Anatomy
1 questionsUnilateral lacrimal gland destruction may be caused by?
NEET-PG 2012 - Anatomy NEET-PG Practice Questions and MCQs
Question 681: Unilateral lacrimal gland destruction may be caused by?
- A. Fracture of roof of orbit (Correct Answer)
- B. Inferior orbital fissure fracture
- C. Fracture of lateral wall
- D. Fracture of sphenoid
Explanation: ***Fracture of roof of orbit*** - The **lacrimal gland** is situated in the **lacrimal fossa** on the anterior-lateral part of the **orbital roof**. A fracture in this specific area can directly damage the gland. - Trauma to the **orbital roof** can lead to laceration, avulsion, or compression of the lacrimal gland, resulting in its destruction and impairing tear production. *Inferior orbital fissure fracture* - The **inferior orbital fissure** transmits nerves and vessels to the orbit but is located inferior to the lacrimal gland, making direct injury unlikely. - Fractures here are more associated with **infraorbital nerve damage** or disruption of orbital contents into the maxillary sinus, not lacrimal gland destruction. *Fracture of lateral wall* - The **lateral wall of the orbit** forms the outer boundary and protects structures deeper within the orbit, but the lacrimal gland is situated superiorly and anteriorly. - While significant trauma to the lateral wall can impact orbital contents, it is less likely to directly cause unilateral lacrimal gland destruction compared to a direct roof fracture. *Fracture of sphenoid* - Fractures of the **sphenoid bone** are typically more posterior and central, affecting structures like the **optic canal** or **cavernous sinus**. - While it can indirectly affect orbital function, it is not a direct cause of isolated lacrimal gland destruction due to its anatomical location.
Microbiology
2 questionsInfluenza virus culture is done on ?
Colorado Tick fever is caused by:
NEET-PG 2012 - Microbiology NEET-PG Practice Questions and MCQs
Question 681: Influenza virus culture is done on ?
- A. Chorioallantoic membrane
- B. Allantoic cavity (Correct Answer)
- C. Yolk sac
- D. All of the options
Explanation: ***Allantoic cavity*** - The **allantoic cavity** of embryonated chicken eggs is the standard and most effective site for isolating and propagating **influenza viruses** for vaccine production and research. - This cavity provides an optimal environment for viral replication, particularly yielding high titers of **hemagglutinin**, a key influenza antigen. *Chorioallantoic membrane* - While embryonated eggs are used for virus culture, the **chorioallantoic membrane (CAM)** is primarily used for cultivating viruses that produce **pocks** (visible lesions), such as Vaccinia and Herpes Simplex Virus. - Influenza virus growth on the CAM is less efficient and typically doesn't produce distinct pocks, making it unsuitable for high-yield propagation compared to the allantoic cavity. *Yolk sac* - The **yolk sac** of embryonated eggs is ideal for growing viruses or bacteria that require a **lipid-rich environment** and replicate intracellularly, such as Chlamydia or Rickettsia. - It is not the preferred site for influenza virus isolation or proliferation due to suboptimal conditions for viral replication and lower viral yields. *All of the options* - While all these sites are components of an embryonated chicken egg, each serves as a host for different types of microorganisms or for specific purposes in virology. - For **influenza virus culture**, the **allantoic cavity** is the specifically utilized site for optimal growth and high viral yield.
Question 682: Colorado Tick fever is caused by:
- A. Coronaviridae
- B. Filoviridae
- C. Caliciviridae
- D. Reoviridae (Correct Answer)
Explanation: ***Reoviridae*** - Colorado Tick Fever (CTF) is caused by the **Colorado Tick Fever Virus (CTFV)**, which belongs to the genus **Coltivirus** within the family **Reoviridae**. - Reoviridae viruses are **non-enveloped**, double-stranded RNA viruses. *Filoviridae* - This family includes viruses like **Ebola virus** and **Marburg virus**, which cause severe hemorrhagic fevers. - They are **enveloped**, negative-sense single-stranded RNA viruses, distinct from the CTFV. *Coronaviridae* - This family includes viruses like **SARS-CoV-2 (COVID-19)** and SARS-CoV, which cause respiratory illnesses. - They are **enveloped**, positive-sense single-stranded RNA viruses, structurally different from CTFV. *Caliciviridae* - This family includes viruses like **Norovirus**, a common cause of acute gastroenteritis (viral stomach flu). - They are **non-enveloped**, positive-sense single-stranded RNA viruses and do not cause tick-borne illnesses.
