Internal Medicine
2 questionsAnisocoria in Horner's syndrome is due to
Macular sparing is associated with lesions in:
NEET-PG 2015 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 881: Anisocoria in Horner's syndrome is due to
- A. Disruption of the oculosympathetic pathway (Correct Answer)
- B. Disruption of the oculoparasympathetic pathway
- C. Disruption of the oculomotor nerve
- D. Disruption of the abducens nerve
Explanation: ***Disruption of the oculosympathetic pathway*** - Horner's syndrome results from a lesion interrupting the **oculosympathetic pathway**, leading to classic symptoms of **miosis**, **ptosis**, and **anhidrosis** [1]. - The **miosis** (constricted pupil) specifically arises from the unopposed action of the **parasympathetic innervation** to the pupil dilatory muscles when sympathetic innervation is disrupted. *Disruption of the oculoparasympathetic pathway* - Disruption of the oculoparasympathetic pathway would result in **mydriasis** (dilated pupil), not miosis as seen in Horner's syndrome [2]. - This pathway is responsible for stimulating the **pupillary constrictor muscles**, and its disruption would lead to an inability to constrict the pupil [3]. *Disruption of the oculomotor nerve* - The **oculomotor nerve** (CN III) carries parasympathetic fibers to the eye, and its disruption typically causes a **fixed and dilated pupil** due to unopposed sympathetic action [3]. - Oculomotor nerve palsy also presents with **ptosis** and **down-and-out deviation** of the eye, which are not characteristic of isolated Horner's syndrome [1], [4]. *Disruption of the abducens nerve* - The **abducens nerve** (CN VI) solely innervates the **lateral rectus muscle**, responsible for abducting the eye. - Disruption of the abducens nerve causes **diplopia** and an inability to abduct the affected eye, with no direct impact on pupil size.
Question 882: Macular sparing is associated with lesions in:
- A. Lesions in the optic nerve
- B. Lesions in the lateral geniculate body
- C. Lesions in the occipital cortex (Correct Answer)
- D. Lesions in the optic chiasma
Explanation: ***Lesions in the occipital cortex*** - **Macular sparing** occurs when the central visual field (macula) is preserved despite damage to the occipital cortex, often due to its dual blood supply from the **middle cerebral artery** and the **posterior cerebral artery**. [2] - This phenomenon typically results from a **vascular lesion** in the occipital lobe, leading to a **homonymous hemianopia** with a distinct sparing of the foveal region. [2], [3] *Lesions in the optic nerve* - Lesions in the optic nerve cause **monocular vision loss** or central scotomas, rather than the homonymous visual field defects associated with macular sparing. [2] - Damage here affects the visual pathway **before** the optic chiasm, impacting the entire visual input from one eye. [2] *Lesions in the lateral geniculate body* - Lesions in the **lateral geniculate body (LGB)** produce **contralateral homonymous hemianopia** or quadrantanopia, but typically **do not exhibit macular sparing** as consistently as cortical lesions. - The LGB processes visual information from both eyes before relaying it to the visual cortex. [1] *Lesions in the optic chiasma* - Lesions in the **optic chiasma** classically cause **bitemporal hemianopia**, affecting the temporal visual fields of both eyes. [2] - This type of visual field defect is distinct from the homonymous defects seen with macular sparing, as it results from damage to the **crossing nasal fibers**. [2]
Ophthalmology
8 questionsWhat is the typical appearance of a subhyaloid hemorrhage in the eye?
Most common age related change in vitreous?
Muscae volitantes is seen in?
Which of the following statements is MOST likely false regarding optic neuritis?
The most common type of strabismus seen in myopes is?
Dalrymple's sign of ocular Graves' disease refers to which of the following?
D Shaped pupil is seen in which condition?
In which of the following conditions does Berlin's edema occur?
NEET-PG 2015 - Ophthalmology NEET-PG Practice Questions and MCQs
Question 881: What is the typical appearance of a subhyaloid hemorrhage in the eye?
