Neuro-Ophthalmology Practice Questions

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.

Q: Blind spot enlargement indicates:

Papilloedema. ### Explanation **Correct Answer: C. Papilloedema** **Mechanism:** The physiological blind spot (Mariotte's spot) corresponds to the **optic nerve head**, where there are no photoreceptors. In **papilloedema** (passive disc swelling due to increased intracranial pressure), the optic disc undergoes edema and expansion. This swelling causes the surrounding peripapillary retina to be pushed away and the sensory retina to be displaced or lifted (Paton’s folds). This physical enlargement of the non-receptive area results in a **centrifugal enlargement of the blind spot** on visual field testing (perimetry). **Why other options are incorrect:** * **Retinal Detachment (A):** Typically presents with a dense scotoma corresponding to the area of detachment or a "curtain-like" loss of vision, rather than isolated blind spot enlargement. * **Avulsion of Optic Nerve (B):** This is a traumatic event leading to immediate, profound vision loss and a total or massive field defect, not a localized enlargement of the blind spot. * **Papillitis (D):** This is primary inflammation of the optic disc (optic neuritis). Unlike papilloedema, the hallmark of papillitis is a **central or centrocecal scotoma** with a significant, early decrease in visual acuity and color vision. **High-Yield Clinical Pearls for NEET-PG:** * **Papilloedema vs. Papillitis:** In early papilloedema, visual acuity is usually **preserved**, whereas in papillitis, visual acuity is **severely diminished**. * **Foster Kennedy Syndrome:** Characterized by optic atrophy in one eye (due to direct compression by a tumor) and papilloedema in the other (due to increased ICP). * **Visual Field in Glaucoma:** Remember that glaucoma causes arcuate scotomas (Bjerrum’s scotoma) and nasal steps, not simple blind spot enlargement. * **Paton’s Lines:** Circumferential retinal folds seen in chronic papilloedema.

Q: Optic atrophy may occur in all of the following conditions, EXCEPT:

Leprosy. **Explanation:** Optic atrophy refers to the degeneration of the retinal ganglion cell axons, resulting in a pale optic disc and loss of visual function. To answer this question, one must distinguish between diseases that affect the **optic nerve** versus those that primarily affect the **anterior segment**. **Why Leprosy is the Correct Answer:** Leprosy (*Mycobacterium leprae*) primarily affects the anterior segment of the eye. Common ocular manifestations include madarosis (loss of eyebrows/lashes), lagophthalmos (due to facial nerve palsy), exposure keratitis, and chronic granulomatous uveitis. It **does not** involve the optic nerve; therefore, it does not cause optic atrophy. **Analysis of Incorrect Options:** * **Glaucoma:** This is a leading cause of **consecutive optic atrophy**. Increased intraocular pressure leads to mechanical and ischemic damage to the optic nerve head, resulting in characteristic "cupping." * **Pituitary Tumor:** Tumors like pituitary adenomas cause **ascending (secondary) optic atrophy** due to direct pressure on the optic chiasm. This typically presents with bitemporal hemianopia. * **Methanol Intake:** Methanol is metabolized into formic acid, which is highly toxic to the optic nerve. It causes acute optic disc edema followed by profound **primary optic atrophy**. **NEET-PG High-Yield Pearls:** * **Primary Optic Atrophy:** Occurs without previous disc edema (e.g., Pituitary tumor, Methanol, Traumatic injury). The disc appears chalky white with clear margins. * **Secondary Optic Atrophy:** Follows chronic papilledema or papillitis. The disc is greyish-white with poorly defined margins. * **Consecutive Optic Atrophy:** Follows retinal diseases like Retinitis Pigmentosa or Central Retinal Artery Occlusion (CRAO). The disc has a characteristic **waxy pallor**.

Q: What is Hutchinson's pupil?

