10 exam-style questions with answers and explanations, straight from our 1,030-question bank. Tap an answer to check yourself. When you're ready, take the scored version in the free practice test.
These 10 free ROUB questions are organized by exam domain, so you can see how each part of the Registered Ophthalmic Ultrasound Biometrist blueprint is tested. Reveal the answer and explanation under each question.
Repeatable keratometry shows a radius of 7.50 mm in the 90-degree meridian and 8.00 mm in the 180-degree meridian. The cornea has regular astigmatism. Using K = 337.5/r, with r in millimeters, the keratometric astigmatism should be recorded as:
Correct answer: D - 2.81 D, with the steep meridian at 90 degrees
An immersion A-scan records echo arrivals 2 microseconds after transmission at the cornea, 6 at the anterior lens surface, 12 at the posterior lens surface, and 36 at the retina. The vitreous sound velocity is 1,532 m/s. Using distance in mm = velocity in m/s x round-trip time in microseconds / 2,000, which interval and result belong to the vitreous chamber?
Correct answer: C - Posterior lens surface to retina: 18.38 mm
During a probe test, two closely spaced reflectors lie one behind the other along the ultrasound beam. Their returns merge into one broad echo even though the beam is sharply focused at that depth. Which change would help resolve the two reflectors?
Correct answer: C - Increase damping to shorten the transmitted pulse.
A patient with a dense cataract cannot obtain a valid axial-length reading on the clinic's optical biometer despite correct positioning and repeated attempts. The ophthalmologist has completed the posterior-segment assessment and requested biometry. A calibrated ultrasound biometer and immersion equipment are available. How should axial length be obtained at this visit?
Correct answer: A - Perform immersion A-scan biometry and inspect the acquired traces.
A well-aligned phakic A-scan has a clearly identifiable posterior lens echo that falls just below the capture threshold. The anterior lens and retinal echoes are already near the top of the display. The biometer provides separate gain controls for each of these three interfaces. The most targeted adjustment is to:
Correct answer: B - Increase posterior-lens gain while leaving the other two gains unchanged.
Before a scheduled contact A-scan, a patient reports that a metal fragment struck the eye that morning. Vision has suddenly worsened, and the pupil appears peaked toward a visible corneal wound. What is the immediate priority?
Correct answer: D - Avoid ocular pressure and obtain immediate ophthalmic assessment.
In an eye with a documented posterior staphyloma, independently repeated immersion scans measure 29.10 mm along the verified foveal path and 30.20 mm when the beam is directed toward the deepest, eccentric part of the staphyloma. Both sets have sharp echoes. Which measurement belongs in the IOL calculation?
Correct answer: A - The 29.10-mm measurement along the verified foveal path
Contact A-scan of a phakic eye gives an axial length of 23.46 mm and an anterior chamber depth of 2.82 mm. Careful immersion measurements give 23.82 mm and 3.18 mm, respectively. Lens thickness and vitreous chamber depth agree. The corneal start and other anatomical interfaces are correctly identified in both sets. What best accounts for the paired change?
Correct answer: B - The contact probe indented the cornea during acquisition.
A phakic eye has a vitreous cavity completely filled with silicone oil. The anterior-cornea-to-lens depth of 3.20 mm and lens thickness of 4.30 mm have been measured correctly. The vitreous segment displays 27.576 mm because it was converted at 1,532 m/s instead of the specified oil velocity of 980 m/s. All interfaces are correctly identified, and no oil correction has been applied. Which corrected axial length is supported by these measurements?
Correct answer: C - 25.14 mm
Years after myopic LASIK, a patient is being evaluated for cataract surgery. Axial length is reliable, but conventional anterior-surface keratometry overestimates the eye's true corneal power. If that uncorrected corneal power is used in an otherwise appropriate calculation for a positive-power IOL, what refractive error does this specific bias tend to produce, and why?
Correct answer: A - Hyperopia, because the calculated IOL power is too low.
The full bank has 1,020 more ROUB questions with explanations.
Continue in the free practice test →
View plans