Neuro-Ophthalmology Practice Questions

Q: Homonymous hemianopia with macular sparing is seen in:

Lesions of the visual cortex. **Explanation:** **1. Why Option A is Correct:** Homonymous hemianopia with macular sparing is the hallmark of a lesion in the **visual cortex (occipital lobe)**. The macula is spared due to two primary reasons: * **Dual Blood Supply:** The visual cortex receives blood from both the **Posterior Cerebral Artery (PCA)** and the **Middle Cerebral Artery (MCA)**. In a PCA stroke (the most common cause of cortical blindness), the MCA continues to supply the occipital pole where the macula is represented. * **Large Cortical Representation:** The macula occupies a disproportionately large area of the visual cortex (macular magnification), making it more resilient to small focal lesions. **2. Why Other Options are Incorrect:** * **Optic Radiations (Option B):** Lesions here typically cause a complete homonymous hemianopia **without** macular sparing. Depending on the fiber bundle involved, they may also cause quadrantanopias (e.g., "Pie in the sky" for temporal lobe/Meyer’s loop or "Pie on the floor" for parietal lobe/Baum’s loop). * **Lateral Geniculate Body (Option C):** Lesions here are rare and usually result in incongruous homonymous hemianopia or specific sectoral defects (like horizontal sectoranopia) depending on the blood supply involved (Anterior vs. Posterior Choroidal arteries). **3. NEET-PG High-Yield Pearls:** * **Congruity:** The more posterior the lesion (closer to the cortex), the more **congruous** (identical in both eyes) the visual field defect. * **Macular Sparing vs. Macular Splitting:** Macular **sparing** points to the Occipital Cortex; Macular **splitting** (the vertical line goes straight through the macula) points to the Optic Tract. * **Most common cause:** PCA occlusion is the most frequent cause of homonymous hemianopia with macular sparing.

Q: Down and out deviation of the eyeball is due to paralysis of which cranial nerve?

Cranial nerve III. **Explanation:** The characteristic **"down and out"** position of the eyeball is a hallmark clinical sign of **Cranial Nerve III (Oculomotor nerve) palsy**. **1. Why Option B is Correct:** The Oculomotor nerve innervates the majority of the extraocular muscles: Superior Rectus, Inferior Rectus, Medial Rectus, and Inferior Oblique. It also supplies the Levator Palpebrae Superioris (LPS). When CN III is paralyzed: * The **Superior Oblique** (CN IV) and **Lateral Rectus** (CN VI) remain functional and are now unopposed. * The **Lateral Rectus** pulls the eye laterally (**Out**). * The **Superior Oblique** abducts and depresses the eye (**Down**). * Additionally, patients typically present with **ptosis** (due to LPS weakness) and a **dilated, non-reactive pupil** (if parasympathetic fibers are involved). **2. Why the Other Options are Incorrect:** * **Option A (CN II):** The Optic nerve is purely sensory (vision). Damage leads to vision loss and pupillary reflex defects (RAPD), not ocular deviation. * **Option C (CN VI):** The Abducens nerve innervates the Lateral Rectus. Paralysis leads to an **inward (medial) deviation** (Esotropia) because the Medial Rectus is unopposed. * **Option D (CN IX):** The Glossopharyngeal nerve is a cranial nerve involved in taste, swallowing, and the gag reflex; it has no role in eye movements. **High-Yield Clinical Pearls for NEET-PG:** * **Medical CN III Palsy (Pupil Sparing):** Often due to Diabetes or Hypertension (ischemia of central fibers). * **Surgical CN III Palsy (Pupil Involved):** Often due to compression by a **Posterior Communicating Artery (PCom) aneurysm**. This is a neurosurgical emergency. * **Rule of thumb:** If the pupil is "fixed and dilated" in a CN III palsy, suspect external compression (aneurysm/uncal herniation).

Q: Parietal lobe tumors may be associated with which of the following visual field defects?

Contralateral lower homonymous quadrantanopia. **Explanation:** The visual pathway travels from the optic tract to the Lateral Geniculate Body (LGB) [1]. From the LGB, the optic radiations carry visual information to the primary visual cortex (V1). These radiations split into two distinct bundles [2]: 1. **Superior Optic Radiations (Parietal Lobe):** These fibers carry information from the **superior retina**, which corresponds to the **inferior (lower) visual field**. A lesion here results in a **Contralateral Lower Homonymous Quadrantanopia** (often described as "Pie in the floor") [2]. 2. **Inferior Optic Radiations (Temporal Lobe/Meyer’s Loop):** These fibers carry information from the **inferior retina**, which corresponds to the **superior (upper) visual field**. A lesion here results in a **Contralateral Upper Homonymous Quadrantanopia** ("Pie in the sky") [2]. **Analysis of Options:** * **Option A (Correct):** Parietal lobe tumors compress the superior optic radiations, leading to a loss of the lower quadrant of the visual field on the opposite side [2]. * **Option B (Incorrect):** This defect is characteristic of **Temporal lobe** lesions (Meyer’s loop involvement) [2]. * **Option C & D (Incorrect):** The anatomical segregation of fibers ensures that parietal and temporal lesions produce distinct, non-overlapping quadrantanopias. **High-Yield Clinical Pearls for NEET-PG:** * **Parietal Lobe Triad:** Lower quadrantanopia + Sensory loss + Gerstmann Syndrome (if dominant hemisphere). * **Temporal Lobe Triad:** Upper quadrantanopia + Wernicke’s aphasia + Auditory/Olfactory hallucinations. * **Macular Sparing:** Characteristically seen in **Occipital lobe** lesions (due to dual blood supply from MCA and PCA) [3]. * **Mnemonic:** **P**arietal = **P**ie on the floor (Lower); **T**emporal = **T**op of the sky (Upper).

Q: Which of the following is an ocular false localizing sign of raised intracranial pressure?

All of the above. **Explanation:** A **false localizing sign** is a neurological deficit that points to a specific anatomical location, but is actually caused by remote effects (such as displacement of brain structures or vascular compromise) due to generalized **raised intracranial pressure (ICP)**. * **Option A (6th Nerve Palsy):** This is the most common false localizing sign. The Abducens nerve has the longest intracranial course. When ICP rises, the brainstem is pushed downwards, stretching the nerve against the sharp petrous part of the temporal bone. This causes lateral rectus weakness and **diplopia**, which does not necessarily indicate a lesion at the 6th nerve nucleus. * **Option B (Sluggish Pupil/Mydriasis):** Increased ICP can lead to **uncal herniation**. As the temporal lobe uncus herniates through the tentorial notch, it compresses the 3rd cranial nerve (Oculomotor). This results in a dilated, sluggishly reacting pupil (Hutchinson’s pupil) on the side of the herniation, mimicking a primary midbrain or nerve lesion. * **Option C (Homonymous Hemianopia):** This occurs due to the compression of the **Posterior Cerebral Artery (PCA)** against the tentorial edge during herniation, leading to ischemia of the visual cortex. The resulting visual field defect falsely suggests a primary occipital lobe lesion. **Clinical Pearls for NEET-PG:** * **Kernohan’s Notch Phenomenon:** A classic false localizing sign where a mass on one side pushes the contralateral cerebral peduncle against the tentorium, causing **ipsilateral hemiparesis** (instead of the expected contralateral). * **Papilledema:** While a hallmark of raised ICP, it is a *general* sign, not a *false localizing* sign. * **Foster Kennedy Syndrome:** True localizing sign (Anosmia + Ipsilateral optic atrophy + Contralateral papilledema) usually due to frontal lobe tumors.

Q: Which of the following clinical signs is NOT typically observed in a patient with superior oblique palsy?

Ptosis. Superior oblique palsy (4th Cranial Nerve Palsy) is the most common cause of isolated vertical muscle palsy. To understand why **Ptosis** is the correct answer, we must look at the anatomy and clinical presentation of the Trochlear nerve. ### Why Ptosis is NOT observed: Ptosis (drooping of the upper eyelid) is caused by dysfunction of the **Levator Palpebrae Superioris (LPS)** or Müller’s muscle. The LPS is innervated by the **Oculomotor nerve (CN III)**. Superior oblique palsy involves the **Trochlear nerve (CN IV)**, which exclusively supplies the superior oblique muscle. Therefore, ptosis is a feature of CN III palsy or Horner’s syndrome, not CN IV palsy. ### Explanation of Incorrect Options: * **Abnormal head posture:** Patients typically present with a **compensatory head tilt** to the opposite side of the lesion (Bielschowsky's sign) to minimize vertical and torsional diplopia. * **Facial asymmetry:** In congenital cases, long-standing head tilt leads to remodeling of facial bones, resulting in hemi-facial microsomia (the face on the side of the tilt appears smaller). * **Diplopia:** Patients experience **vertical and torsional diplopia**, which worsens on downgaze and adduction (e.g., while reading or walking down stairs). ### High-Yield Clinical Pearls for NEET-PG: * **Park’s Three-Step Test:** The gold standard for diagnosing isolated cyclovertical muscle palsy (like SO palsy). * **Bielschowsky Head Tilt Test:** Forced head tilt to the affected side increases the vertical deviation (hypertropia). * **Most common cause:** Trauma (acquired) or congenital. * **Action of SO:** Primary action is **Incyclotorsion**; secondary is Depression; tertiary is Abduction. (Mnemonic: **SIN** - **S**uperior muscles are **In**vertors).

