Neuro-Ophthalmology Practice Questions

Q: Bitemporal hemianopic field defect is characteristic of:

Pituitary tumour. **Explanation:** The characteristic visual field defect in a **pituitary tumour** is **bitemporal hemianopia**. This occurs because the pituitary gland lies directly beneath the **optic chiasm**. As a pituitary adenoma grows upward (suprasellar extension), it compresses the decussating (crossing) nasal retinal fibers from both eyes. Since the nasal retina is responsible for the temporal visual field, its destruction results in a loss of the outer half of the field of vision in both eyes. **Analysis of Incorrect Options:** * **Glaucoma:** Typically presents with arcuate scotomas, nasal steps, or generalized constriction of the field (tubular vision), rather than hemianopia. * **Optic Neuritis:** Usually presents with a **central or centrocecal scotoma** and is associated with painful eye movements and sudden vision loss, typically unilateral. * **Retinal Detachment:** Causes a field defect that corresponds to the area of detachment (e.g., a superior detachment causes an inferior field defect). It is usually unilateral and preceded by flashes (photopsia) and floaters. **High-Yield Clinical Pearls for NEET-PG:** * **Lesion Site:** Bitemporal hemianopia always localizes the lesion to the **optic chiasm**. * **Superior vs. Inferior:** Compression from *below* (Pituitary Adenoma) causes **upper** bitemporal quadrantanopia first. Compression from *above* (Craniopharyngioma) causes **lower** bitemporal quadrantanopia first. * **Foster Kennedy Syndrome:** Associated with frontal lobe tumours; features ipsilateral optic atrophy and contralateral papilledema. * **Homonymous Hemianopia:** Indicates a post-chiasmal lesion (Optic tract, LGN, or Optic radiations).

Q: In optic atrophy, pallor of the optic disc is an index of:

Loss of vasculature. **Explanation:** The characteristic white or pale appearance of the optic disc in optic atrophy is primarily a clinical observation rather than a direct visualization of dead axons. **Why "Loss of Vasculature" is correct:** The normal pinkish hue of the optic disc is derived from the **capillary network** (specifically the prelaminar capillaries from the circle of Zinn-Haller) that supplies the nerve fiber layer. In optic atrophy, as the nerve fibers degenerate, there is a secondary **obliteration and reduction in the number of these small vessels**. The loss of this microvasculature allows the underlying white lamina cribrosa to become more visible, leading to the clinical sign of "pallor." Therefore, pallor is an index of the **vascularity** of the disc, not the nerve fibers themselves. **Analysis of Incorrect Options:** * **Atrophy of nerve fibers:** While nerve fiber loss is the *cause* of optic atrophy, the fibers themselves are translucent. Their disappearance does not create "whiteness"; rather, it is the loss of the overlying capillaries that causes the change in color. * **Gliosis:** Gliosis (proliferation of astrocytes) often occurs in secondary optic atrophy. While it can contribute to the fuzzy appearance of the disc margins, it is not the primary determinant of the "pallor" index. In some cases (like primary optic atrophy), gliosis is minimal, yet pallor is profound. **High-Yield Clinical Pearls for NEET-PG:** * **Kestenbaum’s Capillary Count:** A clinical method to quantify pallor. Normally, there are about 10 capillaries on the disc surface; a count of less than 6 indicates atrophy. * **Primary Optic Atrophy:** Chalky white disc with clear margins (e.g., Pituitary tumor, MS). * **Secondary Optic Atrophy:** Dirty grey disc with blurred margins due to organized exudates/gliosis (e.g., Post-papilledema). * **Consecutive Optic Atrophy:** Waxy yellow disc (e.g., Retinitis Pigmentosa).

Q: Which extraocular muscle is most commonly affected in raised intracranial pressure?