- A. Boat shaped (Correct Answer)
- B. Crescent shaped
- C. Round
- D. Flame shaped
Explanation: ***Boat shaped*** - A subhyaloid hemorrhage is located beneath the **hyaloid membrane** (the posterior vitreous cortex), which is attached to the retina. - The collected blood often assumes a **dependent, gravity-influenced shape**, appearing flat on top and curved underneath, resembling a boat. *Crescent shaped* - This shape is not characteristic of a typical subhyaloid hemorrhage; it might be seen in other types of hemorrhages or detachment patterns. - **Crescentic shapes** are more commonly associated with certain types of **retinal detachments** or tears where fluid accumulation takes on a curved boundary. *Round* - While hemorrhages can be round, a subhyaloid hemorrhage typically spreads out due to gravity within the confined space, resulting in a more distinct shape. - A **perfectly round hemorrhage** is less common in the subhyaloid space as blood tends to layer out rather than remain as a sphere. *Flame shaped* - **Flame-shaped hemorrhages** are typically found in the **nerve fiber layer** due to the orientation of nerve fibers. - These hemorrhages are shallower and follow the linear arrangement of nerve fibers, unlike the larger, more globular subhyaloid bleeds.
Question 882: Most common age related change in vitreous?
- A. Anterior vitreous detachment
- B. Vitreous hemorrhage
- C. Vitritis
- D. Posterior vitreous detachment (PVD) (Correct Answer)
Explanation: ***Posterior vitreous detachment (PVD)*** - As we age, the **vitreous body** undergoes liquefaction and shrinkage, leading to its separation from the **retina**, most commonly posteriorly. - This is a very common and usually benign age-related phenomenon, often presenting with **floaters** and **flashes of light**. *Anterior vitreous detachment* - **Anterior vitreous detachment** is much less common than PVD and not typically considered the most frequent age-related change. - It often occurs secondary to **trauma** or specific surgical procedures rather than spontaneous aging alone. *Vitreous hemorrhage* - **Vitreous hemorrhage** is a pathological condition involving bleeding into the vitreous humor, often due to **diabetic retinopathy**, retinal tears, or trauma. - It is not a normal age-related change but a complication of underlying disease. *Vitritis* - **Vitritis** refers to inflammation of the vitreous humor, commonly associated with **uveitis** or infections. - It is an inflammatory disease process, not a physiological age-related degeneration of the vitreous.
Question 883: Muscae volitantes is seen in?
- A. Vitreous detachment (Correct Answer)
- B. Vitreous Hemorrhage
- C. Remains of primitive hyaloid vasculature
- D. Eale's disease
Explanation: ***Vitreous detachment*** - **Muscae volitantes** (Latin for "flying flies") is the classical term for **vitreous floaters** - **Posterior vitreous detachment (PVD)** is the **most common cause** of muscae volitantes - PVD occurs due to **vitreous liquefaction** and **vitreoretinal separation**, causing **collagen fibers and cellular debris** to cast shadows on the retina - These floaters are typically described as **spots, cobwebs, or threads** that move with eye movement - PVD is extremely common, particularly **after age 50-60 years**, and in **myopic patients** *Remains of primitive hyaloid vasculature* - **Hyaloid remnants** (such as **Mittendorf's dot** or **Bergmeister's papilla**) are **congenital developmental anomalies** - While these can occasionally be visible as small opacities, they are **not the classical cause** of muscae volitantes - These are typically **stationary** rather than "floating" as the term implies *Vitreous Hemorrhage* - Causes **sudden onset** of numerous floaters, often described as **"shower of red blood cells"** or dense black spots - Associated with **significant vision loss** and requires urgent evaluation - Not the benign, chronic floaters typical of muscae volitantes *Eale's disease* - **Peripheral retinal vasculitis** causing **recurrent vitreous hemorrhages** - Floaters occur secondary to **hemorrhage**, not the primary pathology of muscae volitantes - Presents with **recurrent episodes** and **vision loss**, not isolated benign floaters
Question 884: 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 885: The most common type of strabismus seen in myopes is?
