COT Pupil Assessment 4 — Questions and Answers
Question 1: During a slit-lamp examination, you notice the patient's corneal light reflex is displaced nasally. Which condition does this finding most likely indicate?
- Exotropia
- Esotropia (Correct answer)
- Hypertropia
- Hypotropia
Correct answer: Esotropia
A nasally displaced corneal light reflex (Hirschberg test) indicates that the eye is turned outward (the light falls on the nasal cornea when the eye deviates laterally), which corresponds to esotropia — an inward deviation. The reflex displacement is opposite to the direction of the deviation.
Question 2: A 7-year-old child presents with reduced vision in one eye. The cover-uncover test reveals no movement of either eye when covered or uncovered. What does this most likely indicate?
- Alternating esotropia
- Amblyopia without strabismus (Correct answer)
- Intermittent exotropia
- Manifest tropia with fixation preference
Correct answer: Amblyopia without strabismus
If there is no movement on the cover-uncover test, there is no manifest strabismus (tropia). Amblyopia can exist without strabismus — it may be caused by anisometropia or stimulus deprivation. The absence of eye movement on testing rules out a manifest deviation.
Question 3: When performing retinoscopy on a non-verbal toddler, which technique is most appropriate for controlling accommodation?
- Cycloplegic drops before retinoscopy (Correct answer)
- Using a accommodative target at 6 meters
- Asking the child to look at the light
- Performing retinoscopy at near distance only
Correct answer: Cycloplegic drops before retinoscopy
Cycloplegic drops (such as cyclopentolate or atropine) are essential for retinoscopy in young children because they cannot reliably control their accommodation on command. Cycloplegia relaxes accommodation to reveal the true refractive error, particularly important in detecting hyperopia.
Question 4: A patient is asked to follow a penlight in the six cardinal positions of gaze. In left gaze, the right eye shows limited adduction and the left eye shows nystagmoid movements. Which cranial nerve or structure is most likely affected?
- Right CN VI
- Left CN III
- Right medial longitudinal fasciculus (MLF) (Correct answer)
- Left CN VI
Correct answer: Right medial longitudinal fasciculus (MLF)
Internuclear ophthalmoplegia (INO) is caused by a lesion in the medial longitudinal fasciculus (MLF). A right MLF lesion impairs adduction of the right eye in left gaze, while the contralateral (left) eye shows abducting nystagmus. The MLF connects the CN VI nucleus to the contralateral CN III nucleus.
Question 5: During visual acuity testing, a 5-year-old correctly identifies 4 out of 5 optotypes on the 20/32 line but fails on the 20/25 line. How should this result be recorded?
- 20/25
- 20/32 -1
- 20/32 (Correct answer)
- 20/25 +4
Correct answer: 20/32
Visual acuity is recorded as the last line on which the patient correctly identifies the majority of optotypes (at least 3 out of 5 or 4 out of 5 depending on chart type). Since the child correctly identified 4/5 on 20/32 but failed 20/25, the recorded acuity is 20/32. The '-1' notation is optional but the base line is 20/32.
Question 6: You are assessing a patient for relative afferent pupillary defect (RAPD) using the swinging flashlight test. Which finding confirms a positive RAPD in the left eye?
- Both pupils constrict equally when light is shone in either eye
- The left pupil dilates when the light is swung from the right eye to the left eye (Correct answer)
- The right pupil dilates when the light is swung from the right eye to the left eye
- The left pupil constricts briskly when illuminated directly
Correct answer: The left pupil dilates when the light is swung from the right eye to the left eye
A positive RAPD in the left eye is confirmed when the left pupil paradoxically dilates (rather than constricts or maintains constriction) as the light is moved from the unaffected right eye to the affected left eye. This occurs because the afferent signal from the left eye is weaker, so both pupils dilate relative to the stronger stimulus from the right eye.
COT Pupil Assessment 4
During a slit-lamp examination, you notice the patient's corneal light reflex is displaced nasally.
Which condition does this finding most likely indicate?