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ROUB Study Guide Actual Questions and Answers 100% Verified
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ROUB Study Guide Actual Questions and Answers 100% Verified
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ROUB Study Guide 2023-2024 Actual Questions and Answers 100% VerifiedIf your biometry instrument has one pseudophakic eye-type setting, what is the only IOL
material that can accurately be measured? Answer- Polymethyl methacrylate (PMMA)
If a gain setting is increased in order to obtain a 100% tall retina and sclera echo, what type of cataract is being evaluated? Answer- A dense cataract
What transducer frequency is generally used for a biometry A-scan probe? Answer- 10
MHz
What is the velocity of a biometer that only uses an average velocity to measure the entire axial length? Answer- 1550 m/sec
What is one of the most important features of a biometer? Answer- Display screen
What are the velocity settings for a phakic eye? Answer- 1532 m/sec for the aqueous; 1641 m/sec for the lens; and, 1532 m/sec for the vitreous cavity
What should the examiner do to reduce the presence of a reverberation echo created by a dense cataract? Answer- Reduce the gain
What is the term for the electronic calipers that measure the distance between two or more anatomic interfaces? Answer- Gates
Of the following settings on the biometer (gain, gates, A-scan probe frequency, eye type, and screen brightness), which cannot be changed by the examiner? Answer- A-
scan probe frequency
What is the proper sound velocity used to measure the distance between the anterior and posterior lens interfaces in a phakic eye? Answer- 1641 m/sec
When performing immersion biometry, which gate in relation to the initial spike represents the cornea? Answer- Corneal gate is to the right of the initial spike
What is the possible cause for a biometry instrument to indicate an unusually short measurement of a pseudophakic eye with a PMMA implant? Answer- Multiple signal of
the echo with improper identification of the retina
What biometer setting changes the degree of echo amplification? Answer- Gain What is the term for the relative strength or amplitude of an echo displayed on a biometer? Answer- Reflectivity
When measuring an eye that has no crystalline lens, the instrument should be set on which eye type? Answer- Aphakic
What is the term for the "markers" or "cursors" displayed on the screen of a biometry instrument that provide electronic measurements of distance between two or more acoustic interfaces? Answer- Gates
What is the term for the capacity of an ultrasound instrument to display two or more interfaces that are very anatomically close to one another as separate echoes? Answer- Resolution
How does increasing the gain setting on the biometer affect the display echo? Answer-
It increases the amount of amplification of the echo
What is the range of ophthalmic biometry frequencies? Answer- 8-12 MHz
How is the resolution affected when the gain is set at maximum? Answer- The resolution is less
A non-focused sound beam is always utilized by which type of scan? Answer- Diagnostic A-scan
What scan is used to obtain a two-dimensional image of the globe? Answer- Diagnostic B-scan
What is the term for a one-dimensional amplitude scan? Answer- A-scan
The strength of an echo is dependent on what three factors? Answer- Gain, difference in density, and proper alignment
What type of scan uses Prager or scleral shells? Answer- Immersion A-scan
How often should the filter of a biometry instrument be vacuumed? Answer- Once a month
Measurement of axial length of the eye, thickness of an extraocular muscle, and tumor height are all within the definition of what term? Answer- Biometry
What is the leading cause of an unplanned, post-operative refractive error? Answer- An error in the measurement of axial length
An error of 0.1 mm in the axial length measurement can result in a post-operative refraction error of how many diopters? Answer- 0.25D
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