100+ Free CDOS Practice Questions

Pass your IJCAHPO Certified Diagnostic Ophthalmic Sonographer exam on the first try — instant access, no signup required.

✓ No registration✓ No credit card✓ No hidden fees✓ Start practicing immediately

100+ Questions

100% Free

1 / 100

Question 1

Score: 0/0

What is the role of the standardized A-scan when paired with B-scan for a choroidal mass?

To measure intraocular pressure

To capture color fundus photographs

To replace B-scan entirely

To quantify internal reflectivity and characterize tissue architecture

to track

Same family resources

More IJCAHPO Ophthalmic Certifications Prep

Continue through related practice pages, study guides, comparisons, and articles from the same exam family.

Practice Pages

IJCAHPO CCOA Corporate Certified Ophthalmic Assistant Practice100 questions IJCAHPO Certified Ophthalmic Medical Technologist Practice100 questions IJCAHPO Certified Ophthalmic Technician Practice100 questions IJCAHPO OSA Ophthalmic Surgical Assisting Practice100 questions IJCAHPO OSC Ophthalmic Scribe Certification Practice100 questions IJCAHPO ROUB Registered Ophthalmic Ultrasound Biometrist Practice100 questions

FREE IJCAHPO COT Exam Guide 2026: 200 Questions + 7 Skills15 min read IJCAHPO COA Exam 2026: FREE Certified Ophthalmic Assistant Study Guide & Pathways34 min read

2026 Statistics

Key Facts: CDOS Exam

170

MCQ Items

IJCAHPO CDOS

3 hrs

Exam Time

IJCAHPO

10 MHz

B-scan Probe

Standard ophthalmic frequency

Pearson VUE

Delivery

IJCAHPO

IJCAHPO CDOS is the B-scan ophthalmic sonography credential. 170 MCQ, 3 hours. Master 10 MHz probe technique, axial/longitudinal/transverse orientations, kinetic exam to differentiate RD (attached to disc, taut) from PVD (mobile, doesn't attach), choroidal melanoma (collar-button, low-medium reflectivity, choroidal excavation), and open-globe imaging precautions.

Sample CDOS Practice Questions

Try these sample questions to test your CDOS exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1What is the typical operating frequency of a B-scan ophthalmic ultrasound probe?

A.2 MHz

B.5 MHz

C.10 MHz

D.50 MHz

Explanation: Standard B-scan ophthalmic ultrasound probes operate at approximately 10 MHz (range 10-20 MHz). This high frequency provides excellent resolution for the small ocular structures while penetrating to the posterior orbit.

2What does the probe marker indicate on the B-scan display?

A.The 6 o'clock position on the display

B.The 12 o'clock position on the display

C.The center of the globe

D.The optic nerve location

Explanation: The probe marker corresponds to the 12 o'clock (top) position on the display screen. This orientation cue allows the sonographer to correlate scan plane orientation with the patient's eye anatomy.

3Which scan orientation passes through the visual axis with the probe marker at the 12 o'clock meridian?

A.Transverse scan

B.Longitudinal scan

C.Axial scan

D.Topographic scan

Explanation: An axial scan passes through the visual axis (cornea, lens, vitreous, and optic nerve in one plane) with the probe placed on the cornea or central lid and the marker at 12 o'clock. It produces the classic image showing the optic nerve shadow centrally.

4In a longitudinal scan, where is the probe marker oriented?

A.Toward the limbus

B.Toward the nose

C.Toward the brow

D.Perpendicular to the limbus

Explanation: In a longitudinal scan, the probe is placed at the limbus opposite the area of interest, with the marker oriented toward the limbus. This evaluates a single clock-hour meridian from anterior to posterior in one plane.

5What does a transverse B-scan evaluate?

A.A single clock-hour meridian

B.The visual axis only

C.Equatorial structures across multiple clock hours

D.Only the optic nerve sheath

Explanation: A transverse scan, with the marker oriented nasally or temporally at the limbus, evaluates equatorial structures across multiple clock hours simultaneously. It is useful for surveying large areas of peripheral retina.

6Which of the following best describes a kinetic B-scan examination?

A.A still image series for documentation

B.Real-time scanning while asking the patient to move the eye to assess membrane mobility

C.An A-scan combined with a B-scan in tandem

D.A high-frequency ultrasound biomicroscopy of the angle

Explanation: Kinetic examination involves real-time scanning during eye movement (or during probe motion) so the sonographer can observe how membranes move. Mobility patterns help differentiate retinal detachment, posterior vitreous detachment, and vitreous hemorrhage.

7Why is coupling gel used during a B-scan ophthalmic examination?

A.To anesthetize the eyelid

B.To provide acoustic coupling between the probe and the skin or cornea

C.To sterilize the probe

D.To improve image color

Explanation: Coupling gel eliminates the air gap between the probe and the eyelid (or cornea), enabling sound waves to transmit efficiently. Without acoustic coupling, ultrasound is reflected at the air-skin interface and no usable image is obtained.

8What is the most common method of probe placement during routine B-scan ophthalmic ultrasound?

