Neuro-Ophthalmology — MCQs

Neuro-Ophthalmology Indian Medical PG Practice Questions and MCQs

Question 161: Unilateral sudden complete loss of vision (Amaurosis fugax) is typically due to a lesion in which artery?

A. Internal carotid artery (Correct Answer)
B. Middle cerebral artery
C. Anterior cerebral artery
D. Basilar artery

Explanation: **Explanation:** **Amaurosis Fugax** (transient monocular blindness) is characterized by a sudden, painless, temporary loss of vision in one eye, often described by patients as a "curtain falling" over their field of vision. **Why Option A is Correct:** The **Internal Carotid Artery (ICA)** is the parent vessel of the **Ophthalmic Artery**, which further gives rise to the **Central Retinal Artery**. The most common cause of amaurosis fugax is an embolus (Hollenhorst plaque) originating from an atherosclerotic plaque at the carotid bifurcation. Because the ophthalmic artery is the first major branch of the ICA, an embolic event or significant stenosis in the ICA directly compromises blood flow to the retina, leading to unilateral vision loss. **Why Other Options are Incorrect:** * **Middle Cerebral Artery (MCA) & Anterior Cerebral Artery (ACA):** These are terminal branches of the ICA that supply the brain parenchyma. A lesion here would cause contralateral motor/sensory deficits or homonymous hemianopia (bilateral field defects), not unilateral blindness. * **Basilar Artery:** This is part of the posterior circulation. A lesion here typically results in bilateral visual symptoms (cortical blindness), vertigo, or cranial nerve palsies, rather than isolated monocular loss. **High-Yield Clinical Pearls for NEET-PG:** * **Hollenhorst Plaques:** These are bright, cholesterol emboli seen at retinal artery bifurcations during fundoscopy; they are pathognomonic for carotid artery disease. * **Diagnostic Gold Standard:** Carotid Doppler/Duplex ultrasound is the initial investigation of choice to evaluate ICA stenosis in patients with amaurosis fugax. * **Giant Cell Arteritis (GCA):** Always consider GCA in elderly patients with transient vision loss; however, the classic "embolic" amaurosis fugax is primarily associated with ICA disease.

Question 162: In Foster-Kennedy syndrome, what funduscopic findings are typically observed?

A. Ipsilateral optic disc edema and contralateral optic atrophy
B. Ipsilateral optic atrophy and contralateral optic disc edema (Correct Answer)
C. Ipsilateral optic disc edema and optic atrophy
D. Contralateral optic disc edema and optic atrophy

Explanation: ### Explanation **Foster-Kennedy Syndrome** is a classic neuro-ophthalmological triad caused by a space-occupying lesion (typically a **frontal lobe tumor** or **olfactory groove meningioma**). #### 1. Why Option B is Correct The syndrome occurs due to two distinct mechanisms acting simultaneously: * **Ipsilateral Optic Atrophy:** The tumor directly compresses the optic nerve on the same side as the lesion. Chronic compression leads to the death of retinal ganglion cells, resulting in primary optic atrophy. * **Contralateral Papilledema (Disc Edema):** As the tumor grows, it increases intracranial pressure (ICP). This generalized rise in ICP is transmitted through the subarachnoid space to the opposite optic nerve, causing disc edema. The ipsilateral side does not develop edema because the compressed, atrophic nerve fibers cannot swell. #### 2. Why Other Options are Wrong * **Option A:** This is the reverse of the actual pathology. Direct compression (atrophy) happens on the side of the lesion, not the opposite side. * **Options C & D:** These suggest both findings occur in the same eye. In Foster-Kennedy, the findings are characteristically dissociated between the two eyes. #### 3. Clinical Pearls for NEET-PG * **The Triad:** 1. Ipsilateral optic atrophy, 2. Contralateral papilledema, 3. Ipsilateral anosmia (loss of smell due to pressure on the olfactory bulb). * **Pseudo-Foster-Kennedy Syndrome:** This is more common than the true syndrome. It is typically caused by **Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION)**, where one eye has old atrophy and the other has new acute edema, but without an intracranial mass or increased ICP. * **Most Common Cause:** Olfactory groove meningioma. * **Visual Fields:** The eye with atrophy will show a central or centrocecal scotoma, while the eye with edema may show an enlarged blind spot.

Question 163: Horner's syndrome is characterized by which of the following findings, except?