Lateral rectus. **Explanation:** The **Lateral Rectus** is the correct answer because it is supplied by the **Abducens nerve (CN VI)**, which is the most common cranial nerve to be involved in cases of raised intracranial pressure (ICP). **Why the Lateral Rectus?** The Abducens nerve has the **longest intracranial course** of all cranial nerves. As it emerges from the pontomedullary junction, it travels upwards along the clivus and makes a sharp turn over the petrous part of the temporal bone to enter the cavernous sinus. When ICP increases, the brainstem is displaced downward, causing the nerve to be stretched or compressed against the petrous ligament (Gruber’s ligament). This vulnerability makes CN VI palsy a **"false localizing sign,"** meaning the weakness of the lateral rectus indicates raised ICP rather than a lesion at the nerve's anatomical origin. **Why other options are incorrect:** * **Superior Oblique (A):** Supplied by the Trochlear nerve (CN IV). While CN IV has the longest *subarachnoid* course and is the only nerve to exit posteriorly, it is less susceptible to generalized pressure changes compared to CN VI. * **Inferior Oblique (C) and Inferior Rectus (D):** These are supplied by the Oculomotor nerve (CN III). While CN III can be affected by raised ICP (e.g., uncal herniation leading to a fixed dilated pupil), the lateral rectus is statistically the most frequently involved muscle in generalized intracranial hypertension. **High-Yield Clinical Pearls for NEET-PG:** * **Clinical Presentation:** Patients present with **horizontal diplopia** that worsens on distance gaze and abduction deficiency. * **False Localizing Sign:** Always associate CN VI palsy with raised ICP (e.g., Idiopathic Intracranial Hypertension or brain tumors). * **Gradenigo’s Syndrome:** Triad of Abducens palsy, suppurative otitis media, and trigeminal pain (due to petrous apicitis).

Q: Schirmer's test is done to assess the function of which of the following cranial nerves?

Facial nerve. **Explanation:** The **Schirmer’s test** is used to measure tear production and assess for aqueous tear deficiency (e.g., in Sjögren’s syndrome). The correct answer is the **Facial nerve (CN VII)** because it carries the **parasympathetic secretomotor fibers** responsible for lacrimation. **Why Facial Nerve is Correct:** The pathway for lacrimation begins in the lacrimatory nucleus (pons). The fibers travel via the **nervus intermedius**, then the **greater petrosal nerve** (a branch of CN VII), and eventually synapse at the pterygopalatine ganglion. Postganglionic fibers then reach the lacrimal gland via the zygomatic and lacrimal nerves. Therefore, a lesion of the facial nerve proximal to the geniculate ganglion results in a dry eye, which can be detected by a Schirmer’s test. **Why Other Options are Incorrect:** * **Optic nerve (CN II):** This is a purely sensory nerve responsible for vision and the afferent limb of the pupillary light reflex; it has no role in tear production. * **Oculomotor nerve (CN III):** This nerve controls most extraocular muscles, levator palpebrae superioris, and provides parasympathetic supply to the ciliary muscle and sphincter pupillae (for accommodation and miosis), but not the lacrimal gland. **Clinical Pearls for NEET-PG:** * **Schirmer’s I:** Measures total secretion (reflex + basal). Normal is >15 mm in 5 minutes. <5 mm is diagnostic of dry eye. * **Schirmer’s II:** Measures basal secretion only (performed after applying topical anesthesia to eliminate reflex tearing). * **Topographic Diagnosis:** In cases of Bell’s Palsy, a reduced Schirmer’s test indicates the lesion is at or proximal to the **geniculate ganglion**.

Q: Which of the following is NOT a feature of oculomotor nerve palsy?

Miosis. **Explanation:** The **Oculomotor nerve (CN III)** carries both motor (somatic efferent) and parasympathetic (visceral efferent) fibers. It supplies four extraocular muscles (Superior Rectus, Inferior Rectus, Medial Rectus, and Inferior Oblique), the Levator Palpebrae Superioris (LPS), and the constrictor pupillae. **Why Miosis is the correct answer:** Miosis (pupillary constriction) is mediated by **parasympathetic fibers** originating from the **Edinger-Westphal nucleus**. In CN III palsy, these fibers are paralyzed, leading to the loss of constrictor tone. This results in **Mydriasis** (a dilated pupil) due to the unopposed action of the sympathetic system, not miosis. **Analysis of Incorrect Options:** * **Difficulty in accommodation:** The parasympathetic fibers of CN III also supply the **ciliary muscle**. Paralysis leads to loss of accommodation, making it a classic feature. * **Superior gaze palsy:** CN III supplies the **Superior Rectus** and **Inferior Oblique**, both of which are responsible for upward gaze. Their paralysis leads to an inability to look up. * **Diplopia:** Due to the paralysis of multiple extraocular muscles, the eyes become misaligned (typically resulting in a "down and out" position). This misalignment causes double vision (diplopia). **High-Yield Clinical Pearls for NEET-PG:** 1. **The "Down and Out" Eye:** The classic position in CN III palsy because the Lateral Rectus (CN VI) and Superior Oblique (CN IV) are still functioning. 2. **Ptosis:** Occurs due to paralysis of the LPS muscle. 3. **Medical vs. Surgical Third Nerve Palsy:** * **Medical (e.g., Diabetes/HTN):** Pupil is usually **spared** because the parasympathetic fibers are located peripherally and have a different blood supply (vasa nervorum). * **Surgical (e.g., PCom Artery Aneurysm):** Pupil is **involved** (dilated) because external compression hits the superficial parasympathetic fibers first.

