Neuro-Ophthalmology — MCQs

Neuro-Ophthalmology Indian Medical PG Practice Questions and MCQs

Question 381: Which of the following is NOT a clinical feature of Leber optic neuropathy?

A. It is an example of gradual painless visual loss (Correct Answer)
B. No leak of dye is observed in fluorescein angiography
C. Seen in the 2nd or 3rd decade of life
D. It is inherited through mitochondrial DNA

Explanation: ***Correct Answer: It is an example of gradual painless visual loss*** - Leber Hereditary Optic Neuropathy (LHON) typically presents with **acute or subacute painless central vision loss**, NOT gradual loss. - The vision loss occurs **rapidly over days to weeks**, usually affecting one eye first, followed by the other eye within weeks to months. - This makes Option A the correct answer to this "NOT" question, as gradual onset is NOT characteristic of LHON. *Incorrect Option: No leak of dye is observed in fluorescein angiography* - This is a **true clinical feature** of LHON and therefore not the correct answer to this "NOT" question. - **Fluorescein angiography** in LHON typically shows **no leakage**, which helps differentiate it from inflammatory or ischemic optic neuropathies. - The absence of leakage reflects that the primary pathology is mitochondrial dysfunction affecting retinal ganglion cells, not vascular inflammation or blood-retinal barrier breakdown. *Incorrect Option: Seen in the 2nd or 3rd decade of life* - This is a **true clinical feature** of LHON and therefore not the correct answer. - LHON most commonly manifests in **young adulthood**, with peak onset between **15-35 years** (2nd to 3rd decade). - Males are affected more frequently than females (approximately 80-90% of cases). *Incorrect Option: It is inherited through mitochondrial DNA* - This is a **true clinical feature** of LHON and therefore not the correct answer. - LHON is caused by mutations in **mitochondrial DNA (mtDNA)**, most commonly at positions 11778, 3460, and 14484. - Shows **maternal inheritance** - passed from mother to all children, but only daughters transmit to subsequent generations.

Question 382: Which of the following statements is MOST likely false regarding optic neuritis?

A. Abnormal electroretinogram (Correct Answer)
B. Decreased pupillary reflex
C. Decreased visual acuity
D. Abnormal visual evoked potentials (VEP)

Explanation: ***Abnormal electroretinogram*** - Optic neuritis primarily affects the **optic nerve**, which is responsible for transmitting visual information from the retina to the brain. - The **electroretinogram (ERG)** measures the electrical activity of the **retina** in response to light, which is usually normal in optic neuritis as the retina itself is not the primary site of pathology. *Decreased pupillary reflex* - Optic neuritis often causes a **relative afferent pupillary defect (RAPD)**, where the affected eye's pupil dilates instead of constricting when light is swung from the unaffected to the affected eye. - This indicates a decrease in the afferent nerve signal transmission due to damage to the optic nerve. *Decreased visual acuity* - A hallmark symptom of optic neuritis is **acute vision loss**, which can range from mild blurring to severe vision impairment. - This vision loss is typically unilateral and can progress over several days. *Abnormal visual evoked potentials (VEP)* - **VEPs** measure the electrical activity of the brain in response to visual stimuli, assessing the integrity of the optic nerve and visual pathways. - In optic neuritis, the demyelination and damage to the optic nerve cause a **slowing of nerve conduction**, leading to increased latency and reduced amplitude in VEPs.

Question 383: Arcuate field defect akin to glaucoma is seen in?