None of the above. **Explanation:** **Hutchinson’s Pupil** is a classic clinical sign of an expanding intracranial mass lesion (typically an extradural hematoma). The underlying mechanism is **uncal herniation**, where the medial temporal lobe compresses the **ipsilateral 3rd cranial nerve (Oculomotor nerve)**. Since parasympathetic fibers (responsible for constriction) travel on the superficial aspect of the nerve, they are affected first, leading to a **fixed and dilated pupil** on the side of the lesion. **Why "None of the above" is correct:** Hutchinson’s pupil is characterized by a **dilated (mydriatic)** and non-reactive pupil, not a constricted or irregular one. It is a sign of neurosurgical emergency (increased ICP), not a chronic infection like syphilis. **Analysis of Incorrect Options:** * **Option A (Syphilis):** This is associated with **Argyll Robertson Pupil** ("Prostitute’s Pupil"), which is bilateral, small, irregular, and characterized by accommodation-reflex present but light-reflex absent. * **Option B (Unilateral constricted pupil):** This is seen in **Horner’s Syndrome** (due to sympathetic paralysis) or acute iridocyclitis. * **Option C (Irregular pupil):** This is typically seen in **Argyll Robertson Pupil** or due to **posterior synechiae** in uveitis. **High-Yield Clinical Pearls for NEET-PG:** * **Stages of Hutchinson’s Pupil:** 1. **Initial:** Brief pupillary constriction (due to 3rd nerve irritation). 2. **Intermediate:** Ipsilateral pupil becomes **fixed and dilated** (paralysis of parasympathetic fibers). 3. **Terminal:** Both pupils become fixed and dilated (bilateral 3rd nerve palsy as brainstem compression progresses). * **Mnemonic:** Hutchinson’s Pupil = **H**ead Injury / **H**erniation. * **Differential:** Do not confuse with **Hutchinson’s Triad** (Interstital keratitis, sensorineural deafness, and notched incisors) seen in Congenital Syphilis.

Q: A 25-year-old man presents with acute, painless loss of vision in the right eye. The appearance of the optic nerve of the right eye is hyperemic. What is the most likely diagnosis among the given options?

Leber hereditary optic neuropathy (LHON). ### Explanation **Correct Option: C. Leber Hereditary Optic Neuropathy (LHON)** **Why it is correct:** LHON is a mitochondrial DNA disorder (typically mutations at positions 11778, 3460, or 14484) that primarily affects young males. It presents as an **acute or subacute, painless, central vision loss**. The hallmark finding in the acute stage is a **hyperemic optic disc** with **pseudo-papilledema** (elevation without leakage on FFA) and peripapillary telangiectatic microangiopathy. While it starts unilaterally, the second eye is usually involved within weeks to months. **Why the other options are incorrect:** * **A. Vitamin B12 deficiency:** This causes nutritional optic neuropathy, which presents as **gradual, bilateral, and progressive** vision loss, not acute. The disc usually appears normal initially, progressing to temporal pallor. * **B. Ethambutol toxicity:** This is a dose-dependent toxic optic neuropathy. It presents with **bilateral, symmetrical, and gradual** reduction in vision and color perception (red-green). * **D. Dominant Optic Atrophy (Kjer’s type):** This is the most common hereditary optic atrophy but presents in **early childhood (4–6 years)** with very slow, insidious progression and characteristic **temporal wedge disc pallor**, not acute hyperemia. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Mitochondrial (Maternal inheritance); however, it shows a strong male predilection (85%). * **Triad of Acute LHON:** 1. Circumpapillary telangiectatic microangiopathy, 2. Swelling of the nerve fiber layer (Pseudo-papilledema), 3. Absence of leakage on Fluorescein Angiography (distinguishes it from true papilledema). * **Visual Field:** Typically shows a **centrocecal scotoma**. * **Treatment:** Idebenone (a potent antioxidant) is often used to improve visual outcomes.

Q: A patient presents with right homonymous hemianopia. What is the most likely site of the lesion?

Left optic radiation. ### Explanation The visual pathway is organized such that the **left side of the brain processes the right visual field** of both eyes, and vice versa. This crossover occurs at the optic chiasm. **1. Why Option A is Correct:** A **homonymous hemianopia** refers to the loss of the same half of the visual field in both eyes. This occurs due to a lesion **posterior to the optic chiasm** (retrochiasmal). Because the fibers from the left temporal retina and right nasal retina (both representing the right visual field) travel together in the **left** optic tract, lateral geniculate body, and optic radiations, a lesion in the **Left Optic Radiation** results in a Right Homonymous Hemianopia. **2. Why the other options are incorrect:** * **B & D (Right-sided lesions):** Lesions in the right geniculate body or right optic radiation would result in a **Left** Homonymous Hemianopia. * **C (Right optic nerve):** A lesion here occurs anterior to the chiasm. It would result in ipsilateral (right-sided) monocular vision loss or a central scotoma, not a bilateral field defect. **3. High-Yield Clinical Pearls for NEET-PG:** * **Congruity:** The more posterior the lesion (closer to the occipital cortex), the more "congruous" (identical in shape) the field defects in both eyes become. * **Pie in the Sky:** A lesion in the **Temporal lobe** (Meyer’s loop) causes a Superior Homonymous Quadrantanopia. * **Pie on the Floor:** A lesion in the **Parietal lobe** (Baum’s loop) causes an Inferior Homonymous Quadrantanopia. * **Macular Sparing:** Often seen in occipital lobe lesions (e.g., PCA stroke) due to collateral blood supply from the Middle Cerebral Artery (MCA).