Ophthalmology
7 questionsWhich of the following conditions is least likely to be associated with neovascular glaucoma?
Laser iridotomy is done in?
What type of deposit is commonly associated with age-related macular degeneration?
What does extraretinal fibrovascular proliferation at the ridge indicate?
In which condition is the swinging light test positive?
Most common malignant tumour of eyelid is ?
Bilateral ptosis is seen in all except which of the following?
NEET-PG 2012 - Ophthalmology NEET-PG Practice Questions and MCQs
Question 681: Which of the following conditions is least likely to be associated with neovascular glaucoma?
- A. Diabetes
- B. Open angle glaucoma (Correct Answer)
- C. CRVO
- D. Eale's disease
Explanation: ***Open angle glaucoma*** ✓ - **Open-angle glaucoma** is a primary **neurodegenerative disease** of the optic nerve, characterized by progressive loss of **retinal ganglion cells** and their axons, leading to characteristic **optic neuropathy** and visual field defects. - It does **NOT** directly cause **neovascularization** or increased VEGF production, which are the underlying mechanisms for **neovascular glaucoma**. - This is the **least likely** association among the given options. *Diabetes* - **Diabetic retinopathy** is a **major cause** of **neovascularization** due to retinal ischemia and increased production of **vascular endothelial growth factor (VEGF)**, which can lead to **neovascular glaucoma**. - **Neovascularization** on the iris (rubeosis iridis) and angle can block aqueous outflow, causing a severe, rapidly progressing form of secondary glaucoma. *CRVO (Central Retinal Vein Occlusion)* - **CRVO** leads to significant retinal ischemia and subsequent release of **VEGF**, which prompts the growth of new, fragile blood vessels. - These new vessels (neovascularization) can grow in the iris and angle, obstructing aqueous humor outflow and causing **neovascular glaucoma**. - **Ischemic CRVO** is one of the **most common causes** of neovascular glaucoma. *Eale's disease* - **Eale's disease** is an **idiopathic occlusive vasculitis** primarily affecting the **peripheral retinal veins**, leading to **retinal ischemia**. - This ischemia stimulates **neovascularization** and the production of **VEGF**, increasing the risk of **neovascular glaucoma** due to the formation of new blood vessels in the anterior chamber.
Question 682: Laser iridotomy is done in?
- A. Pigmentary glaucoma
- B. None of the options
- C. Angle closure glaucoma (Correct Answer)
- D. Open angle glaucoma
Explanation: ***Angle closure glaucoma*** - **Laser iridotomy** creates a small hole in the iris, allowing aqueous humor to flow directly from the posterior to the anterior chamber, thus relieving pupillary block and opening the angle. - This procedure is the definitive treatment to prevent further **angle closure attacks** and is also used prophylactically in eyes at risk. *Open angle glaucoma* - This condition involves an **open angle** but impaired outflow of aqueous humor through the **trabecular meshwork**. - Laser iridotomy is not indicated as it does not address the primary outflow obstruction in the trabecular meshwork. *Pigmentary glaucoma* - This is a type of **open-angle glaucoma** caused by pigment dispersion that clogs the trabecular meshwork, leading to increased intraocular pressure. - While pigment can be released from the iris, the primary issue is the **trabecular meshwork obstruction**, which is not directly resolved by iridotomy. *None of the options* - This option is incorrect because **angle closure glaucoma** is a clear indication for laser iridotomy.
Question 683: What type of deposit is commonly associated with age-related macular degeneration?
- A. Iron
- B. Drusen (Correct Answer)
- C. Lipochrome
- D. Hemosiderine
Explanation: ***Drusen*** - **Drusen** are yellow deposits of extracellular material that accumulate beneath the **retinal pigment epithelium (RPE)**. - Their presence is a hallmark sign of **age-related macular degeneration (AMD)** and can lead to vision loss by disrupting retinal function. *Iron* - While iron can accumulate in ocular tissues in conditions like **siderosis bulbi** (due to retained intraocular foreign bodies), it is not a characteristic deposit of macular degeneration. - Ocular iron deposition typically causes different pathologies, such as retinal dysfunction or glaucoma, rather than AMD. *Lipochrome* - **Lipochrome** refers to a class of pigments, including **lipofuscin**, which can accumulate in cells as a byproduct of cellular metabolism and aging. - Although lipofuscin buildup occurs in the RPE with age, **drusen** are the specific, organized extracellular deposits pathognomonic for macular degeneration. *Hemosiderine* - **Hemosiderin** is an iron-storage complex formed from the breakdown of hemoglobin, found in situations of hemorrhage or chronic bleeding. - It is not a typical deposit found in macular degeneration; its presence in the retina usually indicates a history of retinal hemorrhage.
