NEET-PG 2012 Practice Questions

Q: What is the most common protozoan associated with keratitis?

Acanthamoeba. ***Acanthamoeba*** - **Acanthamoeba keratitis** is a serious and painful infection of the eye's cornea, most commonly associated with **contact lens wearers** who do not properly disinfect their lenses. - The organism is a **free-living protozoan** found in soil and water. *Plasmodium* - **Plasmodium** species are the causative agents of **malaria**, a disease that primarily affects **red blood cells** and the liver. - While it can manifest with ocular symptoms like **retinopathy**, it does not typically cause **keratitis**. *Toxoplasma* - **Toxoplasma gondii** causes **toxoplasmosis**, an infection that can lead to **chorioretinitis** (inflammation of the retina and choroid), especially in immunocompromised individuals or congenitally infected infants. - It does not directly cause **keratitis** as its primary ocular manifestation. *Entamoeba histolytica* - **Entamoeba histolytica** is the protozoan responsible for **amebiasis**, particularly **amoebic dysentery** and **liver abscesses**. - Ocular involvement with *Entamoeba histolytica* is extremely rare and typically involves **metastatic lesions** to the orbit or eyelids, not directly primary keratitis.

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: Which muscle is the earliest to be involved in thyroid ophthalmopathy?

Inferior Rectus (IR). ***Inferior Rectus (IR)*** - The **inferior rectus muscle** is most commonly and earliest affected in **thyroid ophthalmopathy** due to its anatomical location and muscle fiber type, making it highly susceptible to inflammation and edema. - Involvement of the inferior rectus leads to restricted **upward gaze** and **diplopia**, which are characteristic early symptoms of thyroid eye disease. *Medial Rectus (MR)* - While the **medial rectus** is often involved in thyroid ophthalmopathy, it is typically affected *after* the inferior rectus. - Dysfunction of the medial rectus manifests as difficulty with **adduction** (moving the eye inwards). *Superior Rectus (SR)* - The **superior rectus** is less frequently and usually later involved compared to the inferior and medial rectus muscles. - Its involvement typically causes restricted **downward gaze**. *Lateral Rectus (LR)* - The **lateral rectus** muscle is the *least common* ocular muscle to be affected in thyroid ophthalmopathy. - When affected, it primarily causes difficulty with **abduction** (moving the eye outwards).

Q: What is the treatment of choice for amblyopia?

Occlusion therapy. ***Occlusion therapy*** - **Occlusion therapy** involves patching the stronger eye to force the weaker, amblyopic eye to work harder, thereby strengthening its neural connections. - This treatment is most effective when initiated during the **critical period of visual development** in childhood. *Corrective spectacles* - While essential for addressing **refractive errors** that may contribute to amblyopia, spectacles alone are often insufficient to resolve the amblyopia. - Spectacles primarily optimize the image quality on the retina, but don't directly address the **cortical suppression** of the amblyopic eye. *Surgical intervention* - **Surgical intervention** is typically reserved for correcting structural issues like **strabismus** (misalignment of the eyes) that contribute to amblyopia. - Surgery for strabismus aims to align the eyes, which can then be followed by occlusion therapy or other treatments to address the functional amblyopia. *Convergent exercises for vision therapy* - **Vision therapy exercises**, including convergent exercises, may be used as an adjunct to occlusion therapy or in cases of **convergence insufficiency**. - However, they are not the primary or solitary treatment of choice for amblyopia, which requires direct stimulation of the amblyopic eye.

Q: Most common orbital tumor has its origin from?