A. Ptosis
B. Marcus Gunn pupil (Correct Answer)
C. Anhydrosis
D. Sympathetic lesion

Explanation: **Explanation:** Horner’s syndrome results from a lesion along the **sympathetic pathway** (3-neuron arc) supplying the eye and face. The classic clinical triad includes **Ptosis, Miosis, and Anhydrosis.** * **Why Marcus Gunn Pupil is the correct answer:** A Marcus Gunn pupil, or **Relative Afferent Pupillary Defect (RAPD)**, is a sign of an **afferent** pathway lesion (typically the optic nerve or extensive retinal disease). In Horner’s syndrome, the afferent pathway is intact; the pathology lies in the **efferent sympathetic** (motor) supply. Therefore, RAPD is not a feature of Horner’s. * **Analysis of incorrect options:** * **Ptosis (Option A):** Occurs due to paralysis of **Müller’s muscle** (superior tarsal muscle). It is typically mild (1–2 mm) compared to the complete ptosis seen in 3rd nerve palsy. * **Anhydrosis (Option C):** Refers to the loss of sweating on the affected side of the face. It occurs if the lesion is proximal to the bifurcation of the carotid artery (1st or 2nd order neurons). * **Sympathetic lesion (Option D):** This is the fundamental etiology of Horner’s syndrome. The pathway starts in the hypothalamus, descends to the ciliospinal center of Budge (C8-T2), and travels via the superior cervical ganglion to the eye. **High-Yield Clinical Pearls for NEET-PG:** 1. **Miosis:** The pupil is small due to unopposed parasympathetic action; dilation lag is seen in dark conditions. 2. **Apparent Enophthalmos:** The narrowing of the palpebral fissure gives a false impression that the eye is sunken. 3. **Heterochromia Iridum:** Seen in **congenital** Horner’s syndrome (the affected iris is lighter). 4. **Pharmacological Testing:** * **Cocaine (4-10%):** Fails to dilate a Horner’s pupil (Diagnostic). * **Apraclonidine (0.5-1%):** Causes reversal of anisocoria (dilates the Horner’s pupil). * **Hydroxyamphetamine:** Used to differentiate pre-ganglionic from post-ganglionic lesions.

Question 164: Which of the following is a feature of unilateral oculomotor nerve palsy?

A. Drooping of eyelid (Correct Answer)
B. Accommodation reflex is absent
C. Visual loss
D. Pupillary light reflex is completely absent

Explanation: **Explanation:** The **3rd Cranial Nerve (Oculomotor nerve)** supplies the Levator Palpebrae Superioris (LPS), which is the primary muscle responsible for elevating the upper eyelid. In Oculomotor nerve palsy, the loss of nerve supply to the LPS leads to **Ptosis (drooping of the eyelid)**. This is typically a complete and severe ptosis. **Analysis of Options:** * **Option A (Correct):** Drooping of the eyelid (Ptosis) occurs due to paralysis of the LPS muscle. * **Option B (Incorrect):** While the motor limb of the accommodation reflex (via the ciliary muscle) is affected, the reflex is not necessarily "absent" in all cases of 3rd nerve palsy. For example, in **pupil-sparing** 3rd nerve palsy (common in Diabetes), the parasympathetic fibers are intact, and accommodation may be preserved. * **Option C (Incorrect):** The 3rd nerve is a purely motor and parasympathetic nerve. It has no sensory component for vision; therefore, visual acuity remains normal unless the eyelid physically blocks the pupil. * **Option D (Incorrect):** The pupillary light reflex is not "completely" absent because the **afferent limb (CN II)** is still functional. Only the efferent response (constriction) in the affected eye is lost. Furthermore, in medical causes like Diabetes, the pupil is often spared entirely. **High-Yield Clinical Pearls for NEET-PG:** 1. **The "Down and Out" Eye:** Due to the unopposed action of the Superior Oblique (CN IV) and Lateral Rectus (CN VI), the eye deviates downwards and outwards. 2. **Pupil-Sparing vs. Pupil-Involving:** * **Pupil-Sparing:** Suggests **Ischemic** causes (e.g., Diabetes, Hypertension) because the microangiopathy affects the central fibers but spares the peripheral parasympathetic fibers. * **Pupil-Involving:** Suggests **Compressive** lesions (e.g., P-Comm Artery Aneurysm) because parasympathetic fibers are located superficially on the nerve. 3. **Mydriasis:** If the pupil is involved, it will be fixed and dilated.

Question 165: Unilateral papilledema with optic atrophy on the other side is a feature of?

A. Foster Kennedy syndrome (Correct Answer)
B. Fisher syndrome
C. Vogt-Koyanagi-Harada syndrome
D. WAGR syndrome

Explanation: **Explanation:** **Foster Kennedy Syndrome** is a classic neuro-ophthalmological triad caused by a space-occupying lesion (SOL), most commonly a **frontal lobe tumor** (e.g., olfactory groove meningioma). The underlying mechanism is dual: 1. **Ipsilateral Optic Atrophy:** Direct pressure from the tumor on the optic nerve causes nerve fiber death and atrophy on the side of the lesion. 2. **Contralateral Papilledema:** As the tumor grows, it increases intracranial pressure (ICP), which is transmitted to the healthy optic nerve on the opposite side, causing disc edema. *Note: Anosmia (loss of smell) is often the third component of the triad due to pressure on the olfactory bulb.* **Analysis of Incorrect Options:** * **Fisher Syndrome (Miller Fisher Syndrome):** A variant of Guillain-Barré syndrome characterized by the triad of ataxia, areflexia, and ophthalmoplegia. It does not involve asymmetric disc changes. * **Vogt-Koyanagi-Harada (VKH) Syndrome:** A multisystem autoimmune disorder involving bilateral granulomatous panuveitis, exudative retinal detachment, and integumentary signs (poliosis, vitiligo). It typically presents with bilateral involvement. * **WAGR Syndrome:** A genetic syndrome consisting of **W**ilms tumor, **A**niridia, **G**enitourinary anomalies, and mental **R**etardation. **High-Yield Clinical Pearls for NEET-PG:** * **Pseudo-Foster Kennedy Syndrome:** Occurs without a tumor, often due to sequential Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION). One eye has old atrophy, and the other has acute disc edema. * **Most common cause:** Olfactory groove meningioma. * **Key Triad:** Ipsilateral optic atrophy, contralateral papilledema, and ipsilateral anosmia.

Question 166: A 26-year-old male presents with restriction of eye movements in all directions and moderate ptosis, but without diplopia or squint. What is the most likely diagnosis?

A. Thyroid ophthalmopathy
B. Chronic progressive external ophthalmoplegia (Correct Answer)
C. Myasthenia gravis
D. Multiple cranial nerve palsies

Explanation: **Explanation:** The clinical presentation of symmetric, global restriction of eye movements accompanied by ptosis, but notably **without diplopia or squint**, is the hallmark of **Chronic Progressive External Ophthalmoplegia (CPEO)**. **1. Why CPEO is correct:** CPEO is a mitochondrial myopathy characterized by a slow, progressive, and symmetric weakness of the extraocular muscles. Because the involvement is **symmetric** in both eyes, the visual axes remain aligned even as motility decreases. This explains the absence of diplopia (double vision) and squint (strabismus). The levator palpebrae superioris is also affected, leading to bilateral ptosis. **2. Why other options are incorrect:** * **Thyroid Ophthalmopathy:** Typically presents with lid retraction (not ptosis), proptosis, and restrictive squint (leading to diplopia) due to fibrosis of specific muscles (most commonly the Inferior Rectus). * **Myasthenia Gravis:** While it causes ptosis and ophthalmoplegia, it is characterized by **variability and fatigue**. Diplopia is a very common early symptom because the muscle involvement is usually asymmetric. * **Multiple Cranial Nerve Palsies:** Lesions in the cavernous sinus or orbital apex would cause acute or subacute ophthalmoplegia. These are rarely perfectly symmetric, usually causing significant diplopia and often involving pupillary changes or pain. **High-Yield Clinical Pearls for NEET-PG:** * **Kearns-Sayre Syndrome (KSS):** A triad of CPEO, pigmentary retinopathy, and cardiac conduction defects (requires a pacemaker). Always screen CPEO patients with an ECG. * **Biopsy Finding:** Skeletal muscle biopsy in mitochondrial diseases like CPEO shows **"Ragged Red Fibers"** (Gomori trichrome stain). * **Pupillary Sparing:** In CPEO, the internal ocular muscles (pupil and ciliary muscle) are always spared.

Question 167: Muller's muscle is supplied by which nerve fibers?

