Anatomy
1 questionsThe narrowest part of the nasal cavity is?
NEET-PG 2015 - Anatomy NEET-PG Practice Questions and MCQs
Question 761: The narrowest part of the nasal cavity is?
- A. Internal nasal valve (Correct Answer)
- B. Antrochoanal region
- C. 1st nasal turbinate
- D. External nasal valve
Explanation: ***Internal nasal valve*** - The **internal nasal valve** is considered the narrowest and most restrictive part of the **nasal airway**. - It is formed by the caudal border of the **upper lateral cartilage**, septum, and the head of the inferior turbinate. *Antrochoanal region* - The **antrochoanal region** is the posterior opening of the nasal cavity into the nasopharynx. - While it can be narrowed by polyps or mucosal swelling, it is not anatomically the **narrowest fixed point** of the nasal cavity. *1st nasal turbinate* - The **inferior turbinate** (often referred to as the 1st turbinate) can contribute to nasal resistance, especially when enlarged. - However, the turbinate itself is a structure that can vary in size and degree of congestion, but the **internal nasal valve** represents a consistently narrower anatomical choke point. *External nasal valve* - The **external nasal valve** is formed by the ala, columella, and nostril rim, and represents the entrance to the nasal cavity. - While it is a critical area for airflow, it is typically wider than the **internal nasal valve**.
Internal Medicine
1 questionsWhich of the following conditions does not typically cause subconjunctival hemorrhages?
NEET-PG 2015 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 761: Which of the following conditions does not typically cause subconjunctival hemorrhages?
- A. Whooping cough
- B. Scurvy
- C. Pellagra (Correct Answer)
- D. Purpura
Explanation: ***Pellagra*** - Pellagra is a **nutritional deficiency disease** caused by a lack of **niacin (vitamin B3)**, characterized by symptoms affecting the **skin, gastrointestinal tract, and nervous system** (dermatitis, diarrhea, dementia, and death if untreated) [1]. - It does **not typically cause subconjunctival hemorrhages** as it primarily affects other organ systems and isn't associated with vascular fragility in the conjunctiva like the other conditions listed [2]. *Whooping cough* - **Violent coughing paroxysms** in whooping cough (pertussis) can significantly increase **venous pressure in the head and neck**. - This elevated pressure can rupture small conjunctival blood vessels, leading to **subconjunctival hemorrhages**. *Scurvy* - Scurvy is caused by **vitamin C deficiency**, which is essential for collagen synthesis and maintaining **blood vessel integrity**. - Lack of vitamin C leads to **fragile capillaries**, making patients prone to bleeding, including **subconjunctival hemorrhages**. *Purpura* - Purpura refers to **purple-colored spots on the skin caused by bleeding underneath the skin**. It is a general term for various conditions characterized by **small vessel bleeding**. - These conditions often involve **vascular fragility or platelet abnormalities**, making individuals susceptible to bleeding in different sites, including the conjunctiva, resulting in **subconjunctival hemorrhages**.
Ophthalmology
8 questionsWhat does a lensometer measure?
Which of the following is not a standard treatment for myopia?
Sudden loss of vision without pain - Which of the following is NOT a cause?
All are true regarding cornea except:
Which of the following is NOT a cause of crystal keratopathy?
Kayser-Fleischer ring is found in which layer of cornea?
Kayser-Fleischer rings (KF rings) are seen in:
Posterior staphyloma is seen in which condition?
NEET-PG 2015 - Ophthalmology NEET-PG Practice Questions and MCQs
Question 761: What does a lensometer measure?
- A. Corneal topography
- B. Biochemical constitution of lens
- C. Power of IOL
- D. The refractive power of corrective lenses (Correct Answer)
Explanation: ***The refractive power of corrective lenses*** - A **lensometer**, also known as a focimeter or vertometer, is an ophthalmological instrument used to measure the **refractive power** of spectacle lenses, contact lenses, and intraocular lenses. - It determines parameters such as **sphere**, **cylinder**, and **axis**, providing essential information for dispensing and fabricating corrective eyewear. *Corneal topography* - **Corneal topography** maps the curvature and shape of the cornea and is performed by a **topographer**. - This instrument is primarily used to diagnose and monitor conditions like **keratoconus** and to plan refractive surgeries. *Biochemical constitution of lens* - The **biochemical constitution** of the lens refers to its molecular makeup, including proteins and metabolites. - This is typically assessed through laboratory techniques like **spectroscopy** or **chromatography**, not a lensometer. *Power of IOL* - While a lensometer can measure the power of an **intraocular lens (IOL)** once it is manufactured, the initial power calculation for an IOL before implantation is determined using **biometry** (e.g., A-scan ultrasound or optical biometry). - **Biometry** measures the axial length of the eye and corneal curvature to calculate the appropriate IOL power.