Q: Most isolated trochlear nerve palsies are due to which of the following?

Closed head injuries. **Explanation:** The **Trochlear Nerve (CN IV)** is unique among cranial nerves: it has the longest intracranial course (approx. 75mm), the thinnest caliber, and is the only nerve to exit from the dorsal aspect of the brainstem. These anatomical factors make it exceptionally vulnerable to **shearing forces** during trauma. **1. Why Closed Head Injury is correct:** Trauma is the most common cause of acquired isolated trochlear nerve palsy. Even minor, non-penetrating head injuries (where there is no loss of consciousness) can cause the nerve to impact the rigid tentorial edge or suffer avulsion at the exit point from the dorsal midbrain. **2. Analysis of Incorrect Options:** * **Idiopathic causes:** While common in some series, trauma remains the leading identifiable cause in clinical practice and standard textbooks (like Kanski). * **Aneurysmal rupture:** This is a classic cause for **Third Nerve (Oculomotor) palsy**, specifically involving the Posterior Communicating Artery. It rarely affects the isolated Fourth nerve. * **Diabetes mellitus:** Microvascular ischemia (Diabetes/Hypertension) is the leading cause of isolated **Sixth Nerve (Abducens)** and pupil-sparing Third Nerve palsies, but it is less common than trauma for the Fourth nerve. **Clinical Pearls for NEET-PG:** * **Clinical Presentation:** Patients present with **vertical diplopia** (worse on downgaze and adduction) and a compensatory **contralateral head tilt** (Bielschowsky head tilt test) to minimize the double vision. * **Action of SO:** The Superior Oblique primarily **intorts**, depresses, and abducts the eye. * **Congenital vs. Acquired:** Congenital Fourth nerve palsy is also common; look for a history of old photographs showing a head tilt or large vertical fusional amplitudes.

Question 1

Acute papilloedema typically presents with which of the following findings?

Accepted Answer

Sudden loss of vision

Answer

Post-neuritic atrophy

Answer

Enlarged blind spot

Answer

Hyperemic disc

Question 2

Bitemporal hemianopic field defect is characteristic of:

Accepted Answer

Pituitary tumour

Answer

Glaucoma

Answer

Optic neuritis

Answer

Retinal detachment

Question 3

In optic atrophy, pallor of the optic disc is an index of:

Accepted Answer

Loss of vasculature

Answer

Atrophy of the nerve fibre

Answer

Gliosis

Answer

All of the above

Question 4

Which extraocular muscle is most commonly affected in raised intracranial pressure?

Accepted Answer

Lateral rectus

Answer

Superior oblique

Answer

Inferior oblique

Answer

Inferior rectus

Question 5

Schirmer's test is done to assess the function of which of the following cranial nerves?

Accepted Answer

Facial nerve

Answer

Oculomotor nerve

Answer

Optic nerve

Answer

None of the above

Question 6

Superior oblique palsy testing is performed by checking for its action of intorsion while asking the subject to look in which direction?

Accepted Answer

Down and in

Answer

Straight down

Answer

Straight up

Answer

Down and out

Question 7

Which of the following is NOT a feature of oculomotor nerve palsy?

Accepted Answer

Miosis

Answer

Difficulty in accommodation

Answer

Superior gaze palsy

Answer

Diplopia

Question 8

Incongruous contralateral hemianopia is seen in which type of lesion?

Accepted Answer

Lateral geniculate nucleus lesion

Answer

Optic tract lesion

Answer

Optic chiasma lesion

Answer

Medial geniculate nucleus lesion

Question 9

Most isolated trochlear nerve palsies are due to which of the following?

Accepted Answer

Closed head injuries

Answer

Idiopathic causes

Answer

Aneurysmal rupture

Answer

Diabetes mellitus

Question 10

Which of the following is a cause of sudden blindness in a quiet eye with normal media and fundus?

Accepted Answer

Acute retrobulbar neuritis

Answer

Vitreous hemorrhage

Answer

Iridocyclitis

Answer

All of the above

Neuro-Ophthalmology — MCQs

Neuro-Ophthalmology — MCQs

On this page

Practice by Chapter

Want unlimited practice?