Q: Centrocaecal scotoma is typically seen in which of the following conditions?

Optic neuritis. **Explanation:** A **centrocaecal scotoma** is a visual field defect that involves both the macular area (fixation point) and the physiological blind spot (optic nerve head). It is a hallmark of diseases affecting the **papillomacular bundle**, the dense collection of nerve fibers that travel from the fovea to the optic disc. **Why Optic Neuritis is correct:** Optic neuritis, particularly the retrobulbar type, frequently involves the central fibers of the optic nerve. This leads to a loss of central vision and the characteristic centrocaecal scotoma. While a central scotoma is more common, the involvement of the papillomacular bundle often extends the defect to the blind spot. **Analysis of Incorrect Options:** * **Wolfram Syndrome (DIDMOAD):** While it causes progressive optic atrophy, the visual field loss is typically peripheral or generalized rather than specifically centrocaecal in the early stages. * **Papilloedema:** In the early stages, the characteristic field defect is an **enlarged blind spot** due to peripapillary retinal edema. Central vision is usually preserved until late stages (secondary optic atrophy). * **CRAO:** This typically presents with sudden, total loss of vision or a dense **altitudinal/generalized defect**. If a cilioretinal artery is present, a small island of central vision may be spared, but it does not produce a centrocaecal scotoma. **Clinical Pearls for NEET-PG:** * **Differential Diagnosis for Centrocaecal Scotoma:** Toxic-nutritional amblyopia (e.g., tobacco-alcohol), Leber’s Hereditary Optic Neuropathy (LHON), and certain drugs (Ethambutol, Isoniazid). * **Central Scotoma:** Seen in Macular Degeneration and Optic Neuritis. * **Bitemporal Hemianopia:** Classic for Optic Chiasm compression (e.g., Pituitary Adenoma). * **Pie in the Sky:** Temporal lobe lesion (Meyer’s loop). * **Pie on the Floor:** Parietal lobe lesion (Baum’s loop).

Question 1

Which of the following is FALSE regarding optic atrophy?

Accepted Answer

Pallor of the disc is due to the degeneration of nerve fibres.

Answer

The disc is chalky white in primary optic atrophy.

Answer

Pallor of the disc cannot be correlated with the amount of visual loss.

Answer

All of the above are false.

Question 2

Aberrant regeneration does not occur after injury to the oculomotor nerve with which one of the following conditions?

Accepted Answer

Ischemia secondary to diabetes

Answer

Trauma

Answer

Tumor compression

Answer

Aneurysm

Question 3

Homonymous hemianopia with macular sparing is seen in:

Accepted Answer

Lesions of the visual cortex

Answer

Lesions of the optic radiations

Answer

Lesions of the lateral geniculate body

Answer

All the above

Question 4

Homonymous hemianopia is seen in a lesion of which of the following?

Accepted Answer

Optic tract, optic radiation, and occipital cortex

Answer

Optic chiasm, optic nerve, and optic radiation

Answer

Optic radiation, occipital cortex, and optic nerve

Answer

Optic nerve, optic tract, and occipital cortex

Question 5

Down and out deviation of the eyeball is due to paralysis of which cranial nerve?

Accepted Answer

Cranial nerve III

Answer

Cranial nerve II

Answer

Cranial nerve VI

Answer

Cranial nerve IX

Question 6

Congenital anomalies of the optic disc include all of the following except?

Accepted Answer

Opaque nerve fibres

Answer

Coloboma

Answer

Drusen

Answer

Hypoplasia

Question 7

Parietal lobe tumors may be associated with which of the following visual field defects?

Accepted Answer

Contralateral lower homonymous quadrantanopia

Answer

Contralateral upper homonymous quadrantanopia

Answer

Both of the above

Answer

None of the above

Question 8

Which of the following is an ocular false localizing sign of raised intracranial pressure?

Accepted Answer

All of the above

Answer

Diplopia due to pressure palsy of the 6th nerve

Answer

Sluggish pupillary reactions and unilateral mydriasis

Answer

Homonymous hemianopia

Question 9

Which of the following clinical signs is NOT typically observed in a patient with superior oblique palsy?

Accepted Answer

Ptosis

Answer

Abnormal head posture

Answer

Facial asymmetry

Answer

Diplopia

Question 10

Centrocaecal scotoma is typically seen in which of the following conditions?

Accepted Answer

Optic neuritis

Answer

Wolfram syndrome

Answer

Papilloedema

Answer

Central retinal artery occlusion (CRAO)

Neuro-Ophthalmology — MCQs

Neuro-Ophthalmology — MCQs

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