Question 762: Which of the following is not a standard treatment for myopia?
- A. Phakic intraocular lens
- B. Radial Keratotomy
- C. Holmium laser thermoplasty (Correct Answer)
- D. LASIK
Explanation: ***Holmium laser thermoplasty*** - This procedure was explored for the treatment of **hyperopia**, not myopia, as it aims to steepen the cornea to increase its refractive power. - It involves using a holmium laser to apply heat to the peripheral cornea, causing **collagen shrinkage** and steepening, which is the opposite of what is needed for myopia correction. *LASIK* - **LASIK (Laser-Assisted in Situ Keratomileusis)** is a common and effective surgical procedure for correcting myopia by reshaping the cornea to reduce its refractive power. - It involves creating a **corneal flap** and using an excimer laser to remove tissue from the underlying stromal bed. *Phakic intraocular lens* - **Phakic intraocular lenses (IOLs)** are implanted into the eye without removing the natural lens and are a standard treatment for moderate to high myopia, especially in patients not suitable for LASIK. - They work by adding refractive power to the eye, allowing light to focus correctly on the retina. *Radial Keratotomy* - **Radial Keratotomy (RK)** was an early surgical procedure for myopia, involving making radial incisions in the cornea to flatten it and reduce its refractive power. - Although largely replaced by LASIK due to its unpredictable outcomes and potential for glare and night vision problems, it was historically a standard treatment for myopia.
Question 763: Sudden loss of vision without pain - Which of the following is NOT a cause?
- A. CRAO
- B. CSR
- C. Acute congestive glaucoma (Correct Answer)
- D. Vitreous Hemorrhage
Explanation: ***Acute congestive glaucoma*** - This condition is characterized by **sudden, severe eye pain** along with blurred vision, redness, and a fixed, mid-dilated pupil. - The pain arises from abrupt elevation of **intraocular pressure**, which differentiates it from painless vision loss. *CRAO* - **Central Retinal Artery Occlusion** (CRAO) typically presents as **sudden, profound, painless monocular vision loss**. - Funduscopic examination often reveals a **cherry-red spot** in the fovea with generalized retinal whitening. *CSR* - **Central Serous Retinopathy** (CSR) causes **sudden, painless blurred vision** or a scotoma, often described as a "watery" or "shimmering" effect. - It involves leakage of fluid under the retina, typically in the macula. *Vitreous Hemorrhage* - Presents as **sudden, painless loss of vision** or a shower of floaters, often described as cobwebs or clouds. - It results from bleeding into the **vitreous cavity**, which can obscure the retina.
Question 764: All are true regarding cornea except:
- A. The cornea is richly vascular. (Correct Answer)
- B. Endothelium help in maintaining dehydrated state
- C. Oxygen is mostly derived by epithelium directly from the air through tear film
- D. Corneal thickness is greater at periphery than center
Explanation: ***The cornea is richly vascular.*** - The cornea is an **avascular** tissue, meaning it lacks blood vessels, which is crucial for its transparency. - This avascularity helps prevent light scatter and maintains clear vision. - The cornea receives nutrition from the **aqueous humor**, **tear film**, and **limbal blood vessels** through diffusion. *Endothelium help in maintaining dehydrated state* - The **corneal endothelium** actively pumps fluid out of the corneal stroma via **Na-K-ATPase pumps**, preventing swelling and maintaining its relative state of dehydration. - This **deturgescence** is essential for the cornea's transparency and optimal refractive power. *Oxygen is mostly derived by epithelium directly from the air through tear film* - The corneal **epithelium** primarily obtains oxygen directly from the atmosphere via the **tear film** when the eyes are open. - During sleep, oxygen is primarily supplied by the **palpebral conjunctival vessels**. *Corneal thickness is greater at periphery than center* - The cornea is **thinner at the center** (around 520-540 µm) and gradually **thicker towards the periphery** (around 600-640 µm). - This structural difference contributes to its optical properties and mechanical stability.
Question 765: Which of the following is NOT a cause of crystal keratopathy?
