Download [CDOS] Certified Diagnostic Ophthalmic Sonographer CDOS Exam Guide and more Exams Technology in PDF only on Docsity!
Sonographer CDOS Exam Guide | Exam Focused
MCQs (2026)
Question 1. Which of the following best describes the relationship between ultrasound frequency and axial resolution in ophthalmic imaging? A) Higher frequency decreases axial resolution B) Higher frequency improves axial resolution C) Frequency does not affect axial resolution D) Lower frequency improves axial resolution Answer: B Explanation: Axial resolution is directly proportional to the pulse length, which shortens as frequency increases, yielding finer detail along the beam axis. Question 2. In ocular ultrasound, what is the primary effect of increasing the transducer frequency from 10 MHz to 20 MHz? A) Greater tissue penetration with reduced detail B) Reduced penetration depth but enhanced image detail C) No change in penetration or resolution D) Increased attenuation without affecting resolution Answer: B Explanation: Higher frequencies are absorbed more rapidly, limiting depth but providing superior spatial resolution. Question 3. Which acoustic property determines the speed at which sound travels through the vitreous humor? A) Density B) Elasticity (bulk modulus) C) Attenuation coefficient
Sonographer CDOS Exam Guide | Exam Focused
MCQs (2026)
D) Acoustic impedance Answer: B Explanation: The speed of sound is governed by the medium’s elasticity; vitreous humor’s low elasticity yields a speed of ~1530 m/s. Question 4. The angle of incidence that maximizes echo return from a planar retinal surface is: A) 0° (perpendicular) B) 30° C) 45° D) 90° (parallel) Answer: A Explanation: When the ultrasound beam strikes a surface perpendicularly, reflection is strongest, producing the brightest echo. Question 5. Which of the following ultrasound artifacts is produced when an echo bounces repeatedly between two strong reflectors? A) Shadowing B) Reverberation C) Comet‑tail D) Mirror image Answer: B Explanation: Reverberation occurs when echoes repeatedly reflect between two interfaces, creating equally spaced linear artifacts.
Sonographer CDOS Exam Guide | Exam Focused
MCQs (2026)
Explanation: ALARA (As Low As Reasonably Achievable) emphasizes minimizing acoustic exposure while maintaining diagnostic quality. Question 9. Which piezoelectric material is most commonly used in high‑frequency ophthalmic transducers? A) Lead zirconate titanate (PZT) B) Quartz crystal C) Polyvinylidene fluoride (PVDF) D) Barium titanate Answer: A Explanation: PZT offers high coupling efficiency and is standard in ophthalmic probes up to 20 MHz. Question 10. A‑scan ultrasonography differs from B‑scan primarily because it provides: A) Two‑dimensional cross‑sectional images B) Quantitative echo amplitude versus depth data C) Real‑time video loops D) Color Doppler flow information Answer: B Explanation: A‑scan displays a one‑dimensional graph of echo spikes versus depth, useful for biometric measurements. Question 11. Which probe type is most appropriate for imaging the anterior segment with a resolution of ≤0.1 mm? A) 10 MHz linear probe
Sonographer CDOS Exam Guide | Exam Focused
MCQs (2026)
B) 20 MHz high‑frequency probe C) 5 MHz convex probe D) 2 MHz phased‑array probe Answer: B Explanation: A 20 MHz probe provides the necessary high resolution for detailed anterior segment structures. Question 12. In ultrasound biometry, immersion A‑scan is preferred over contact A‑scan because: A) It eliminates corneal compression, improving axial length accuracy B) It requires less sterile technique C) It provides color flow data D) It uses lower frequency waves for deeper penetration Answer: A Explanation: Immersion technique avoids corneal indentation, yielding more reliable axial length measurements. Question 13. The “mirror image” artifact in ocular ultrasound is most commonly seen when imaging: A) The optic nerve head B) The posterior lens capsule C) A highly reflective choroidal melanoma near the sclera D) A retinal detachment adjacent to the vitreous base Answer: C
Sonographer CDOS Exam Guide | Exam Focused
MCQs (2026)
C) Medium‑to‑high internal reflectivity with a “mushroom” shape and acoustic hollowness D) Uniformly echogenic, flat lesion confined to the retinal surface Answer: C Explanation: Choroidal melanoma typically exhibits medium‑to‑high reflectivity, a mushroom or dome shape, and internal acoustic hollowness due to necrosis. Question 17. Asteroid hyalosis is identified on B‑scan by: A) Large, dense shadowing throughout the vitreous B) Numerous mobile, highly reflective, comet‑tail artifacts throughout the vitreous body C) A single, fixed, highly reflective mass attached to the retina D) Diffuse low‑level echogenicity without discrete artifacts Answer: B Explanation: Calcium‑laden asteroid bodies produce characteristic comet‑tail artifacts that move with eye motion. Question 18. Which ocular structure provides the strongest acoustic interface for generating a bright echo in A‑scan? A) Corneal epithelium B) Lens capsule C) Vitreous body D) Sclera Answer: B Explanation: The lens capsule’s high acoustic impedance mismatch with surrounding vitreous produces a prominent spike on A‑scan.