- A. Intermittent Exotropia (Correct Answer)
- B. Intermittent Esotropia
- C. Esotropia Hypotropia complex
- D. Exotropia Hypotropia complex
Explanation: ***Intermittent Exotropia*** - Myopes often employ less **accommodative effort** for near tasks, leading to reduced **accommodative convergence** and an increased tendency for the eyes to drift outwards. - This outward deviation, or **exotropia**, is frequently intermittent, especially during fatigue or inattention. *Intermittent Esotropia* - **Esotropia** is an inward turn of the eye and is typically associated with **hyperopia** due to excessive accommodative effort leading to increased accommodative convergence. - While it can be intermittent, it is not the most common form of strabismus in myopic individuals. *Esotropia hypotropia complex* - This complex involves both an inward deviation (**esotropia**) and a downward deviation (**hypotropia**). - It is not typically seen in healthy myopes and would suggest other underlying **neurological** or **structural abnormalities**. *Exotropia Hypotropia complex* - While **exotropia** can be common in myopes, the additional presence of **hypotropia** (downward deviation) suggests a more complex strabismic picture. - This combination is not the most frequent strabismus seen in uncomplicated myopia and may indicate **cranial nerve palsies** or **orbital anomalies**.
Question 886: Dalrymple's sign of ocular Graves' disease refers to which of the following?
- A. Retraction of the upper lid (Correct Answer)
- B. Lid lag
- C. Proptosis
- D. Convergence insufficiency
Explanation: ***Retraction of the upper lid*** - **Dalrymple's sign** specifically refers to the **wide-eyed stare** seen in **Graves' ophthalmopathy** due to **retraction of the upper eyelid**. - This symptom is caused by sympathetic overactivity of the **levator palpebrae superioris muscle**. *Lid lag* - **Lid lag (Graefe's sign)** is a different ocular sign where the **upper eyelid lags behind the globe** on downward gaze. - While also seen in **Graves' disease**, it is distinct from constant upper lid retraction. *Proptosis* - **Proptosis**, or **exophthalmos**, is the **forward protrusion of the eyeball** from the orbit. - This is a common feature of **Graves' ophthalmopathy**, but it is not what Dalrymple's sign refers to. *Convergence insufficiency* - **Convergence insufficiency (Moebius sign)** refers to the **inability to maintain convergence** during near vision. - While this can occur in **thyroid eye disease**, it is not Dalrymple's sign.
Question 887: D Shaped pupil is seen in which condition?
- A. Anterior synechiae
- B. Anterior Uveitis
- C. Iridodialysis (Correct Answer)
- D. Iridodonesis
Explanation: ***Iridodialysis*** - **Iridodialysis** is a disinsertion or separation of the iris from its root at the ciliary body. - This separation creates a D-shaped or keyhole pupil, as the detached portion of the iris no longer contributes to the circular pupillary margin. *Anterior Uveitis* - **Anterior uveitis** is inflammation of the iris and ciliary body, primarily causing miosis (constricted pupil), not a D-shaped pupil. - It can lead to posterior synechiae, resulting in an irregular, but not typically D-shaped, pupil. *Anterior synechiae* - **Anterior synechiae** involve adhesions between the iris and the corneal endothelium or trabecular meshwork. - While they can cause an irregular pupil shape, they typically pull the iris towards the cornea rather than creating a D-shape from iris root disinsertion. *Iridodonesis* - **Iridodonesis** refers to tremors or wobbling of the iris, often seen in cases of aphakia or subluxated lenses, due to lack of support. - It describes a movement disorder of the iris rather than an abnormal, fixed pupil shape like a D-shaped pupil.
Question 888: In which of the following conditions does Berlin's edema occur?
- A. Open angle glaucoma
- B. After cataract surgery
- C. After concussional trauma (Correct Answer)
- D. Diabetic retinopathy
Explanation: ***After concussional trauma*** - **Berlin's edema**, also known as **commotio retinae**, is a form of **retinal edema** that occurs following **blunt trauma** to the eye. - It results from the disruption of the **photoreceptor outer segments** and retinal pigment epithelium, leading to a **dull, gray-white appearance** of the retina. *Open angle glaucoma* - Characterized by **progressive optic nerve damage** and visual field loss, typically due to elevated intraocular pressure, without retinal edema. - The primary pathology involves the **trabecular meshwork**, not direct retinal swelling. *After cataract surgery* - A common complication is **cystoid macular edema** (Irvine-Gass syndrome), which affects the macula and can cause blurred vision. - This is distinct from Berlin's edema, as it is a **post-surgical inflammatory response**, not a direct traumatic injury. *Diabetic retinopathy* - Involves various retinal changes due to diabetes, such as **microaneurysms**, hemorrhages, and **macular edema** from leaky vessels. - It is a **metabolic and vascular disease**, not a direct consequence of acute ocular trauma.