CO Neuro-Ophthalmic Disorders & Visual Function Testing

Question 1

Which cranial nerve is affected in third nerve palsy?

Accepted Answer

Oculomotor nerve (III)

Answer

The oculomotor nerve (cranial nerve III) innervates most of the extraocular muscles (medial rectus, superior rectus, inferior rectus, inferior oblique) and the levator palpebrae superioris muscle (which lifts the eyelid). Therefore, a third nerve palsy affects multiple eye movements, causing the eye to be down and out, and often results in ptosis (drooping eyelid) and a dilated pupil.

Question 2

Which test is most appropriate for evaluating visual field defects?

Accepted Answer

Perimetry

Answer

Perimetry, also known as visual field testing, specifically maps out the entire area of vision, including central and peripheral fields. It is designed to detect and quantify areas of vision loss or blind spots (scotomas) that indicate damage to the visual pathway, making it the most appropriate test for evaluating visual field defects.

Question 3

A patient presents with bitemporal hemianopia. Where is the lesion most likely located?

Accepted Answer

Optic chiasm

Answer

Bitemporal hemianopia is a visual field defect characterized by loss of vision in the outer (temporal) half of both visual fields. This specific pattern of vision loss occurs when there is damage to the optic chiasm, where the nasal (temporal visual field) fibers from both optic nerves cross. A lesion here interrupts the transmission of information from the temporal visual fields of both eyes.

Question 4

Which of the following is a hallmark sign of Horner’s syndrome?

Accepted Answer

Ptosis and miosis

Answer

Horner's syndrome results from damage to the sympathetic nerve supply to the eye and face. The classic triad of symptoms includes partial ptosis (drooping of the upper eyelid), miosis (constricted pupil), and anhidrosis (decreased sweating on the affected side of the face). Ptosis and miosis are the most consistently observed and defining ocular signs.

Question 5

What is the function of the swinging flashlight test?

Accepted Answer

Identify RAPD

Answer

The swinging flashlight test is used to detect a Relative Afferent Pupillary Defect (RAPD), also known as a Marcus Gunn pupil. An RAPD indicates asymmetric damage to the afferent (sensory) visual pathway, typically in the optic nerve, where one optic nerve transmits less light signal than the other. This test helps localize the side of optic nerve dysfunction.

(CO) Certified Orthoptist Practice Test

(CO) Certified Orthoptist Practice Test

CO Neuro-Ophthalmic Disorders & Visual Function Testing