JCAHPO Patient Evaluation 4 — Questions and Answers
Question 1: When using a non-contact tonometer (air-puff), the IOP reading is derived from:
- The color of the reflected corneal reflex
- The time required for the air pulse to applanate the cornea (Correct answer)
- The width of the fluorescein mire
- The resistance of the sclera to indentation
Correct answer: The time required for the air pulse to applanate the cornea
The non-contact tonometer measures the time from air-puff initiation to corneal applanation; a shorter time indicates higher IOP.
Question 2: A patient describes sudden painless loss of vision in one eye 'like a curtain coming down.' This presentation is most consistent with:
- Central retinal artery occlusion
- Rhegmatogenous retinal detachment (Correct answer)
- Optic neuritis
- Acute angle-closure glaucoma
Correct answer: Rhegmatogenous retinal detachment
A spreading shadow or 'curtain' obscuring peripheral vision that progresses centrally is the classic description of rhegmatogenous retinal detachment.
Question 3: When evaluating extraocular motility, which position of gaze isolates the function of the superior oblique muscle in the right eye?
- Right gaze and up
- Left gaze and down (Correct answer)
- Primary position
- Right gaze and down
Correct answer: Left gaze and down
The superior oblique primarily depresses and intorts the eye; its depression function is best isolated in adduction (left gaze for the right eye).
Question 4: Stereoacuity tests such as the Randot or TNO test assess:
- Monocular depth cues
- Binocular disparity-based depth perception (Correct answer)
- Convergence amplitude
- Fusional vergence range
Correct answer: Binocular disparity-based depth perception
Stereoacuity tests measure the ability to perceive depth from binocular retinal disparity, reflecting the quality of binocular fusion.
Question 5: The Schirmer test strip placed at the junction of the middle and lateral third of the lower lid is used to evaluate:
- Corneal sensitivity
- Aqueous tear production (Correct answer)
- Meibomian gland function
- Conjunctival goblet cell density
Correct answer: Aqueous tear production
The Schirmer test measures aqueous tear production by quantifying wetting of the strip in 5 minutes; ≥10 mm is generally normal.
Question 6: A patient with a nuclear sclerotic cataract would most likely experience a myopic shift because:
- The cornea steepens with age
- Increased lens density raises the refractive index (Correct answer)
- The axial length of the eye shortens
- The pupil constricts in bright light
Correct answer: Increased lens density raises the refractive index
Nuclear sclerosis increases the refractive index of the crystalline lens, causing increased convergence of light and a shift toward myopia (second sight).
Question 7: In the four-diopter base-out prism test, movement of both eyes in response to a prism placed before one eye indicates:
- Suppression of that eye
- Presence of bifoveal fusion (Correct answer)
- A large-angle exotropia
- Amblyopia in the tested eye
Correct answer: Presence of bifoveal fusion
Bilateral eye movement (version and then fusional vergence) in response to a 4Δ base-out prism indicates intact bifoveal correspondence and active fusion.
JCAHPO Patient Evaluation 4
When using a non-contact tonometer (air-puff), the IOP reading is derived from: