Neuro-Ophthalmology Practice Questions

Q: Which of the following ocular findings is a component of Foville's syndrome?

Lateral gaze palsy. **Explanation:** **Foville’s Syndrome** is a classic brainstem stroke syndrome involving the **dorsal pontine tegmentum**. It is typically caused by an occlusion of the paramedian branches of the basilar artery. **Why Option A is correct:** The syndrome is characterized by the involvement of the **Abducens nucleus (CN VI)** and the **Parapontine Reticular Formation (PPRF)**. Damage to these structures results in an **ipsilateral lateral gaze palsy** (the inability to look toward the side of the lesion). Additionally, the syndrome involves the **Facial nerve (CN VII)** fibers, leading to ipsilateral facial nerve palsy, and the corticospinal tract, causing contralateral hemiplegia. **Why other options are incorrect:** * **B. Medial gaze palsy:** This is typically seen in Internuclear Ophthalmoplegia (INO) due to a lesion in the Medial Longitudinal Fasciculus (MLF), not the PPRF/Abducens nucleus. * **C. 3rd nerve palsy:** This is a feature of midbrain syndromes (e.g., Weber’s or Benedikt’s syndrome), not pontine syndromes. * **D. Nystagmus:** While nystagmus can occur in various brainstem lesions, it is not a defining diagnostic component of Foville’s syndrome. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Foville’s:** Think of the "Face" (CN VII) and "Fields" (Gaze palsy). * **Millard-Gubler Syndrome vs. Foville’s:** Both involve CN VI and VII. However, Millard-Gubler involves the **nerve fibers** (causing diplopia), whereas Foville’s involves the **nucleus/PPRF** (causing conjugate gaze palsy). * **Key Triad of Foville’s:** 1. Ipsilateral conjugate gaze palsy, 2. Ipsilateral facial palsy, 3. Contralateral hemiparesis.

Q: Which nerve supplies the Levator Palpebrae Superioris?

Oculomotor nerve. **Explanation:** The **Levator Palpebrae Superioris (LPS)** is the primary muscle responsible for elevating the upper eyelid. It is embryologically derived from the same mass as the Superior Rectus muscle and is supplied by the **Superior Division of the Oculomotor Nerve (CN III)**. **Why the Oculomotor Nerve is Correct:** The Oculomotor nerve provides motor innervation to most extraocular muscles. Specifically, the superior division supplies the LPS and the Superior Rectus. A lesion of CN III results in significant **ptosis** (drooping of the eyelid) due to paralysis of the LPS. **Analysis of Incorrect Options:** * **Ophthalmic Nerve (V1):** This is a branch of the Trigeminal nerve. It provides **sensory** innervation to the eye, forehead, and upper eyelid, but it has no motor function for eyelid elevation. * **Abducens Nerve (CN VI):** This nerve purely supplies the **Lateral Rectus** muscle, responsible for abduction of the eye. * **Trochlear Nerve (CN IV):** This nerve purely supplies the **Superior Oblique** muscle, responsible for depression and intorsion. **Clinical Pearls for NEET-PG:** 1. **Dual Supply of Eyelid Elevation:** While the LPS (CN III) is the main elevator, the **Muscle of Müller** (sympathetic supply) provides additional "tone." Damage to sympatherics results in *partial ptosis* (seen in Horner’s Syndrome), whereas CN III palsy causes *complete ptosis*. 2. **Nucleus Anatomy:** The LPS is unique because it is supplied by a **single midline subnucleus** (the Central Caudal Nucleus) in the Oculomotor complex. Therefore, a single nuclear lesion can cause bilateral ptosis. 3. **Synkinesis:** The "Jaw-Winking" phenomenon (Marcus Gunn Phenomenon) occurs due to misdirected innervation between the Mandibular nerve (V3) and the nerve to the LPS.

Q: A young man presents with blurring of vision in the right eye, followed by the left eye after 3 months. Examination reveals disc hyperemia, edema, circumpapillary telangiectasia with normal pupillary response and centrocecal scotoma on perimetry. What is the most likely cause?

Leber's hereditary optic neuropathy. ### Explanation **Correct Answer: D. Leber's Hereditary Optic Neuropathy (LHON)** **Why it is correct:** LHON is a mitochondrially inherited degeneration of retinal ganglion cells. It typically affects young males (15–35 years). The clinical hallmark is **sequential, painless, subacute visual loss** (one eye followed by the other within weeks to months). The classic triad seen on fundoscopy during the acute phase includes: 1. **Circumpapillary telangiectasia** (microangiopathy). 2. **Pseudo-edema** of the optic disc (hyperemia and swelling of the nerve fiber layer without actual leakage on FFA). 3. **Absence of pupillary light reflex impairment** (initially) and absence of pain. Perimetry typically shows a **centrocecal scotoma**, reflecting damage to the papillomacular bundle. **Why incorrect options are wrong:** * **A. Typical Optic Neuritis:** Usually presents with **painful** eye movements and a significant **Relative Afferent Pupillary Defect (RAPD)**, which is absent here. * **B. Acute Papilledema:** This is bilateral disc swelling due to increased intracranial pressure. It usually presents with transient visual obscurations and enlarged blind spots, rather than early central vision loss or telangiectasia. * **C. Toxic Optic Neuropathy:** Usually presents with **simultaneous** (not sequential) bilateral vision loss and is associated with a history of tobacco, alcohol, or drug (Ethambutol) intake. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Mitochondrial (maternal) inheritance; point mutation at **11778** (most common), 3460, or 14484. * **FFA Finding:** Unlike true papilledema, the disc in LHON **does not leak** fluorescein (hence "pseudo-edema"). * **Prognosis:** Poor; however, the 14484 mutation has the highest rate of spontaneous recovery. * **Differential:** Always consider LHON in a young male with sequential painless vision loss and a "swollen" disc that doesn't leak on FFA.

Q: The frequency of colour-blind males is 1 in 100 in a certain population. What is the frequency of colour blind females, assuming the population is in Hardy-Weinberg equilibrium?

0.0001. **Explanation:** This question integrates genetics with ophthalmology, focusing on the inheritance pattern of **Congenital Color Blindness**, which is an **X-linked recessive** trait. **1. Why Option D is Correct:** In Hardy-Weinberg equilibrium, the frequency of an allele is represented by $p$ (dominant) and $q$ (recessive). * **For Males (XY):** Since males have only one X chromosome, the frequency of affected males is equal to the gene frequency ($q$). * Given: 1 in 100 males are color blind $\rightarrow q = 0.01$. * **For Females (XX):** For a female to be color blind, she must possess two recessive alleles ($q^2$). * Calculation: $q^2 = (0.01)^2 = 0.0001$. * Therefore, the frequency of color-blind females is **0.0001** (1 in 10,000). **2. Why Other Options are Incorrect:** * **Option A (0.02) & C (0.01):** These represent the allele frequency ($q$) or double the frequency, which does not account for the requirement of two X chromosomes in females for trait expression. * **Option B (0.0005):** This is a mathematical miscalculation and does not follow the $q^2$ rule for homozygous recessive traits. **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **Inheritance:** Red-green color blindness (Protanopia/Deuteranopia) is X-linked recessive, explaining why it is significantly more common in males (~8%) than females (~0.4-0.5%). * **Ishihara Chart:** The gold standard screening test for red-green deficiency. It must be read at 75 cm under natural daylight. * **Edridge-Green Lantern Test:** Used for occupational screening (e.g., Railways, Pilots) to assess functional color vision. * **Acquired Color Blindness:** Follows **Kollner’s Rule**: * Outer retinal/media diseases $\rightarrow$ Blue-yellow defects. * Optic nerve diseases $\rightarrow$ Red-green defects (Exception: Glaucoma and Papilledema cause blue-yellow defects initially).

Q: The nerve most frequently involved in herpes zoster ophthalmicus is:

Frontal nerve. **Explanation:** Herpes Zoster Ophthalmicus (HZO) occurs due to the reactivation of the Varicella-Zoster Virus (VZV) dormant in the **Trigeminal (V) ganglion**. The virus travels down the **Ophthalmic division (V1)** of the trigeminal nerve. **Why Frontal Nerve is the Correct Answer:** The Ophthalmic nerve (V1) divides into three branches: Frontal, Nasociliary, and Lacrimal. Among these, the **Frontal nerve** is the largest and most frequently involved branch in HZO. It further divides into the supraorbital and supratrochlear nerves, supplying the skin of the forehead and upper eyelid. **Analysis of Incorrect Options:** * **Nasociliary nerve:** While less frequently involved than the frontal nerve, its involvement is clinically significant. It supplies the eyeball; hence, its involvement (indicated by **Hutchinson’s sign**) carries a high risk of intraocular complications like uveitis or keratitis. * **Lacrimal nerve:** This is the smallest branch of V1 and is the least commonly involved of the three. * **Facial nerve:** The facial nerve (CN VII) is a motor nerve to the muscles of facial expression. While it can be involved in Ramsay Hunt Syndrome (Geniculate ganglion), it is not a branch of the trigeminal nerve and is not the primary site for HZO. **High-Yield Clinical Pearls for NEET-PG:** 1. **Hutchinson’s Sign:** Vesicles on the tip or side of the nose indicate nasociliary nerve involvement and predict a higher likelihood of ocular inflammation. 2. **Most common ocular complication:** Chronic epithelial keratitis or anterior uveitis. 3. **Treatment:** Oral Acyclovir (800 mg 5 times daily for 7–10 days) is the gold standard, ideally started within 72 hours of rash onset. 4. **Post-herpetic neuralgia:** The most common debilitating complication in the elderly.

Q: A patient presents with unilateral painful ophthalmoplegia. Imaging revealed an enlargement of the cavernous sinus on the affected side. What is the likely diagnosis?

Tolosa-Hunt Syndrome. **Explanation:** **Tolosa-Hunt Syndrome (THS)** is the correct diagnosis. It is characterized by idiopathic, non-specific granulomatous inflammation of the cavernous sinus, superior orbital fissure, or orbital apex. * **Clinical Presentation:** Patients present with **painful ophthalmoplegia** (cranial nerves III, IV, and VI involvement) and dramatic responsiveness to systemic corticosteroids. * **Imaging:** MRI typically shows enlargement or "fullness" of the cavernous sinus due to inflammatory tissue, which explains the findings in this case. **Analysis of Incorrect Options:** * **Gradenigo Syndrome:** This involves a triad of suppurative otitis media, abducens nerve (CN VI) palsy, and trigeminal (CN V) pain. It is caused by **petrous apicitis**, not cavernous sinus enlargement. * **Cavernous Sinus Thrombosis (CST):** While it presents with painful ophthalmoplegia, it is usually an acute, life-threatening infectious process (often following a facial infection) presenting with high fever, proptosis, and chemosis. Imaging would show filling defects/thrombus rather than simple enlargement. * **Orbital Pseudotumor:** This is an idiopathic inflammation of the **orbit** itself. While it causes pain and restricted eye movements, the pathology is localized to the extraocular muscles or globe, not the cavernous sinus. **High-Yield Pearls for NEET-PG:** * **Diagnosis of Exclusion:** THS is diagnosed only after ruling out tumors, sarcoidosis, and infections. * **Steroid Test:** A rapid clinical improvement (within 48–72 hours) after starting high-dose steroids is a diagnostic hallmark of THS. * **Nerves Involved:** CN III is most commonly affected, followed by VI and IV. Sensory loss in the V1/V2 distribution may also occur.

Question 1

A female presented with loss of vision in both eyes. On examination, she has normal pupillary responses and a normal fundus. Her visually evoked response (VER) examination shows extinguished responses. What is the most likely diagnosis?

Accepted Answer

Cortical blindness

Answer

Hysteria

Answer

Optic neuritis

Answer

Retinal detachment

Question 2

Which of the following ocular findings is a component of Foville's syndrome?

Accepted Answer

Lateral gaze palsy

Answer

Medial gaze palsy

Answer

3rd nerve palsy

Answer

Nystagmus

Question 3

Which nerve supplies the Levator Palpebrae Superioris?

Accepted Answer

Oculomotor nerve

Answer

Ophthalmic nerve

Answer

Abducens nerve

Answer

Trochlear nerve

Question 4

A young man presents with blurring of vision in the right eye, followed by the left eye after 3 months. Examination reveals disc hyperemia, edema, circumpapillary telangiectasia with normal pupillary response and centrocecal scotoma on perimetry. What is the most likely cause?

Accepted Answer

Leber's hereditary optic neuropathy

Answer

Typical optic neuritis

Answer

Acute papilledema

Answer

Toxic optic neuropathy

Question 5

The frequency of colour-blind males is 1 in 100 in a certain population. What is the frequency of colour blind females, assuming the population is in Hardy-Weinberg equilibrium?

Accepted Answer

0.0001

Answer

0.02

Answer

0.0005

Answer

0.01

Question 6

The nerve most frequently involved in herpes zoster ophthalmicus is:

Accepted Answer

Frontal nerve

Answer

Nasociliary nerve

Answer

Lacrimal nerve

Answer

Facial nerve

Question 7

A patient presents with unilateral painful ophthalmoplegia. Imaging revealed an enlargement of the cavernous sinus on the affected side. What is the likely diagnosis?

Accepted Answer

Tolosa-Hunt Syndrome

Answer

Gradenigo syndrome

Answer

Cavernous sinus thrombosis

Answer

Orbital pseudotumor

Question 8

When a small target is oscillated in front of a patient with binocular vision, the patient sees the movement of the object in an elliptical orbit rather than a to-and-fro path. What is this phenomenon known as?

Accepted Answer

Pulfrich phenomenon

Answer

Oppenheim phenomenon

Answer

Uthoff phenomenon

Answer

Paroxysmal convergence spasm phenomenon

Question 9

Defect in amblyopia lies in which structure?

Accepted Answer

Lateral geniculate body

Answer

Afferent pupillary reflex

Answer

Rods and cones

Answer

Retina

Question 10

A 50-year-old male patient with a history of sexually transmitted disease acquired 20 years ago presents with headache, seizures, confusion, and numbness in the extremities. What is the expected pupillary response in this patient?

Accepted Answer

The light reflex is absent, but the accommodation reflex is present.

Answer

Both light reflex and accommodation reflex are absent.

Answer

Both light reflex and accommodation reflex are present.

Answer

The light reflex is present, but the accommodation reflex is absent.

Neuro-Ophthalmology — MCQs

Neuro-Ophthalmology — MCQs

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