PVD - CORRECT ANSWER -Posterior vitreous detachment
4 positions to evaluate the macula - CORRECT ANSWER -1. Horizontal axial
2. Vertical transverse
3. Longitudinal
4. Vertical macula
Vertical Macula Scan - CORRECT ANSWER -obtained by displaying a vertical axial scan and
then directing the sound beam slightly temporally
Reverse macular scan - CORRECT ANSWER -performing a longitudinal exam of the nasal
meridian with the patient's gaze forward or slightly nasal with the probe placed so that it is
slightly overlapping the limbus; macular region is located in the lower aspect of the echogram
ultrasound - CORRECT ANSWER -an acoustic wave that consists of an oscillation of particles
within a medium
angle of sound incidence - CORRECT ANSWER -the angle at which the sound beam strikes an
interface
smooth flat interface - CORRECT ANSWER -will return almost all of an echo back to its source
creating a specular or mirror-like reflex (retinal surface)
smooth convex interface - CORRECT ANSWER -some of the echo will be reflected away from
its origin resulting in a weaker echo (dome shaped lesion)
,irregular/coarse interface - CORRECT ANSWER -part of the echo will be scattered resulting in a
weaker echo even if the transducer is perpendicular
reflectivity evaluation - CORRECT ANSWER -observed spike height of A scan and the
brightness of the B scan
reflectivity categorization - CORRECT ANSWER -determined by estimating the heights of the
spike on A scan as a percentage in relation to the vitreous baseline and the top of the initial spike
extremely low reflectivity - CORRECT ANSWER -0-5%
low reflectivity - CORRECT ANSWER -5-40%
medium reflectivity - CORRECT ANSWER -40-60%
medium high reflectivity - CORRECT ANSWER -60-80%
high reflectivity - CORRECT ANSWER -80-100%
internal structure - CORRECT ANSWER -refers to degree of variation of histologic architecture
in a masslike lesion and is evaluated by noting differences in the height and length of the A scan
spikes and the differences in echodensity on B scan
regular internal structure - CORRECT ANSWER -little or no variation in the height and length
of spikes on A scan; uniform appearance on B scan
irregular internal structure - CORRECT ANSWER -marked differences in echo appearance
, sound attenuation - CORRECT ANSWER -occurs when sound energy is scattered, reflected, or
absorbed by the medium indicated on B scan as a decrease in the brightness of echoes or a
reduction in spike height on A scan
posterior shadowing - CORRECT ANSWER -absence of echoes posterior to the structure due to
sound attenuation
Quantitative echography type II - CORRECT ANSWER -method for differentiating a retinal
detachment from a vitreous membrane:
1.Horizontal line is placed in the middle of the screen
2.Probe is placed perpendicular to the membrane
3.Probe is placed perpendicular to the sclera
4.The decibel level is decreased until the spike from these surfaces touches but does not surpass
the horizontal line
5.Difference in decibel setting required to display the membrane and the sclera at the specific
spike level may help differentiate retina from vitreous membranes
*6-15db = retina
*>20db = vitreous membrane
aftermovement - CORRECT ANSWER -the motion of the lesion echoes before, during, and
immediately after an eye movement
horizontal spike movement - CORRECT ANSWER -represents lateral motion and can be
observed on B scan
vertical spike movement - CORRECT ANSWER -caused by minimal change in position of the
lesion relative to the sound beam and is usually not appreciable on B scan
vascularity - CORRECT ANSWER -fast spontaneous motion of echoes representing bloodflow
within blood vessels displayed as low amplitude continuous flickering of the internal lesion
spikes on A scan
