CDOS PREP EXAM 2025 UPDATED QUESTIONS AND ANSWERS
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
vascularity assessment - CORRECT ANSWER✅✅eye is fixated steadily with probe stationary on the eye
convection movement - CORRECT ANSWER✅✅slow spontaneous movement of echoes on the screen
due to convection currents of fine particles or slow up and down motion of spikes on A scan or circular
motion of pointlike echoes on B scan
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
vascularity assessment - CORRECT ANSWER✅✅eye is fixated steadily with probe stationary on the eye
convection movement - CORRECT ANSWER✅✅slow spontaneous movement of echoes on the screen
due to convection currents of fine particles or slow up and down motion of spikes on A scan or circular
motion of pointlike echoes on B scan
