COT Pupil Assessment 2

Question 1

When performing a confrontation visual field test, a patient fails to see the examiner's finger in the inferior nasal quadrant of the right eye. Which cranial nerve or structure is most likely affected?

Accepted Answer

Right optic nerve

Answer

A monocular field defect affecting only one eye points to pathology anterior to the optic chiasm — specifically the right optic nerve. Chiasmal or post-chiasmal lesions produce binocular (bilateral) field defects.

Question 2

A 7-year-old child exhibits a constant left esotropia of 30 prism diopters with no fixation preference. Best corrected visual acuity is 20/20 OD and 20/80 OS. Which test is most appropriate to quantify the depth of suppression in the amblyopic eye?

Accepted Answer

Neutral density filter bar

Answer

The neutral density filter bar progressively reduces luminance over the fixating eye to measure how deep suppression is in the amblyopic eye. Worth 4-dot and Bagolini lenses detect the presence of suppression but do not quantify depth. Hirschberg estimates the angle of deviation, not suppression depth.

Question 3

During cover-uncover testing of a patient, you observe that the uncovered left eye moves outward when the cover is placed over the right eye. What does this finding indicate?

Accepted Answer

Left esotropia

Answer

In the cover-uncover test, movement of the uncovered eye reveals a manifest tropia. The left eye moving outward (temporally) to pick up fixation means it was previously deviated inward (esotropia). This is a left esotropia — a constant, manifest inward deviation of the left eye.

Question 4

A patient has a best corrected visual acuity of 20/400 in one eye. According to standard clinical definitions, this level of vision corresponds to which category?

Accepted Answer

Legal blindness

Answer

Legal blindness is defined as best corrected visual acuity of 20/200 or worse in the better eye, or a visual field of 20 degrees or less. At 20/400, this patient meets the threshold for legal blindness. Low vision typically refers to 20/70 to 20/200. Total blindness implies no light perception.

Question 5

When using the Hirschberg corneal light reflex test, the examiner notes the reflex is displaced 2 mm temporally in the left eye relative to the right. Approximately how many prism diopters of deviation does this represent, and in which direction?

Accepted Answer

15 prism diopters of esotropia

Answer

Each 1 mm of corneal light reflex displacement corresponds to approximately 7–7.5 prism diopters of deviation. A temporal displacement of the reflex in the left eye means the eye is deviated nasally — an esotropia. At 2 mm, this equals roughly 14–15 prism diopters of esotropia.

COT - Certified Ophthalmic Technician Practice Test

COT - Certified Ophthalmic Technician Practice Test

COT Pupil Assessment 2