A.Direct corneal contact without anesthesia

B.Through the closed eyelid using coupling gel

C.Through a water bath only

D.Via transcutaneous orbital approach posteriorly

Explanation: The most common technique is to place the probe on the closed eyelid with coupling gel. This is comfortable for the patient, requires no topical anesthesia, and provides excellent images for the vast majority of indications.

9When direct corneal contact B-scan is performed, what additional preparation is required?

A.Pupil dilation

B.Instillation of topical anesthetic drops

C.Insertion of a scleral lens

D.Systemic sedation

Explanation: Direct corneal contact B-scan requires topical anesthetic drops (e.g., proparacaine) to make placement comfortable and prevent the blink reflex. Sterile coupling solution is also used.

10Which structure forms the outer fibrous coat of the globe?

A.Choroid

B.Sclera

C.Retina

D.Vitreous

Explanation: The sclera is the tough white outer fibrous tunic of the eye, providing structural support and protection. On B-scan it appears as a highly reflective curved shell.

About the CDOS Exam

IJCAHPO specialty credential for diagnostic ophthalmic sonographers — B-scan ultrasound for posterior segment evaluation. 170 MCQ exam covering ocular anatomy, B-scan imaging techniques (axial/longitudinal/transverse, kinetic exam), patient care, pathology interpretation (RD, PVD, vitreous hemorrhage, choroidal melanoma vs hemangioma, retinoblastoma), equipment (10 MHz probe, gain settings), and documentation.

Questions

170 scored questions

Time Limit

3 hours

Passing Score

Scaled (IJCAHPO-set)

Exam Fee

~$350-525 (IJCAHPO via Pearson VUE)

CDOS Exam Content Outline

35%

Pathology Interpretation

RD, PVD, vitreous hemorrhage, choroidal melanoma vs hemangioma, retinoblastoma calcifications, optic nerve drusen, asteroid hyalosis

25%

B-scan Imaging Techniques

Probe orientation (axial/longitudinal/transverse), kinetic exam, gain strategy

15%

Ocular Anatomy

Globe, retina, choroid, vitreous, optic nerve, orbit

10%

Patient Care

Prep, lid technique, contact gel, infection control, open globe precautions

10%

Equipment & Instrumentation

10 MHz probe, gain settings (high for subtle, low for solid), dynamic range, freeze frame

Documentation

Image labeling, report format, communication with MD (sonographer describes; MD interprets)

How to Pass the CDOS Exam

What You Need to Know

Passing score: Scaled (IJCAHPO-set)
Exam length: 170 questions
Time limit: 3 hours
Exam fee: ~$350-525

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

CDOS Study Tips from Top Performers

1Master kinetic exam to differentiate RD (attached to disc, low mobility) from PVD (mobile, doesn't attach)

2Memorize choroidal melanoma B-scan: collar button, MEDIUM-LOW reflectivity, choroidal excavation, shadowing

3Drill probe orientation: axial through visual axis, longitudinal evaluates clock-hour, transverse evaluates equator

4Know gain strategy: HIGH gain (90-100 dB) for subtle (vitreous heme, PVD); LOW gain (50-70 dB) for solid structures

5Apply open-globe precautions: NO direct contact; sterile cover + closed-lid imaging if essential

Frequently Asked Questions

How do you differentiate retinal detachment from posterior vitreous detachment on B-scan?

RD: highly reflective membrane attached to the optic nerve head (NEVER crosses it), low mobility (taut funnel-shape in long-standing), V-shape on axial scan. PVD: mobile membrane, low reflectivity, separated from retina but typically does NOT attach to optic disc, may show Weiss ring (round echo near ON head from peripapillary glial tissue). Use kinetic exam (move probe to assess mobility): RD undulates minimally; PVD swings freely.

What is the classic B-scan appearance of choroidal melanoma?

Choroidal melanoma: dome-shaped or "collar button" / mushroom shape (when Bruch's membrane breaks), MEDIUM-LOW internal reflectivity (vs choroidal hemangioma which is HIGH reflectivity), choroidal excavation (concave depression of underlying choroid), acoustic shadowing, and may show vascular signal on Doppler. Tumor measurements (basal diameter + height) are required for AJCC TNM staging. Differential includes hemangioma (high reflectivity, no shadow, no excavation) and metastasis (irregular, moderate-high reflectivity).

When should B-scan be avoided?

Open globe injury — direct contact with the globe risks extruding intraocular contents. If imaging is essential, use sterile coupling gel, sterile probe cover, lightest possible touch, and image through closed lid only. Most ophthalmologists prefer to defer B-scan until after surgical closure of the globe. Document any open globe finding on order before scanning. Suspected ruptured globe always = no contact imaging.

How should I study for IJCAHPO CDOS?

Plan 80-120 hours over 12-16 weeks. Focus weighted study on Pathology Interpretation (35%) and B-scan Imaging Techniques (25%) — together 60% of exam. Master RD vs PVD distinction (kinetic exam), choroidal melanoma "collar button" + low-medium reflectivity + excavation, and probe orientation conventions. Hands-on B-scan experience with image library review reinforces pattern recognition.