NEET-PG 2013 - Ophthalmology Practice Questions

Q: Which of the following statements about Fuchs' corneal dystrophy is incorrect?

Unilateral condition. ***Unilateral condition - INCORRECT STATEMENT*** - **Fuchs' corneal dystrophy** is typically a **bilateral condition**, although it can be asymmetric in its presentation. - The disease often affects both eyes, progressing from early morning blurriness to constant visual impairment. - This is the INCORRECT statement - Fuchs' is NOT unilateral. *Posterior dystrophy - Correct statement* - **Fuchs' corneal dystrophy** is classified as a posterior corneal dystrophy, meaning it primarily affects the **corneal endothelium** and Descemet's membrane. - This posterior involvement leads to the characteristic guttata and corneal edema. *Endothelial dystrophy - Correct statement* - It is fundamentally an **endothelial dystrophy**, resulting from primary dysfunction and loss of corneal endothelial cells. - The compromised endothelial pump function leads to **stromal edema** and reduced visual acuity. *Occurs in old age - Correct statement* - Fuchs' corneal dystrophy typically presents in **middle to old age**, with symptoms often becoming noticeable in individuals over 50. - While congenital forms of corneal dystrophy exist, Fuchs' is not usually one of them.

Q: The immune ring is a feature associated with which condition?

Fungal corneal ulcer. ***Fungal corneal ulcer*** - The **immune ring** (also known as a **Wessely ring**) is a characteristic sign seen in **fungal corneal ulcers**, particularly those caused by filamentous fungi. - It represents a **circumferential infiltrate** of immune cells and antigen-antibody complexes. *Interstitial keratitis* - Characterized by **stromal inflammation** without primary involvement of the epithelium or endothelium, often leading to ghost vessels after treatment. - It is typically associated with conditions like **syphilis** or other systemic infections, not an immune ring. *Bacterial corneal ulcer* - Often presents with a **rapidly progressing** corneal infiltrate, significant pain, and sometimes **hypopyon**. - While an immune response occurs, it does not typically form a distinct, well-defined **immune ring** like in fungal infections. *Herpes simplex keratitis* - Classically manifests as a **dendritic ulcer** or geographic ulcer, which can progress to stromal keratitis. - The immune ring is **not a feature** of herpes simplex keratitis; distinctive patterns like dendrites or disciform keratitis are seen.

Q: Krukenberg spindles -

Involve posterior surface of cornea. **Involve posterior surface of cornea** - **Krukenberg spindles** are vertical, spindle-shaped deposits of **pigment (melanin)** on the posterior surface of the cornea. - They are a characteristic finding in **pigment dispersion syndrome** and **pigmentary glaucoma**, where iris pigment is released and circulated in the aqueous humor, eventually depositing on the corneal endothelium. *Involve anterior surface of cornea* - Deposits on the anterior corneal surface are less common and typically indicate external factors or specific corneal dystrophies, not Krukenberg spindles. - **Krukenberg spindles** are specifically formed by pigment circulating within the anterior chamber, which deposits on the posterior corneal surface due to aqueous humor flow. *Involve anterior lens surface* - Pigment deposits can occur on the anterior lens capsule, but these are typically diffuse or in a "bull's eye" pattern and are not referred to as **Krukenberg spindles**. - **Krukenberg spindles** are defined by their specific "spindle" shape and location on the cornea. *Involve posterior surface of lens* - Deposits on the posterior lens surface are usually associated with specific conditions like **uveitis** (posterior synechiae) or related to retinal issues, not pigment dispersion syndrome or **Krukenberg spindles**. - The formation of **Krukenberg spindles** is directly linked to the flow of aqueous humor and gravity affecting pigment particles in the anterior chamber.

Q: What is the most common infection in contact lens users?