A. 3rd cranial nerve
B. 4th cranial nerve
C. Sympathetic fibers (Correct Answer)
D. Parasympathetic fibers

Explanation: **Explanation:** The **Muller’s muscle** (also known as the superior tarsal muscle) is a smooth muscle located in the upper eyelid. Unlike the skeletal muscles of the eye, it is under the control of the **autonomic nervous system**, specifically the **sympathetic fibers**. 1. **Why Sympathetic fibers are correct:** These fibers originate from the superior cervical ganglion, travel along the internal carotid artery, and eventually reach the muscle. The Muller’s muscle provides approximately 2 mm of additional eyelid elevation (tonic lift). Sympathetic stimulation maintains an "alert" wide-eyed appearance. 2. **Why other options are incorrect:** * **3rd Cranial Nerve (Oculomotor):** This nerve supplies the **Levator Palpebrae Superioris (LPS)**, which is the primary skeletal muscle responsible for elevating the eyelid. While both muscles lift the lid, their innervation is distinct. * **4th Cranial Nerve (Trochlear):** This nerve exclusively supplies the Superior Oblique extraocular muscle. * **Parasympathetic fibers:** These are responsible for pupillary constriction (sphincter pupillae) and accommodation (ciliary muscle), not eyelid elevation. **Clinical Pearls for NEET-PG:** * **Horner’s Syndrome:** Damage to the sympathetic pathway leads to paralysis of Muller’s muscle, resulting in **partial ptosis** (1-2 mm), along with miosis and anhidrosis. * **LPS vs. Muller’s:** Complete ptosis occurs with 3rd nerve palsy (LPS involvement), whereas partial ptosis occurs in Horner’s syndrome (Muller’s involvement). * **Thyroid Eye Disease:** Overactivation of sympathetic fibers can cause Muller’s muscle contraction, leading to the characteristic **lid retraction** seen in Graves' ophthalmopathy.

Question 168: A patient's eye examination reveals bilaterally small pupils with a normal reaction to the near reflex but an absent light reflex, leading to a diagnosis of Argyll Robertson pupil. Which of the following conditions is classically associated with Argyll Robertson pupil?

A. Multiple sclerosis
B. Midbrain tumor
C. Neurosyphilis (Correct Answer)
D. All of the above

Explanation: ### Explanation **Argyll Robertson Pupil (ARP)** is a classic neuro-ophthalmological finding characterized by **Light-Near Dissociation (LND)**. In this condition, the pupils are typically small, irregular, and bilateral; they do not constrict when exposed to light (absent light reflex) but do constrict during accommodation (normal near reflex). **Why Neurosyphilis is Correct:** The classic association for ARP is **Tertiary Syphilis (Neurosyphilis)**, specifically *Tabes Dorsalis*. The underlying pathophysiology involves a lesion in the **tectotegmental tract** in the pretectal area of the midbrain. This lesion interrupts the fibers from the pretectal nucleus to the Edinger-Westphal (EW) nucleus (responsible for the light reflex) while sparing the more ventral fibers responsible for the near reflex. **Why Other Options are Incorrect:** * **Multiple Sclerosis (MS):** While MS can cause various pupillary abnormalities (like an Afferent Pupillary Defect/Marcus Gunn Pupil due to optic neuritis), it is not the classic cause of the small, miotic ARP. * **Midbrain Tumor:** Lesions in the dorsal midbrain (e.g., Pinealoma) cause **Parinaud’s Syndrome**. While this also presents with Light-Near Dissociation, the pupils are typically **large/mid-dilated**, not small/miotic as seen in ARP. This is often called the "Pseudo-Argyll Robertson Pupil." **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for ARP:** "**A**ccommodation **R**etained, **P**upillary reflex absent" (or **A**lmost **R**eacts to **P**rostitutes—referencing its historical association with syphilis). * **Site of Lesion:** Periaqueductal gray matter/Pretectal nucleus of the midbrain. * **Differential for LND:** Adie’s Tonic Pupil (unilateral, dilated), Parinaud’s Syndrome (large pupils), and Diabetes Mellitus. * **ARP vs. Adie’s:** ARP is bilateral and miotic (small); Adie’s is usually unilateral and mydriatic (large).

Question 169: Which one of the following is an oculotoxic drug?