Sonographer CDOS Exam Guide | Exam Focused
MCQs (2026)
Question 19. When measuring intraocular lens (IOL) power, which biometric parameter is most critical? A) Corneal thickness B) Axial length C) Anterior chamber depth D) Lens curvature Answer: B Explanation: Axial length is the primary determinant of IOL power calculations; small errors can cause significant refractive surprises. Question 20. In a patient with a suspected intra‑ocular foreign body (IOFB), which ultrasound characteristic confirms a metallic fragment? A) Highly echogenic, round object with posterior acoustic shadowing and reverberation B) Low‑level, anechoic area without shadowing C) Uniformly hyperechoic mass with no shadowing D) Mobile, linear echogenic strand within the vitreous Answer: A Explanation: Metallic IOFBs generate strong echoes and cast dense posterior shadows with reverberation artifacts. Question 21. Which of the following best describes the purpose of the “focus zone” adjustment on an ophthalmic ultrasound machine? A) To change the transducer frequency B) To position the point of maximum lateral resolution at the depth of interest C) To increase overall gain uniformly
Sonographer CDOS Exam Guide | Exam Focused
MCQs (2026)
Question 24. In the context of ocular trauma, a “lens subluxation” on ultrasound appears as: A) Complete absence of the lens echo B) A displaced lens echo with an abnormal orientation relative to the visual axis C) A hyper‑reflective, static mass within the vitreous cavity D) Multiple small, mobile echoes throughout the anterior chamber Answer: B Explanation: Subluxated lenses display an off‑center, tilted echo indicating displacement from its normal position. Question 25. Which of the following best explains why a “pseudotumor” artifact may be mistaken for a retinal mass? A) It creates a true shadow that mimics a lesion B) It produces a focal area of increased gain that looks like a mass C) It is a reverberation artifact that appears as a solid, well‑defined structure D) It results from beam‑width artifacts that generate a false echo near the retina Answer: D Explanation: Beam‑width artifacts can generate spurious echoes adjacent to the retina, simulating a mass. Question 26. During a B‑scan, the presence of “posterior acoustic enhancement” indicates: A) Highly attenuating calcified lesion B) Fluid‑filled cavity such as a vitreous hemorrhage C) Dense fibrous tissue D) Air bubbles within the eye
Sonographer CDOS Exam Guide | Exam Focused
MCQs (2026)
Answer: B Explanation: Fluid transmits sound with little attenuation, leading to increased echo amplitude behind the fluid (enhancement). Question 27. Which of the following is the most appropriate patient positioning for a pediatric ocular ultrasound? A) Supine with the head tilted upward B) Seated upright with chin up C) Supine with the head turned 30° opposite the eye being scanned D) Prone with the eye facing downward Answer: C Explanation: Turning the head away from the scanned eye provides better acoustic coupling and reduces motion in children. Question 28. In an A‑scan trace, a sharp, high‑amplitude spike at a shallow depth most likely represents: A) Vitreous cavity B) Corneal surface C) Retinal pigment epithelium D) Choroidal melanoma Answer: B Explanation: The cornea’s high acoustic impedance difference from air produces a strong, early spike. Question 29. Which safety measure is essential when performing ultrasound on a patient with an open globe injury?
Sonographer CDOS Exam Guide | Exam Focused
MCQs (2026)
Explanation: Axial resolution is determined by pulse length (frequency), while lateral resolution is governed by beam width (focus). Question 32. In the evaluation of a suspected choroidal hemangioma, the typical B‑scan finding is: A) Highly reflective, calcified mass with posterior shadowing B) Low‑reflectivity, cystic lesion with fluid‑filled appearance C) Moderately reflective, dome‑shaped lesion with intrinsic vascular flow on Doppler D) Uniformly anechoic area without internal echoes Answer: C Explanation: Choroidal hemangiomas are moderately echogenic, dome‑shaped, and show internal flow on color Doppler. Question 33. Which artifact is most likely to be produced when the ultrasound beam passes through a highly reflective interface and then re‑enters the same medium? A) Mirror image artifact B) Side‑lobe artifact C) Reverberation artifact D) Comet‑tail artifact Answer: C Explanation: Reverberation occurs when echoes bounce back and forth between two strong reflectors, creating equally spaced lines. Question 34. The primary reason for using a “contact” A‑scan technique rather than immersion in a routine clinic is: A) Higher accuracy of axial length measurement
Sonographer CDOS Exam Guide | Exam Focused
MCQs (2026)