Pseudomonas. ***Pseudomonas*** - **Pseudomonas aeruginosa** is the leading cause of **bacterial keratitis** in contact lens wearers, accounting for 60-70% of culture-positive cases - This bacterium can **adhere to lenses**, form **biofilms**, and thrive in moist lens storage cases - Can cause rapid and severe corneal damage with **corneal ulceration**, potentially leading to **vision loss** *Staphylococcus* - **Staphylococcus aureus** and **Staphylococcus epidermidis** are common commensals of the skin and can cause eye infections, including keratitis and blepharitis - However, in the context of contact lens-related keratitis, **Pseudomonas aeruginosa** remains the primary pathogen for severe corneal infections *Streptococcus* - While various **Streptococcus species** (especially S. pneumoniae) can cause bacterial keratitis, they are less commonly associated with contact lens-related keratitis compared to Pseudomonas - **Streptococcal keratitis** typically occurs in non-contact lens wearers or after trauma *Neisseria* - **Neisseria gonorrhoeae** can cause hyperacute bacterial conjunctivitis with severe purulent discharge, but is not the most common cause of contact lens-related keratitis - **Neisseria meningitidis** can rarely cause conjunctivitis, but these infections usually indicate specific exposure or systemic disease

Q: What condition is associated with copper deposition in the cornea?

Wilson's disease. ***Wilson's disease*** - Wilson's disease is a genetic disorder of **copper metabolism** leading to excess copper accumulation in various tissues, including the cornea [1]. - This copper deposition in the posterior Descemet's membrane of the cornea forms a distinctive golden-brown or greenish-brown ring known as the **Kayser-Fleischer ring**. *Keratoconus* - This condition is characterized by progressive thinning and steepening of the cornea, causing it to bulge into a **cone-like shape**. - It primarily affects vision due to irregular astigmatism and does not involve copper deposition. *Keratoglobus* - Keratoglobus is a rare corneal ectatic disorder where the entire cornea is thinned and bulges forward, giving it a **globe-like appearance**. - It is congenital and typically runs in families, and it is not associated with copper deposition. *Siderosis* - Siderosis refers to the deposition of **iron** in various tissues, often due to chronic hemorrhage or metallic foreign bodies. - In the eye, it can occur after intraocular iron foreign bodies, leading to retinal degeneration and other ocular complications, but it does not involve copper.

Q: Which agent is known to cause corneal ulcers that may resemble fungal infections?

Nocardia asteroides. ***Nocardia asteroides*** - This organism can cause **Nocardia keratitis**, which often presents with a **feathery or crystalline appearance** in the cornea, mimicking a fungal infection. - It tends to occur in patients with **contact lens use** or ocular trauma and requires specific antimicrobial treatment different from fungal therapy. *Mycobacterium* - **Atypical mycobacteria** can cause chronic, indolent corneal ulcers, particularly after trauma or surgery. - While they can be challenging to diagnose, their appearance typically differs from the **feathery morphology** associated with fungal or Nocardia infections. *Klebsiella pneumoniae* - **Klebsiella pneumoniae** is a common cause of **bacterial keratitis**, especially in contact lens wearers. - Infections usually manifest as a rapidly progressing infiltrate with significant inflammation and often produce abundant **mucopurulent discharge**, not typically mistaken for fungal infections. *Chlamydia trachomatis* - **Chlamydia trachomatis** is the causative agent of **trachoma**, leading to recurrent conjunctivitis and eventually corneal scarring and blindness in endemic areas. - It does not cause acute corneal ulcers that resemble fungal infections; rather, it results in a chronic inflammatory process with **follicular conjunctivitis** and **pannus formation**.

Q: Schwalbe's ring is seen in which layer of the cornea?

