COT Pupil Assessment 1 — Questions and Answers
Question 1: When performing a confrontation visual field test on a patient, which technique best detects peripheral field defects?
- Ask the patient to count fingers presented in each quadrant while covering one eye (Correct answer)
- Use a penlight to check the patient's pupillary response in bright and dim light
- Have the patient read the smallest line on a Snellen chart from 20 feet
- Perform the Hirschberg test by shining a light at the patient's eyes simultaneously
Correct answer: Ask the patient to count fingers presented in each quadrant while covering one eye
Confrontation visual field testing involves asking the patient to cover one eye and count or identify finger movements presented in each quadrant of the visual field. This technique compares the patient's peripheral vision to the examiner's, allowing detection of field defects such as hemianopias or scotomas without specialized equipment.
Question 2: A patient presents with a Marcus Gunn pupil. Which finding would confirm this diagnosis?
- Both pupils constrict normally when light is shone in the unaffected eye, but the affected eye's pupil paradoxically dilates when light is swung to it (Correct answer)
- The affected pupil remains fixed and dilated regardless of light stimulation
- Both pupils dilate simultaneously when any light is introduced to either eye
- The affected pupil constricts more rapidly than the normal pupil during direct light stimulation
Correct answer: Both pupils constrict normally when light is shone in the unaffected eye, but the affected eye's pupil paradoxically dilates when light is swung to it
A Marcus Gunn pupil (relative afferent pupillary defect, RAPD) is identified using the swinging flashlight test. When light is moved from the normal eye to the affected eye, the affected eye's pupil paradoxically dilates instead of maintaining constriction, indicating reduced afferent input on that side due to optic nerve or severe retinal disease.
Question 3: During distance visual acuity testing with a Snellen chart, a patient reads the 20/40 line with the right eye but misses two letters on the 20/20 line. How should this be recorded?
- 20/20 -2 OD (Correct answer)
- 20/40 +2 OD
- 20/20 OD with 2 errors
- 20/40 OD, best corrected
Correct answer: 20/20 -2 OD
Standard notation records the smallest line where the patient correctly identifies the majority of optotypes. If the patient reads the 20/20 line but misses two letters, it is recorded as 20/20 -2 (minus the number of letters missed on that line). This provides a precise record of the patient's performance at that acuity level.
Question 4: Which of the following is the most appropriate method for assessing near visual acuity in an adult patient?
- Present a near acuity card at 14–16 inches and record the smallest print the patient reads accurately (Correct answer)
- Use a Snellen chart at 10 feet and adjust the lighting to simulate near conditions
- Ask the patient to read newspaper print at arm's length without corrective lenses
- Measure the patient's ability to see a penlight at 6 inches in each eye separately
Correct answer: Present a near acuity card at 14–16 inches and record the smallest print the patient reads accurately
Near visual acuity is assessed using a standardized near acuity card (such as the Rosenbaum or Jaeger card) held at the standard reading distance of 14–16 inches (approximately 40 cm). The smallest line the patient can read accurately is recorded along with the testing distance to ensure consistency and comparability across visits.
Question 5: When evaluating extraocular muscle function in a pediatric patient suspected of having strabismus, the cover-uncover test is performed. What does the examiner observe to indicate the presence of a tropia?
- The uncovered eye makes a refixation movement when the fellow eye is covered (Correct answer)
- Both eyes move simultaneously when only one eye is covered
- The covered eye drifts outward while being occluded and returns when uncovered
- The patient reports diplopia only when the cover is removed from the occluded eye
Correct answer: The uncovered eye makes a refixation movement when the fellow eye is covered
In the cover-uncover test, a tropia (manifest deviation) is detected when the uncovered eye makes a refixation movement as the fellow eye is covered. This movement indicates that the uncovered eye was not fixating on the target before the cover was applied, revealing a manifest misalignment. No movement of the uncovered eye suggests no tropia is present.
Question 6: A COT is performing a color vision assessment using Ishihara pseudoisochromatic plates. The patient fails to identify numbers on several plates. Which type of color deficiency is the Ishihara test primarily designed to detect?
- Red-green color deficiency (Correct answer)
- Blue-yellow color deficiency (tritanopia)
- Achromatopsia (total color blindness)
- Unilateral color vision loss from optic neuritis
Correct answer: Red-green color deficiency
The Ishihara pseudoisochromatic plate test is specifically designed and validated to detect red-green color deficiencies, including protanopia (red deficiency) and deuteranopia (green deficiency). It is not reliable for detecting blue-yellow defects (tritanopia) or total color blindness. Acquired unilateral color loss from optic neuritis requires different comparative testing methods.
COT Pupil Assessment 1
When performing a confrontation visual field test on a patient, which technique best detects peripheral field defects?