A. Isoniazid
B. Ethambutol (Correct Answer)
C. Streptomycin
D. Rifampin

Explanation: **Explanation:** **Ethambutol** is a classic example of an oculotoxic drug and is a high-yield topic in NEET-PG. It is known to cause **dose-dependent optic neuritis**, which can be either retrobulbar or axial. The underlying mechanism involves the chelation of copper, which interferes with mitochondrial enzymes in the optic nerve, leading to demyelination. * **Clinical Presentation:** Patients typically present with a gradual, painless decrease in visual acuity, **central or centrocecal scotomas**, and a characteristic **loss of red-green color vision** (often the earliest sign). * **Management:** The toxicity is usually reversible if the drug is discontinued early. Baseline and monthly ophthalmological examinations (visual acuity, Ishihara color plates, and perimetry) are mandatory for patients on high-dose therapy (>15 mg/kg). **Analysis of Incorrect Options:** * **A. Isoniazid:** While it can rarely cause optic neuritis, its primary systemic toxicity is peripheral neuropathy (prevented by Pyridoxine/Vit B6) and hepatotoxicity. * **C. Streptomycin:** This aminoglycoside is primarily **ototoxic** (affecting the 8th cranial nerve, leading to vertigo and hearing loss) and nephrotoxic, rather than oculotoxic. * **D. Rifampin:** Known for causing orange-red discoloration of body fluids (tears, urine, sweat), it does not typically cause structural or functional ocular toxicity. **High-Yield Clinical Pearls:** 1. **Early Sign:** Impaired red-green color perception is the earliest indicator of Ethambutol toxicity. 2. **Dose Correlation:** Toxicity is rare at 15 mg/kg but increases significantly at doses >25 mg/kg. 3. **Other Oculotoxic Drugs:** Chloroquine/Hydroxychloroquine (Bull’s eye maculopathy), Amiodarone (Vortex keratopathy), and Vigabatrin (Visual field constriction).

Question 170: Waxy pallor of the optic disc is a characteristic finding in which disease?

A. Retinitis pigmentosa (Correct Answer)
B. Retinopathy of prematurity
C. Hypertensive retinopathy
D. Diabetic retinopathy

Explanation: **Explanation:** The correct answer is **Retinitis pigmentosa (RP)**. The characteristic appearance of the optic disc in RP is described as **"waxy pallor."** This occurs due to reactive gliosis and the formation of a glial membrane over the disc surface, rather than true primary optic atrophy. **Why Retinitis Pigmentosa is correct:** Retinitis pigmentosa is a hereditary dystrophy of the photoreceptors (primarily rods). It is characterized by a classic clinical triad: 1. **Arteriolar attenuation:** Severe narrowing of retinal vessels. 2. **Bony spicule pigmentation:** Mid-peripheral pigment migration. 3. **Waxy pallor of the optic disc:** Secondary to glial proliferation. **Why the other options are incorrect:** * **Retinopathy of Prematurity (ROP):** Characterized by peripheral neovascularization, fibrovascular proliferation, and "plus disease" (tortuosity). It may lead to tractional retinal detachment but does not typically present with waxy disc pallor. * **Hypertensive Retinopathy:** Features include arteriolar narrowing, AV nipping, flame-shaped hemorrhages, and cotton wool spots. In Grade IV (Malignant Hypertension), **optic disc edema** (papilledema) is seen, not waxy pallor. * **Diabetic Retinopathy:** Characterized by microaneurysms, hard exudates, and neovascularization. While advanced cases can lead to optic neuropathy, waxy pallor is not a defining feature. **High-Yield Clinical Pearls for NEET-PG:** * **Primary Optic Atrophy:** Chalky white disc (e.g., Multiple Sclerosis). * **Secondary Optic Atrophy:** Dirty grey disc with blurred margins (follows chronic papilledema). * **Glaucomatous Atrophy:** Deep cupping with nasal shifting of vessels. * **RP Associations:** Usher syndrome (hearing loss), Laurence-Moon-Bardet-Biedl syndrome (obesity, polydactyly, hypogonadism).

Practice by Chapter

Anatomy of Visual Pathways

Practice Questions

Pupillary Disorders

Practice Questions

Optic Neuritis

Practice Questions

Ischemic Optic Neuropathies

Practice Questions

Other Optic Neuropathies

Practice Questions

Papilledema

Practice Questions

Cranial Nerve Palsies

Practice Questions

Nystagmus

Practice Questions

Visual Field Defects

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Neuro-ophthalmic Manifestations of Intracranial Lesions

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Functional Visual Disorders

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Migraine and the Eye

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