B) Faster acquisition time and convenience C) Ability to image deep orbital structures D) Reduced risk of corneal abrasion Answer: B Explanation: Contact A‑scan is quicker and more convenient, though it may introduce minor corneal compression errors. Question 35. In a patient with proliferative vitreoretinopathy (PVR), B‑scan typically demonstrates: A) Uniformly anechoic vitreous cavity B) Multiple mobile, highly reflective membranes attached to the retina C) A single, thick, immobile retinal detachment membrane only D) Posterior acoustic shadowing without membranes Answer: B Explanation: PVR produces fibrous membranes that are echogenic, may be mobile, and can be attached at various retinal sites. Question 36. Which of the following best describes the purpose of “gain” control on an ultrasound machine? A) To alter the frequency of the emitted sound wave B) To uniformly amplify all returning echoes C) To adjust the focal zone depth D) To switch between A‑scan and B‑scan modes Answer: B
Sonographer CDOS Exam Guide | Exam Focused
MCQs (2026)
B) Vitreous hemorrhage C) Retinal detachment D) Vitreous cavity filled with liquefied vitreous (vitreous liquefaction) Answer: D Explanation: Liquefied vitreous appears anechoic or low‑reflective, similar to fluid. Question 40. In the context of optic nerve sheath diameter measurement, an increased sheath diameter on ultrasound suggests: A) Optic neuritis B) Elevated intracranial pressure (papilledema) C) Optic disc drusen D) Normal variation Answer: B Explanation: The optic nerve sheath expands in response to raised intracranial pressure, measurable with ultrasound. Question 41. Which of the following statements about the “piezoelectric effect” in ultrasound transducers is true? A) Mechanical pressure on the crystal produces an electrical signal only B) An applied electric field causes the crystal to vibrate, generating sound waves C) The effect is only present in magnetic transducers D) It limits the maximum frequency to 5 MHz Answer: B Explanation: Applying an electric voltage to a piezoelectric crystal causes it to deform and emit ultrasonic waves.
Sonographer CDOS Exam Guide | Exam Focused
MCQs (2026)
Question 42. The “axial length” of the eye is measured from: A) Anterior corneal surface to the posterior scleral surface B) Anterior corneal vertex to the retinal pigment epithelium C) Lens anterior capsule to the optic nerve head D) Iris plane to the macula Answer: B Explanation: Axial length is defined from the corneal vertex (or anterior surface) to the retinal pigment epithelium (RPE). Question 43. Which of the following is the most appropriate method to reduce acoustic attenuation when imaging deep posterior segment structures? A) Increase the transducer frequency to >30 MHz B) Decrease the gain setting C) Use a lower frequency transducer (e.g., 10 MHz) D) Apply more coupling gel Answer: C Explanation: Lower frequencies experience less attenuation, allowing deeper penetration at the cost of some resolution. Question 44. In a patient with a suspected choroidal rupture, B‑scan will most likely demonstrate: A) A hyper‑reflective linear discontinuity of the choroid with associated shadowing B) A uniform anechoic area in the vitreous cavity C) A dome‑shaped, highly reflective mass
Sonographer CDOS Exam Guide | Exam Focused
MCQs (2026)
A) Real‑time observation of moving structures such as retinal membranes B) Altering the frequency during a single scan C) Switching between A‑scan and B‑scan automatically D) Using contrast agents to enhance echoes Answer: A Explanation: Dynamic scanning captures motion of intra‑ocular structures, helping differentiate attached vs. mobile lesions. Question 48. Which of the following is NOT a typical indication for using Ultrasound Biomicroscopy (UBM)? A) Evaluation of anterior chamber angle anatomy B) Imaging of posterior vitreous detachment C) Assessment of ciliary body tumors D) Measurement of corneal thickness Answer: B Explanation: UBM is high‑frequency (≥ 50 MHz) and focuses on the anterior segment; it does not image posterior vitreous structures. Question 49. The “acoustic impedance” of a tissue is determined by: A) Its density only B) Its speed of sound only C) The product of its density and speed of sound D) The square of its attenuation coefficient Answer: C
Sonographer CDOS Exam Guide | Exam Focused
MCQs (2026)
Explanation: Acoustic impedance Z = density × speed of sound; differences between tissues cause reflections. Question 50. When evaluating a suspected retinal tear, which B‑scan feature is most diagnostic? A) A stationary, thick, highly reflective membrane attached at both ends B) A focal, thin, highly reflective linear defect with one free edge C) Diffuse low‑level echogenicity throughout the vitreous D) A large, anechoic cavity within the retina Answer: B Explanation: Retinal tears appear as a thin, linear echogenic defect with a free edge that may flutter with eye movement. Question 51. Which ultrasound setting is most important to adjust when imaging a highly myopic eye with an axial length >26 mm? A) Increase the transducer frequency to 30 MHz B) Decrease the focal zone depth to the anterior segment C) Increase the depth range and set the focal zone deeper to reach the retina D) Turn off TGC to avoid over‑amplification Answer: C Explanation: Myopic eyes require deeper imaging; setting a deeper focal zone ensures adequate resolution at the posterior retina. Question 52. The presence of “hyperechoic spikes” on an A‑scan trace within the vitreous chamber most likely indicates: A) Vitreous hemorrhage
