Neuro-Ophthalmology Practice Questions

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

Abnormal electroretinogram. ***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.

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

Marcus Gunn pupil. ***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.

Q: Foster Kennedy syndrome is

I/L Optic atrophy C/L papilloedema. ***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.

Q: Arcuate field defect akin to glaucoma is seen in?

Optic nerve lesion. ***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.

Q: Which of the following is NOT typically seen in 3rd nerve palsy?

Loss of abduction. ***Loss of abduction*** - The **oculomotor nerve (CN III)** controls adduction, elevation, and depression of the eye, but **not abduction**. [2] - **Abduction** is primarily controlled by the **abducens nerve (CN VI)**, so its loss would indicate a CN VI palsy. *Mydriasis* - The **oculomotor nerve (CN III)** innervates the **parasympathetic fibers** to the pupillary constrictor muscles. [3] - Palsy of these fibers leads to unopposed action of the sympathetic dilator muscles, causing **mydriasis (pupil dilation)**. [4] *Ptosis* - The **oculomotor nerve (CN III)** innervates the **levator palpebrae superioris muscle**, which lifts the eyelid. - Dysfunction of this nerve leads to **ptosis (drooping of the eyelid)**. [1] *Loss of light reflex* - The **efferent pathway** for the **pupillary light reflex** travels via the **oculomotor nerve (CN III)** to constrict the pupil. [3] - A 3rd nerve palsy, particularly affecting the parasympathetic fibers, **impairs pupillary constriction**, resulting in a loss of the direct and consensual light reflex in the affected eye. [4]

Q: Most common cause of bilateral optic atrophy is:

Nutritional deficiency (B12/folate). ***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.

Q: In which condition is the swinging light test positive?

Optic neuritis. ***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.

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

Contralateral homonymous hemianopsia. ***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.

Q: Keyhole-shaped visual field defect is seen in a lesion involving which of the following regions?

Lesion of the optic disk. ***Lesion of the optic disk*** - A **keyhole-shaped visual field defect** is a **pathognomonic sign** of **optic disc lesions**, particularly in **glaucomatous optic neuropathy**. - This characteristic defect occurs due to damage to **retinal nerve fiber bundles** as they converge at the optic disc, respecting the **horizontal raphé**. - Arcuate scotomas (superior and inferior) can coalesce around the point of fixation, creating the distinctive **keyhole or dumbbell shape**. - The pattern reflects the anatomical organization of nerve fibers entering the optic nerve head. *Lesion of the lateral geniculate body* - Lesions of the **lateral geniculate body (LGB)** typically cause **incongruous homonymous hemianopias** or **quadrantanopias**, not keyhole defects. - The LGB has retinotopic organization with six layers, and partial lesions cause visual field defects affecting corresponding areas in both eyes. - Vascular lesions (from lateral choroidal artery branches) can cause sector-shaped or wedge-shaped defects, but not keyhole patterns. *Lesion of the optic chiasma* - A lesion of the optic chiasma typically leads to **bitemporal hemianopia**, where the temporal visual fields of both eyes are affected, usually due to compression from a **pituitary tumor**. - This is characterized by loss of vision in the outer halves of the visual field for both eyes, which is distinct from a keyhole defect. - The crossing nasal fibers are affected, resulting in bilateral temporal field loss. *Lesion of the occipital lobe* - Lesions in the occipital lobe, specifically the **primary visual cortex (V1)**, generally cause **homonymous hemianopia** or **quadrantanopia** respecting the vertical midline. - This means the same side of the visual field is affected in both eyes, and **macular sparing** may be present due to dual vascular supply. - Occipital lobe defects are typically congruous (identical in both eyes) and do not produce keyhole-shaped patterns.

Q: Third nerve palsy causes all of the following except:

Miosis. ***Miosis*** - A complete third nerve palsy typically presents with a **dilated pupil (mydriasis)** due to unopposed sympathetic innervation, not miosis [1]. - **Miosis** (pupil constriction) would occur if the parasympathetic fibers of the third nerve were overactive or due to sympathetic denervation (Horner's syndrome) [2]. *Ptosis* - The **levator palpebrae superioris muscle**, responsible for eyelid elevation, is innervated by the oculomotor (third) nerve [2]. - Damage to this nerve paralyzes the muscle, leading to **drooping of the eyelid (ptosis)** [1]. *Outward eye movement* - The oculomotor nerve innervates most extraocular muscles, including the medial, superior, and inferior rectus, and the inferior oblique. - When these muscles are paralyzed, the unopposed action of the **lateral rectus** (innervated by CN VI) causes the eye to deviate **laterally (outward)** [1]. *Diplopia* - Paralysis of the extraocular muscles innervated by the third nerve leads to **misalignment of the eyes** [1]. - This misalignment prevents the brain from fusing the images from both eyes, resulting in **double vision (diplopia)** [1].

Question 1

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

Accepted Answer

Abnormal electroretinogram

Answer

Decreased pupillary reflex

Answer

Decreased visual acuity

Answer

Abnormal visual evoked potentials (VEP)

Question 2

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

Accepted Answer

Marcus Gunn pupil

Answer

Efferent pathway defect

Answer

Cerebral lesion

Answer

Total afferent pupillary defect

Question 3

Foster Kennedy syndrome is

Accepted Answer

I/L Optic atrophy C/L papilloedema

Answer

I/L Optic atrophy with papilloedema

Answer

I/L Papilloedema with C/L optic atrophy

Answer

I/L Papilloedema C/L papilitis

Question 4

Arcuate field defect akin to glaucoma is seen in?

Accepted Answer

Optic nerve lesion

Answer

Pituitary adenoma

Answer

Posterior cerebral artery infarct

Answer

None of the options

Question 5

Which of the following is NOT typically seen in 3rd nerve palsy?

Accepted Answer

Loss of abduction

Answer

Mydriasis

Answer

Ptosis

Answer

Loss of light reflex

Question 6

Most common cause of bilateral optic atrophy is:

Accepted Answer

Nutritional deficiency (B12/folate)

Answer

Intracranial tumor

Answer

Hereditary optic neuropathy

Answer

Toxic optic neuropathy

Question 7

In which condition is the swinging light test positive?

Accepted Answer

Optic neuritis

Answer

Conjunctivitis

Answer

Glaucoma

Answer

Keratoconus

Question 8

What visual disturbance is caused by an optic tract lesion?

Accepted Answer

Contralateral homonymous hemianopsia

Answer

Marcus Gunn pupil

Answer

Bilateral blindness

Answer

Ipsilateral homonymous hemianopsia

Question 9

Keyhole-shaped visual field defect is seen in a lesion involving which of the following regions?

Accepted Answer

Lesion of the optic disk

Answer

Lesion of the lateral geniculate body

Answer

Lesion of the optic chiasma

Answer

Lesion of the occipital lobe

Question 10

Third nerve palsy causes all of the following except:

Accepted Answer

Miosis

Answer

Outward eye movement

Answer

Diplopia

Answer

Ptosis

Neuro-Ophthalmology — MCQs

Neuro-Ophthalmology — MCQs

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