A. Optic nerve lesion (Correct Answer)
B. Pituitary adenoma
C. Posterior cerebral artery infarct
D. None of the options

Explanation: ***Optic nerve lesion*** - An **arcuate field defect** is a specific pattern of visual field loss that follows the course of nerve fibers in the retina and is characteristic of **optic nerve damage**, similar to what is seen in glaucoma. - This type of defect is due to damage to the **bundle of retinal nerve fibers** that arch above or below the macula, often causing a scotoma (blind spot) that respects the horizontal meridian. - Common causes include **anterior ischemic optic neuropathy (AION)**, **optic neuritis**, and other optic nerve pathologies that affect the nerve fiber layer. *Pituitary adenoma* - A pituitary adenoma typically causes a **bitemporal hemianopsia** due to compression of the optic chiasm. - This visual field defect involves the lateral halves of both visual fields, which is different from an arcuate defect. *Posterior cerebral artery infarct* - An infarct in the posterior cerebral artery typically leads to a **homonymous hemianopsia** (loss of half of the visual field on the same side in both eyes) or a quadrantanopsia. - This type of defect results from damage to the **visual cortex** or optic radiations, not the optic nerve itself in a glaucoma-like pattern. *None of the options* - This is incorrect because **optic nerve lesion** is a valid and correct answer. - Optic nerve pathologies are well-established causes of arcuate field defects similar to those seen in glaucoma.

Question 384: What is the condition characterized by a relative afferent pupillary defect?

A. Efferent pathway defect
B. Cerebral lesion
C. Total afferent pupillary defect
D. Marcus Gunn pupil (Correct Answer)

Explanation: ***Marcus Gunn pupil, a defect in the afferent pathway of the eye*** - A **Marcus Gunn pupil**, also known as a **relative afferent pupillary defect (RAPD)**, occurs due to a lesion or dysfunction in the **afferent (sensory) pathway** of one eye. - This results in an asymmetric response to light, where the pupil of the affected eye appears to dilate paradoxically when light is swung from the unaffected to the affected eye during the **swinging flashlight test**. *Efferent pathway defect* - An **efferent pathway defect** (e.g., in the oculomotor nerve, CN III) would cause a **fixed, dilated pupil** with impaired direct and consensual light reflexes, rather than an RAPD. - Such a defect would typically affect the motor response of the pupil, causing it to be unable to constrict. *Cerebral lesion* - While certain cerebral lesions can affect pupillary responses, a **relative afferent pupillary defect** specifically points to an issue in the direct sensory input from the retina to the brainstem. - Large **cerebral lesions** are more likely to cause other neurological signs or abnormalities in the motor control of the eye. *Total afferent pupillary defect* - A **total afferent pupillary defect**, often seen in **amaurotic pupil** (blind eye without light perception), would result in no direct or consensual light response in the affected eye. - In a RAPD, there is still some, albeit reduced, response to light, making it a **relative** defect rather than a total absence of afferent signaling.

Question 385: Foster Kennedy syndrome is

A. I/L Optic atrophy C/L papilloedema (Correct Answer)
B. I/L Optic atrophy with papilloedema
C. I/L Papilloedema with C/L optic atrophy
D. I/L Papilloedema C/L papilitis

Explanation: ***I/L Optic atrophy C/L papilloedema*** - **Foster Kennedy syndrome** is characterized by the combination of **ipsilateral optic atrophy** and **contralateral papilledema**. - This constellation of signs is typically caused by a **frontal lobe mass** (e.g., meningioma or glioma) that directly compresses the ipsilateral optic nerve, leading to atrophy, while also causing increased **intracranial pressure** that manifests as papilledema in the contralateral eye. *I/L Papilloedema with C/L optic atrophy* - This describes the reverse of Foster Kennedy syndrome and is not a recognized clinical entity associated with a specific pathological process. - Papilledema is due to **increased intracranial pressure**, and optic atrophy is due to nerve damage; these would typically manifest in specific patterns related to the location and timing of the insult. *I/L Optic atrophy with papilloedema* - This option describes both conditions occurring in the **same (ipsilateral) eye**, which contradicts the characteristic presentation of Foster Kennedy syndrome. - While an eye can have both optic atrophy and papilledema (e.g., resolving papilledema or an underlying condition), it is not the defining feature of Foster Kennedy syndrome. *UL Papilloedema C/L papilitis* - This option mentions **papilledema** in one eye (unilateral or ipsilateral is implied) and **papillitis** in the other. - **Papillitis** is an inflammatory condition of the optic nerve head, while papilledema is due to increased intracranial pressure. This combination is not characteristic of Foster Kennedy syndrome, which specifically involves atrophy and papilledema due to a mass lesion.

Question 386: Most common cause of bilateral optic atrophy is:

A. Intracranial tumor
B. Nutritional deficiency (B12/folate) (Correct Answer)
C. Hereditary optic neuropathy
D. Toxic optic neuropathy

Explanation: ***Nutritional deficiency (B12/folate)*** - **Nutritional optic neuropathy** due to deficiencies in B vitamins (especially B12, thiamine) and folate is a common cause of bilateral optic atrophy, particularly in **developing countries** and in populations with **malnutrition or chronic alcoholism**. - These deficiencies impair the **metabolism of retinal ganglion cells** and their axons, leading to symmetric bilateral optic nerve degeneration. - The condition is often **reversible in early stages** with appropriate supplementation. - **Note:** The "most common" cause varies by geographic location, population, and clinical setting. *Hereditary optic neuropathy* - **Leber's hereditary optic neuropathy (LHON)** and **autosomal dominant optic atrophy (ADOA)** are major causes of bilateral optic atrophy, especially in **younger patients**. - LHON typically presents in young males (15-35 years) with **sequential bilateral visual loss**. - These are among the **most common inherited optic neuropathies** and should always be considered in bilateral cases. *Intracranial tumor* - Intracranial tumors typically cause **unilateral optic atrophy** due to direct compression of one optic nerve. - **Bilateral optic atrophy** can occur with **chiasmal or suprasellar tumors** (pituitary adenomas, craniopharyngiomas) but is less common. - Usually presents with **visual field defects** (bitemporal hemianopia) before significant atrophy develops. *Toxic optic neuropathy* - **Toxic optic neuropathies** result from exposure to substances such as **methanol, ethambutol, tobacco-alcohol amblyopia**, or isoniazid. - Can cause bilateral symmetric optic atrophy but are **exposure-dependent** and less prevalent in general population. - **Tobacco-alcohol amblyopia** may overlap with nutritional deficiency.

Question 387: What visual disturbance is caused by an optic tract lesion?

A. Marcus Gunn pupil
B. Bilateral blindness
C. Contralateral homonymous hemianopsia (Correct Answer)
D. Ipsilateral homonymous hemianopsia

Explanation: ***Contralateral homonymous hemianopsia*** - An **optic tract lesion** interrupts the nerve fibers originating from the contralateral nasal retina and the ipsilateral temporal retina, leading to **vision loss in the contralateral visual field** of both eyes. - This results in a defect where the patient cannot see objects on the **opposite side** of the body from the lesion. *Marcus Gunn pupil* - A **Marcus Gunn pupil**, also known as an **afferent pupillary defect**, indicates asymmetric disease of the **retina** or **optic nerve**, not specifically the optic tract. - It is characterized by paradoxical dilation of the affected pupil when light is swung from the unaffected to the affected eye. *Bilateral blindness* - **Bilateral blindness** typically results from severe damage to both **optic nerves**, the **optic chiasm**, or extensive bilateral lesions in the visual cortex. - An optic tract lesion affects only one side of the visual pathway posterior to the chiasm, thus not causing complete bilateral vision loss. *Ipsilateral homonymous hemianopsia* - **Ipsilateral homonymous hemianopsia** is not a standard neurological visual field defect. Visual field defects are usually described relative to the lesion side as contralateral or ipsilateral based on the specific anatomical location. - An optic tract lesion always produces a **contralateral homonymous hemianopsia** because optic tract fibers cross at the optic chiasm.

Question 388: In which condition is the swinging light test positive?

A. Conjunctivitis
B. Glaucoma
C. Keratoconus
D. Optic neuritis (Correct Answer)

Explanation: ***Optic neuritis*** - The swinging light test (also known as the **Marcus Gunn pupil** or relative afferent pupillary defect, RAPD) is positive when there is a significant **asymmetry in the afferent visual pathway** between the two eyes. - In optic neuritis, the **optic nerve** is inflamed and demyelinated, impairing the transmission of light signals to the brain, which leads to a paradoxical pupillary dilation when the light is swung from the unaffected to the affected eye. *Conjunctivitis* - This is an **inflammation of the conjunctiva**, the membrane lining the eyelid and sclera, which primarily affects the ocular surface. - It does not involve the optic nerve or afferent pupillary pathways, so the swinging light test would be **negative**. *Glaucoma* - Glaucoma is a condition characterized by **progressive optic nerve damage**, often associated with elevated intraocular pressure, leading to peripheral vision loss. - While it causes optic neuropathy, a positive swinging light test is typically seen only in **severe, asymmetric cases** and is not its primary diagnostic feature. *Keratoconus* - This is a non-inflammatory eye condition in which the normally round dome-shaped cornea **thins and bulges outward into a cone-like shape**. - It affects the **cornea's shape and vision quality**, but not the optic nerve or the afferent pupillary reflex pathway, thus the swinging light test would be negative.

Question 389: All of the following signs may be appreciated in a patient with early papilloedema, except:

A. Obscuration of superior, inferior and nasal disc margins
B. Absence of spontaneous venous pulsation
C. Obliteration of physiological cup of the optic disc (Correct Answer)
D. Mild hyperaemia of the disc

Explanation: ***Obliteration of physiological cup of the optic disc*** - **Obliteration of the physiological cup** occurs in **moderate to severe papilloedema**, NOT in early stages - In **early papilloedema**, the physiological cup is typically **preserved or only minimally affected** - As disc swelling progresses over time, the cup becomes filled in and eventually obliterated - Since this question asks about **early papilloedema**, obliteration of the cup is NOT yet appreciated, making this the correct answer *Mild hyperaemia of the disc* - **Mild hyperaemia** (redness) of the optic disc is an early sign of papilloedema - Results from increased blood flow and capillary dilation due to venous congestion - Often one of the first visible changes in early papilloedema *Obscuration of superior, inferior and nasal disc margins* - **Blurring of disc margins** is a hallmark early sign of papilloedema - Typically begins at the **nasal margin** (most sensitive), followed by superior and inferior margins - The temporal margin is usually the last to be affected - Caused by axoplasmic stasis and peripapillary retinal edema *Absence of spontaneous venous pulsation* - The **absence of spontaneous venous pulsation** (SVP) is one of the earliest signs of elevated intracranial pressure - Normally present in approximately 80-90% of healthy individuals - Loss of SVP indicates elevated pressure in the optic nerve sheath transmitted from increased ICP - While not 100% specific, its absence in someone who previously had SVP is highly suggestive of early papilloedema

Question 390: Anterior ischemic optic neuropathy is characterized by:

A. Centrocaecal scotoma
B. Altitudinal hemianopia (Correct Answer)
C. Ring scotoma
D. Increased blood supply

Explanation: ***Altitudinal hemianopia*** - **Anterior ischemic optic neuropathy (AION)** typically causes **sudden, painless vision loss** in one eye, often presenting as **altitudinal visual field defects**. - This pattern results from **ischemia** to the **optic nerve head**, affecting the superior or inferior retinal nerve fiber layers. *Centrocaecal scotoma* - A **centrocaecal scotoma** is a visual field defect that encompasses both the **central vision** and the **blind spot**. - This pattern is more characteristic of **toxic or nutritional optic neuropathies**, not typically AION. *Ring scotoma* - A **ring scotoma** is a circular defect around the **central visual field**, sparing the fovea. - This type of scotoma is commonly seen in diseases like **retinitis pigmentosa**, which affects peripheral and mid-peripheral retina rather than the optic nerve head as seen in AION. *Increased blood supply* - **Anterior ischemic optic neuropathy** is fundamentally caused by a **reduced or insufficient blood supply** to the optic nerve head, leading to **ischemia and infarction**. - Increased blood supply would be beneficial and would not cause the vision loss characteristic of AION.

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

Practice Questions

Neuro-ophthalmic Manifestations of Intracranial Lesions

Practice Questions

Functional Visual Disorders

Practice Questions

Migraine and the Eye

Practice Questions

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