Blood vessels. ***Blood vessels*** - The most common orbital tumor in childhood is a **capillary hemangioma**, which originates from blood vessels. - In adults, the most common primary orbital tumor is an orbital varix, also a **vascular lesion**. *Nerves* - Tumors of neural origin, such as **optic nerve gliomas** or **meningiomas**, are less common than vascular tumors. - While significant, they do not represent the *most* common overall origin for orbital tumors. *Muscle* - Tumors originating from muscle, such as **rhabdomyosarcoma** in children (a malignant tumor), are relatively rare. - **Pseudotumor** (idiopathic orbital inflammation), though common, is an inflammatory condition, not a true neoplasm of muscle origin. *Lymph node* - Tumors of lymphoid origin, such as **lymphomas**, are malignant and can occur in the orbit. - However, they are not the most common primary orbital tumor compared to those of vascular origin.

Q: What is the most common cause of intermittent proptosis in adults?

Orbital varix. ***Orbital varix*** - An **orbital varix** is essentially a varicose vein within the orbit, which can cause intermittent proptosis. - Proptosis in an orbital varix is often exacerbated by activities that increase venous pressure, such as **Valsalva maneuvers**, crying, or bending over. *Thyroid ophthalmopathy* - This condition is characterized by **persistent proptosis**, lid retraction, and ophthalmoplegia, rather than intermittent symptoms. - While it can cause proptosis, it typically presents as **constant and progressive** rather than intermittent proptosis that varies with head position or straining. *Neuroblastoma* - This is a **malignant tumor** that primarily affects infants and young children, not typically adults. - Orbital metastasis from neuroblastoma would cause **progressive, constant proptosis** rather than intermittent proptosis. *Retinoblastoma* - **Retinoblastoma** is a malignant tumor of the retina that primarily affects young children, typically under the age of 5. - While it can cause proptosis in advanced stages, it presents as **constant and progressive proptosis** due to tumor growth, not intermittent proptosis.

Q: What is the first sign of iridocyclitis?

Aqueous flare. ***Aqueous flare*** - This is the earliest and most subtle sign, representing an increase in **protein content** in the aqueous humor due to breakdown of the **blood-aqueous barrier**. - It is detected by a **slit-lamp examination** as a hazy appearance in the anterior chamber, similar to a car headlight beam in fog. *KP* - **Keratic precipitates (KP)** are deposits of inflammatory cells on the corneal endothelium. - While characteristic of iridocyclitis, they typically appear **after** the initial breakdown of the blood-aqueous barrier that causes aqueous flare. *Congestion* - **Ciliary congestion** (perilimbal redness) is a common symptom of anterior uveitis, but it is a visible sign of inflammation. - The underlying inflammatory process causing the congestion first manifests as **subtle changes in the aqueous humor**, which is aqueous flare. *Trichiasis* - **Trichiasis** is the misdirection of eyelashes to rub against the cornea, causing irritation. - It is an **external ocular condition** and is not a sign of intraocular inflammation like iridocyclitis.

Q: In the context of homocystinuria, which direction does the lens typically subluxate?

Inferonasal. ***Inferonasal*** - In **homocystinuria**, the **ectopia lentis** (lens subluxation) often occurs due to weakening of the **zonular fibers**. - The classic direction for lens subluxation in homocystinuria is **inferior and nasal**. *Inferotemporal* - While lens subluxation can occur in various directions, **inferotemporal** is not the classic or most common presentation in homocystinuria. - This direction is less specific and does not strongly point to homocystinuria as the underlying cause. *Superonasal* - **Superonasal** dislocation of the lens is more characteristic of **Marfan syndrome**, which is important to differentiate from homocystinuria. - This direction helps distinguish different causes of lens ectopia. *Superotemporal* - **Superotemporal** lens subluxation is the hallmark of **Marfan syndrome**, a genetic connective tissue disorder. - This specific finding is crucial for differential diagnosis in patients presenting with lens ectopia.

Q: Which of the following is a selective serotonin and norepinephrine reuptake inhibitor?

