COT Pupil Assessment 5 — Questions and Answers
Question 1: During a cover test, a patient's left eye moves outward when the right eye is covered. What does this finding indicate?
- Left esotropia
- Left exotropia (Correct answer)
- Right esotropia
- Right exotropia
Correct answer: Left exotropia
When the left eye moves outward (temporally) upon covering the right eye, it means the left eye was previously deviated inward (esotropia). Wait — actually the eye moves outward to take up fixation, meaning it was turned inward. However, if the uncovered left eye moves OUTWARD to fixate, the left eye was esotropic. But here the movement described is outward, indicating the left eye was in an eso-deviated position. Re-examining: if the left eye moves outward when the right is covered, the left eye was turned inward (esotropia) and moves out to fixate. The correct answer is left esotropia.
Question 2: A 7-year-old child has best-corrected visual acuity of 20/80 in the right eye and 20/20 in the left eye with no structural cause found. Which treatment is most appropriate?
- Prescribe bifocals for the right eye
- Patch the better-seeing left eye to stimulate the amblyopic right eye (Correct answer)
- Patch the right eye to rest it
- Refer immediately for strabismus surgery
Correct answer: Patch the better-seeing left eye to stimulate the amblyopic right eye
Amblyopia (lazy eye) with no structural cause is treated by patching the better-seeing eye (left eye) to force the brain to use the amblyopic right eye. This stimulates visual development in the weaker eye during the critical period of visual development.
Question 3: Which pupillary reflex test is used to identify a relative afferent pupillary defect (RAPD)?
- Consensual light reflex test
- Swinging flashlight test (Correct answer)
- Near reflex test
- Accommodation reflex test
Correct answer: Swinging flashlight test
The swinging flashlight test (also called the Marcus Gunn test) is used to detect a relative afferent pupillary defect (RAPD). The examiner alternately shines a light in each eye; if the pupil dilates instead of constricting when light is moved to one eye, that eye has a reduced afferent input, indicating an RAPD.
Question 4: When assessing near visual acuity in a presbyopic patient, what standard working distance is typically used?
- 20 cm (8 inches)
- 33 cm (13 inches) (Correct answer)
- 50 cm (20 inches)
- 60 cm (24 inches)
Correct answer: 33 cm (13 inches)
Near visual acuity is standardly assessed at 33 cm (approximately 13 inches or 40 cm in some systems), which represents the typical reading distance. This corresponds to a vergence demand of approximately 3 diopters and is the internationally accepted standard for near vision testing.
Question 5: A patient demonstrates a positive Hirschberg test with the corneal light reflex displaced 2 mm nasally in the left eye. What does this indicate?
- Left esotropia of approximately 45 prism diopters
- Left exotropia of approximately 45 prism diopters (Correct answer)
- Left hypertropia of approximately 15 prism diopters
- Normal alignment within physiologic limits
Correct answer: Left exotropia of approximately 45 prism diopters
In the Hirschberg test, each millimeter of corneal reflex displacement corresponds to approximately 22 prism diopters of deviation. A nasal displacement of the reflex in the left eye means the eye is turned outward (exotropia). At 2 mm nasal displacement, this equates to approximately 45 prism diopters of left exotropia.
Question 6: During assessment of a pediatric patient's color vision, you use the Ishihara plates and the child correctly identifies only 4 out of 17 plates. What is the most appropriate next step?
- Document as normal color vision since the child identified some plates
- Diagnose red-green color deficiency and refer to a genetic counselor
- Confirm with an additional color vision test such as the Farnsworth D-15 and document findings (Correct answer)
- Immediately prescribe tinted lenses to correct the deficiency
Correct answer: Confirm with an additional color vision test such as the Farnsworth D-15 and document findings
Identifying fewer than 7 of the Ishihara plates suggests color vision deficiency, but a confirmatory test such as the Farnsworth D-15 or Farnsworth-Munsell 100 hue test should be performed to characterize the type and severity of the deficiency. Proper documentation is essential. Tinted lenses do not correct inherited color vision deficiencies, and genetic counseling is not an immediate next step.
COT Pupil Assessment 5
During a cover test, a patient's left eye moves outward when the right eye is covered.
What does this finding indicate?