- A. Schnyder's Dystrophy
- B. Bietti's Dystrophy
- C. Diabetes (Correct Answer)
- D. Cystinosis
Explanation: ***Diabetes*** - While diabetes can cause various ocular complications, such as **diabetic retinopathy**, **neovascular glaucoma**, and **cataracts**, it is **not associated** with crystal keratopathy. - Corneal changes in diabetes might include epithelial defects or reduced corneal sensitivity, but **not the deposition of crystalline substances in the cornea**. - **This is the correct answer** as diabetes does NOT cause crystal keratopathy. *Cystinosis* - **Cystinosis** is a metabolic disorder characterized by the accumulation of **cystine crystals** throughout the body, including the **cornea**. - These crystals can lead to significant **photophobia**, **corneal erosions**, and visual impairment, making it a **classic cause of crystal keratopathy**. - Corneal involvement typically appears in childhood with diffuse crystalline deposits. *Schnyder's Dystrophy* - **Schnyder's corneal dystrophy** is an inherited corneal dystrophy characterized by the deposition of **cholesterol and lipid crystals** in the central and peripheral cornea. - This leads to **dense corneal opacification** and can significantly impair vision over time, representing a **classic cause of crystal keratopathy**. - The cornea shows characteristic subepithelial and stromal crystal deposits. *Bietti's Crystalline Dystrophy* - **Bietti's crystalline dystrophy** is a rare, inherited chorioretinal dystrophy characterized by **crystalline deposits primarily in the retina and choroid**. - While the name suggests crystalline involvement, these crystals are predominantly **intraretinal and do NOT typically cause corneal crystal deposits**. - Therefore, Bietti's is **NOT a typical cause of crystal keratopathy** (corneal disease), though minimal peripheral corneal crystals have been rarely reported in advanced cases. - The confusion arises from the word "crystalline" in its name, but the pathology is retinal, not corneal.
Question 766: Kayser-Fleischer ring is found in which layer of cornea?
- A. Endothelium
- B. Descemet's membrane (Correct Answer)
- C. Bowman's layer
- D. Corneal stroma
Explanation: ***Descemet's membrane*** - Kayser-Fleischer rings are caused by **copper deposition** at the periphery of the cornea, specifically within **Descemet's membrane**. - This membrane is located between the **corneal stroma** and the **endothelium**. *Bowman's layer* - Bowman's layer is a thin, acellular layer of the cornea that lies beneath the **corneal epithelium**. - While it plays a role in corneal integrity, it is not the site of **copper deposition** in Wilson's disease. *Corneal stroma* - The corneal stroma is the thickest layer of the cornea, composed primarily of **collagen fibrils**. - Although it contains most of the corneal mass, **copper deposition** in Kayser-Fleischer rings does not specifically occur within the main stromal layer. *Endothelium* - The corneal endothelium is the innermost layer of the cornea, responsible for maintaining **corneal deturgescence**. - While it is adjacent to Descemet's membrane, the copper rings are deposited in the membrane itself, not directly in the endothelial cell layer.
Question 767: Kayser-Fleischer rings (KF rings) are seen in:
- A. Pterygium
- B. Hemochromatosis
- C. Wilson's disease (Correct Answer)
- D. Menke's kinked hair syndrome
Explanation: ***Wilson's disease*** - **Kayser-Fleischer (KF) rings** are pathognomonic for **Wilson's disease**, resulting from **copper deposition** in the Descemet's membrane of the cornea. - This genetic disorder leads to excessive **copper accumulation** in the liver, brain, and other tissues due to impaired copper excretion. *Pterygium* - A **pterygium** is a benign growth of the **conjunctiva** that extends onto the cornea, typically appearing as a fleshy, triangular lesion. - It is not associated with systemic copper metabolism disorders or the presence of KF rings. *Hemochromatosis* - **Hemochromatosis** is a disorder of **iron overload**, leading to iron deposition in various organs, including the liver, heart, and pancreas. - It does not involve copper metabolism or the formation of corneal rings. *Menke's kinked hair syndrome* - **Menke's syndrome** is a genetic disorder characterized by **copper deficiency**, leading to impaired copper transport and utilization. - It presents with severe neurological deterioration, connective tissue abnormalities, and characteristic **kinky hair**, but not KF rings.
Question 768: Posterior staphyloma is seen in which condition?
- A. Myopia (Correct Answer)
- B. Hypermetropia
- C. Astigmatism
- D. Presbyopia
Explanation: ***Myopia*** - A **posterior staphyloma** is an outward bulging of the posterior sclera and choroid, which is a common complication of **high myopia**. - It occurs due to the excessive elongation of the eyeball in myopic eyes, leading to thinning and weakening of the posterior sclera. *Hypermetropia* - This condition involves the eye being too short or the cornea being too flat, causing light to focus behind the retina, and is not associated with posterior staphyloma. - Hypermetropia is typically associated with **smaller axial length** and doesn't lead to the structural changes that cause staphyloma. *Astigmatism* - Astigmatism results from an **irregular curvature of the cornea or lens**, causing light to focus at multiple points on the retina, leading to blurred vision. - It describes a refractive error related to the shape of the optical surfaces, not an outward bulging of the posterior eye wall. *Presbyopia* - This is an **age-related decline in the eye's ability to focus on near objects** due to hardening of the crystalline lens and weakening of the ciliary muscles. - Presbyopia is a normal aging process of the lens and has no association with the structural changes of the posterior sclera seen in staphyloma.