Q: Occlusion of short posterior ciliary arteries may cause which of the following?

Ischaemic optic neuropathy. **Explanation:** The **short posterior ciliary arteries (SPCAs)**, typically numbering 15–20, are branches of the ophthalmic artery. Their primary anatomical role is to supply the **choroid** and the **optic nerve head (ONH)**. 1. **Why Option A is correct:** The SPCAs form the **Circle of Zinn-Haller**, an arterial anastomosis within the sclera that provides the main blood supply to the prelaminar and laminar portions of the optic nerve. Occlusion of these arteries leads to an interruption of blood flow to the optic nerve head, resulting in **Anterior Ischaemic Optic Neuropathy (AION)**. This presents clinically as sudden, painless vision loss with disc edema. 2. **Why Options B and C are incorrect:** * **Anterior segment ischaemia (Option C):** This is primarily caused by the occlusion of the **Long Posterior Ciliary Arteries (LPCAs)** and the **Anterior Ciliary Arteries** (derived from the recti muscles), which form the major arterial circle of the iris. * **Posterior segment ischaemia (Option B):** While the SPCAs supply the choroid, "posterior segment ischaemia" is a broad term. In medical exams, SPCA pathology is specifically linked to the optic nerve (AION). Furthermore, the retina (a major part of the posterior segment) is supplied by the **Central Retinal Artery**, not the SPCAs. **High-Yield Clinical Pearls for NEET-PG:** * **Circle of Zinn-Haller:** Formed by the anastomosis of short posterior ciliary arteries. * **AION:** Can be Arteritic (e.g., Giant Cell Arteritis) or Non-arteritic (associated with HTN/Diabetes). * **Blood Supply of Optic Nerve:** * Surface nerve fiber layer: Central retinal artery. * Prelaminar, Laminar, and Retrolaminar regions: Short posterior ciliary arteries.

Question 1

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 2

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

Question 3

Blind spot enlargement indicates:

Accepted Answer

Papilloedema

Answer

Retinal detachment

Answer

Avulsion of optic nerve

Answer

Papillitis

Question 4

A patient presents with diplopia with limitation of adduction in the left eye and abducting saccades in the right eye. Convergence is preserved. What is the most likely etiology?

Accepted Answer

Internuclear ophthalmoplegia

Answer

3rd nerve palsy

Answer

Duane's syndrome

Answer

Absence of medial rectus muscle

Question 5

Optic atrophy may occur in all of the following conditions, EXCEPT:

Accepted Answer

Leprosy

Answer

Glaucoma

Answer

Pituitary tumor

Answer

Methanol intake

Question 6

What is Hutchinson's pupil?

Accepted Answer

None of the above

Answer

Seen in syphilis

Answer

Unilateral constricted pupil

Answer

Irregular pupil

Question 7

Marcus Gunn pupil along with proptosis indicates which of the following?

Accepted Answer

Compression of the optic nerve

Answer

Involvement of the ciliary ganglion

Answer

Compression of the inferior division of the third nerve

Answer

Compression of sympathetic nerves of the eyeball

Question 8

A 25-year-old man presents with acute, painless loss of vision in the right eye. The appearance of the optic nerve of the right eye is hyperemic. What is the most likely diagnosis among the given options?

Accepted Answer

Leber hereditary optic neuropathy (LHON)

Answer

Vitamin B12 deficiency

Answer

Ethambutol hydrochloride toxicity

Answer

Dominant optic atrophy

Question 9

A patient presents with right homonymous hemianopia. What is the most likely site of the lesion?

Accepted Answer

Left optic radiation

Answer

Right geniculate body

Answer

Right optic nerve

Answer

Right optic radiation

Question 10

Occlusion of short posterior ciliary arteries may cause which of the following?

Accepted Answer

Ischaemic optic neuropathy

Answer

Posterior segment ischaemia

Answer

Anterior segment ischaemia

Answer

All of the above

Neuro-Ophthalmology — MCQs

Neuro-Ophthalmology — MCQs

On this page

Practice by Chapter

Want unlimited practice?