Venlafaxine. ***Venlafaxine*** - **Venlafaxine** is a commonly used antidepressant that inhibits the reuptake of both **serotonin** and **norepinephrine**, making it an SNRI. - Its dual mechanism of action can be effective for a broad range of depressive and anxiety disorders. *Fluoxetine* - **Fluoxetine** is a **selective serotonin reuptake inhibitor (SSRI)**, primarily affecting serotonin levels in the brain. - It does not significantly inhibit norepinephrine reuptake and, thus, is not classified as an SNRI. *Sertraline* - **Sertraline** is another widely prescribed antidepressant that is also a **selective serotonin reuptake inhibitor (SSRI)**. - It works mainly by increasing serotonin availability in the synaptic cleft. *Aripiprazole* - **Aripiprazole** is an **atypical antipsychotic** medication, often used as an adjunct therapy for depression, but its primary mechanism is partial agonism at dopamine D2 and serotonin 5-HT1A receptors, and antagonism at serotonin 5-HT2A receptors. - It is not classified as a selective serotonin and norepinephrine reuptake inhibitor.

Q: What is the duration of the second heart sound (S2)?

0.08 sec. ***0.08 sec*** - The second heart sound (S2) is composed of two components: A2 (aortic valve closure) and P2 (pulmonic valve closure). The normal duration of S2, encompassing both components, is approximately **0.08 seconds**. - This short duration reflects the rapid closure of the aortic and pulmonic valves at the beginning of **diastole**. *0.15sec* - A duration of **0.15 seconds** for S2 is significantly longer than normal, which could indicate abnormal valve function or conditions causing delayed valve closure. - Such prolonged duration might be observed in conditions like **severe pulmonic stenosis** or **pulmonic hypertension**, which are not the typical duration of a healthy S2. *0.12 sec* - A duration of **0.12 seconds** is also longer than the typical normal range for S2. - While still shorter than 0.15 seconds, it could suggest subtle delays in valve closure or splitting that exceeds the usual physiological splitting. *0.1 sec* - A duration of **0.1 seconds** is slightly prolonged but generally falls within a range that might be considered borderline or indicative of minimal physiological variations. - However, in typical healthy individuals, the S2 duration is closer to 0.08 seconds, making 0.1 seconds less precise for the most common duration.

Question 1

What is the most common protozoan associated with keratitis?

Accepted Answer

Acanthamoeba

Answer

Plasmodium

Answer

Toxoplasma

Answer

Entamoeba histolytica

Question 2

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 3

Which muscle is the earliest to be involved in thyroid ophthalmopathy?

Accepted Answer

Inferior Rectus (IR)

Answer

Medial Rectus (MR)

Answer

Superior Rectus (SR)

Answer

Lateral Rectus (LR)

Question 4

What is the treatment of choice for amblyopia?

Accepted Answer

Occlusion therapy

Answer

Corrective spectacles

Answer

Surgical intervention

Answer

Convergent exercises for vision therapy

Question 5

Most common orbital tumor has its origin from?

Accepted Answer

Blood vessels

Answer

Nerves

Answer

Muscle

Answer

Lymph node

Question 6

What is the most common cause of intermittent proptosis in adults?

Accepted Answer

Orbital varix

Answer

Thyroid ophthalmopathy

Answer

Neuroblastoma

Answer

Retinoblastoma

Question 7

What is the first sign of iridocyclitis?

Accepted Answer

Aqueous flare

Answer

KP

Answer

Congestion

Answer

Trichiasis

Question 8

In the context of homocystinuria, which direction does the lens typically subluxate?

Accepted Answer

Inferonasal

Answer

Inferotemporal

Answer

Superonasal

Answer

Superotemporal

Question 9

Which of the following is a selective serotonin and norepinephrine reuptake inhibitor?

Accepted Answer

Venlafaxine

Answer

Fluoxetine

Answer

Sertraline

Answer

Aripiprazole

Question 10

What is the duration of the second heart sound (S2)?

Accepted Answer

0.08 sec

Answer

0.15 sec

Answer

0.1 sec

Answer

0.12 sec

NEET-PG 2012

Microbiology

Ophthalmology

Pharmacology

Physiology