Question 684: What does extraretinal fibrovascular proliferation at the ridge indicate?
- A. Normal retina
- B. Stage II Retinopathy of Prematurity
- C. Stage III Retinopathy of Prematurity (Correct Answer)
- D. Stage I Retinopathy of Prematurity
Explanation: ***Stage III Retinopathy of Prematurity*** - Extraretinal fibrovascular proliferation at the ridge is the defining characteristic of **Stage III Retinopathy of Prematurity (ROP)**. - This stage signifies significant **neovascularization** extending into the vitreous, increasing the risk of **retinal detachment**. *Normal retina* - A normal retina does not exhibit **fibrovascular proliferation** or a distinct ridge, as its vascularization is fully developed and confined to the retinal plane. - Absence of any abnormal vascular growth or demarcation line indicates a healthy, mature retinal structure. *Stage II Retinopathy of Prematurity* - Stage II ROP is characterized by a **ridge** that is elevated and appears three-dimensional, but it **lacks extraretinal fibrovascular proliferation**. - This stage represents progression from Stage I, where the demarcation line becomes a prominent ridge, but without new vessel formation outside the retina. *Stage I Retinopathy of Prematurity* - Stage I ROP is characterized by a thin, flat **demarcation line** distinguishing vascularized from avascular retina, without any significant elevation or fibrovascular proliferation. - This initial stage indicates an arrested phase of retinal vascular development, but without the more severe signs of neovascularization.
Question 685: 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 686: Most common malignant tumour of eyelid is ?
- A. Basal cell carcinoma (Correct Answer)
- B. Malignant melanoma
- C. Squamous cell carcinoma
- D. Sebaceous gland carcinoma
Explanation: ***Basal cell carcinoma*** - **Basal cell carcinoma (BCC)** accounts for approximately 85-95% of all eyelid malignancies, making it the most common type. - It often presents as a **pearly nodule** with telangiectatic vessels, frequently affecting the lower eyelid. *Squamous cell carcinoma* - **Squamous cell carcinoma (SCC)** is the second most common eyelid malignancy, but it is significantly less frequent (5-10%) than BCC. - SCC has a **higher metastatic potential** compared to BCC. *Malignant melanoma* - **Malignant melanoma** is a rare but highly aggressive eyelid tumor, accounting for less than 1% of all eyelid malignancies. - It is characterized by its **pigmented appearance** and rapid growth pattern. *Sebaceous gland carcinoma* - **Sebaceous gland carcinoma** is a relatively uncommon, but aggressive, tumor of the eyelid, comprising about 1-5% of cases. - It often mimics benign lesions like a **chalazion** or chronic blepharitis, leading to delayed diagnosis.
Question 687: Bilateral ptosis is seen in all except which of the following?
- A. Trauma
- B. Hyperthyroidism (Graves' disease) (Correct Answer)
- C. Congenital
- D. Myotonic dystrophy
Explanation: ***Hyperthyroidism (Graves' disease)*** - **Hyperthyroidism** causes eyelid retraction, leading to a **stare** or **lid lag**, rather than **ptosis**. - **Graves' ophthalmopathy** can cause proptosis (bulging eyes) and conjunctival injection, but does not typically manifest as ptosis. *Congenital* - **Congenital ptosis** is often present at birth due to improper development of the **levator palpebrae superioris muscle**. - It can be **bilateral** and is usually isolated, without other systemic symptoms. *Trauma* - **Traumatic ptosis** can occur if the **levator muscle**, **aponeurosis**, or **third cranial nerve** is damaged. - This can be **bilateral** depending on the nature and extent of the head trauma. *Myotonic dystrophy* - **Myotonic dystrophy** is a **hereditary muscle disorder** characterized by progressive muscle weakness. - **Bilateral ptosis** is a very common early sign of **myotonic dystrophy**, often accompanied by **facial weakness** and **myotonia**.