AOC AOC Diagnostic Testing and Instrumentation 2 — Questions and Answers
Question 1: Optical coherence tomography (OCT) in the context of neuro-ophthalmic care is most useful for assessing which structure?
- Corneal topography
- Retinal nerve fiber layer thickness and optic disc (Correct answer)
- Tear film stability
- Crystalline lens density
Correct answer: Retinal nerve fiber layer thickness and optic disc
OCT measures retinal nerve fiber layer (RNFL) thickness and optic disc morphology, aiding in the diagnosis of glaucoma and optic neuropathies.
Question 2: Forced duction testing during an eye examination is performed to distinguish which two conditions?
- Myopia vs. hyperopia
- Mechanical restriction vs. neurogenic paresis of extraocular motility (Correct answer)
- Amblyopia vs. normal acuity
- Convergence insufficiency vs. divergence excess
Correct answer: Mechanical restriction vs. neurogenic paresis of extraocular motility
Forced duction testing physically moves the eye with instruments; resistance indicates mechanical restriction, while easy movement suggests neurogenic paresis.
Question 3: Which instrument measures the degree of prism-induced deviation needed to neutralize strabismus, forming the basis of the prism cover test?
- Phoropter
- Prism bar or loose prism set (Correct answer)
- Retinoscope
- Keratometer
Correct answer: Prism bar or loose prism set
A prism bar or loose prisms are held before the eye during the cover test; the neutralizing prism power equals the angle of deviation in prism diopters.
Question 4: In the Hess screen test, a contracted field pattern on the affected side indicates which finding?
- Overacting muscle ipsilateral to the small field
- Underacting muscle ipsilateral to the small field (Correct answer)
- Normal ocular motility bilaterally
- Bilateral symmetric palsy
Correct answer: Underacting muscle ipsilateral to the small field
A small (contracted) field on the Hess screen indicates underaction of the muscles on that side, corresponding to a paresis or restriction.
Question 5: Electro-oculography (EOG) measures which physiological parameter of the eye?
- Retinal ganglion cell action potentials
- Standing potential of the eye (retinal pigment epithelium function) (Correct answer)
- Intraocular pressure fluctuations
- Tear film pH
Correct answer: Standing potential of the eye (retinal pigment epithelium function)
EOG records the standing electrical potential between the cornea and retina, reflecting retinal pigment epithelium (RPE) function.
Question 6: A cycloplegic refraction differs from a standard refraction in that it involves which additional step?
- Using a slit lamp instead of a phoropter
- Instilling cycloplegic drops to paralyze accommodation before measuring refractive error (Correct answer)
- Dilating the pupil for fundus imaging only
- Measuring corneal curvature with a keratometer
Correct answer: Instilling cycloplegic drops to paralyze accommodation before measuring refractive error
Cycloplegia (achieved with drops such as cyclopentolate) relaxes accommodation, allowing accurate measurement of the full refractive error, especially in children.
AOC AOC Diagnostic Testing and Instrumentation 2
Optical coherence tomography (OCT) in the context of neuro-ophthalmic care is most useful for assessing which structure?