Descemet's membrane. ***Descemet's membrane*** - Schwalbe's ring is a circular opacity representing the termination of **Descemet's membrane** at the periphery of the cornea, just anterior to the **trabecular meshwork**. - Its presence is a normal anatomical variant, but prominence can be associated with certain conditions like **posterior embryotoxon**. *Bowman's membrane* - This layer is found immediately beneath the **corneal epithelium** and does not extend to form Schwalbe's ring. - It is an acellular layer composed of collagen fibrils randomly arranged, offering resistance to infection and injury. *Stroma* - The stroma is the thickest layer of the cornea, composed primarily of **collagen lamellae** arranged in a highly organized manner. - It lies posterior to Bowman's membrane and anterior to Descemet's membrane, but its termination does not form Schwalbe's ring. *Substantia propria* - This is another name for the **corneal stroma**, which, as elaborated above, does not form Schwalbe's ring. - It comprises about 90% of the corneal thickness and provides the cornea's structural integrity and transparency.

Q: Ameboid ulcers are primarily associated with which type of corneal ulcer?

Acanthamoeba corneal ulcer. ***Acanthamoeba corneal ulcer*** - **Acanthamoeba** infections are classically associated with **ameboid ulcers** due to the movement and destructive nature of this protozoan. - This type of ulcer often presents with severe pain, disproportionate to clinical findings, and can have a **ring infiltrates** appearance. *Fungal corneal ulcer* - Fungal ulcers typically present with a **feathery border** and satellite lesions, not ameboid shapes. - They are often associated with a history of **ocular trauma** involving plant material. *Herpetic corneal ulcer* - Herpetic ulcers are characterized by a **dendritic pattern** (tree-branch-like), which is distinct from an ameboid shape. - They are caused by the **herpes simplex virus** and can lead to recurrent episodes. *Bacterial corneal ulcer* - Bacterial ulcers typically present as a **round or oval infiltrate** with stromal edema and an overlying epithelial defect. - They can progress rapidly and are not described as having an **ameboid configuration**.

Q: In specular microscopy endothelial density is measured by?

Fixed frame analysis. ***Fixed frame analysis*** - This is the **standard method** used in specular microscopy to measure corneal endothelial cell density. - It involves analyzing a specific, fixed area of the **endothelial mosaic** and counting the number of cells within that defined frame. - The cell count from this fixed area is then **extrapolated** to calculate the overall endothelial cell density (cells/mm²). - This technique provides **quantitative assessment** of endothelial health, which is crucial for evaluating corneal function and pre-operative assessment for intraocular surgeries. *Optical doubling* - This is not a standard method for measuring endothelial density in specular microscopy. - Optical doubling relates to **refractive phenomena** or optical measurement techniques used in other contexts, not for endothelial cell counting. *Optical focusing* - While **essential for image acquisition**, optical focusing is merely a preliminary step to obtain a clear, sharp image of the endothelium. - It does not measure or count cells; it only ensures proper visualization before analysis. - The actual measurement requires subsequent **cell counting methods** like fixed frame analysis. *None of the options* - Incorrect because **fixed frame analysis** is indeed the recognized and widely used method for measuring endothelial density in specular microscopy.

Q: Corneal sensations are decreased in all of the following conditions except:

Recurrent corneal erosion syndrome. ***Recurrent corneal erosion syndrome*** - This condition involves **defective adhesion** of the corneal epithelium to the underlying Bowman's layer and basement membrane, leading to sudden, severe pain upon waking. - While it causes **pain** and **epithelial defects**, it does not primarily involve nerve damage or decreased corneal sensation; rather, episodes are often very painful due to exposed nerve endings. *Herpetic keratitis* - Caused by the **herpes simplex virus (HSV)**, which can infect the trigeminal nerve and lead to **trophic changes** in the cornea. - This viral infection often results in **significant reduction** or loss of corneal sensation, making the eye more vulnerable to trauma and delayed healing. *Neuroparalytic keratitis* - This condition is also known as **neurotrophic keratitis** and results from damage to the **trigeminal nerve**, which supplies sensation to the cornea. - Loss of corneal sensation leads to impaired reflex tearing and blinking, making the cornea susceptible to epithelial breakdown and ulceration due to lack of protective mechanisms. *Leprosy* - In ocular leprosy, the **Mycobacterium leprae** directly invades the ciliary nerves, significantly impairing corneal sensation. - This reduced sensation in leprosy patients increases the risk of **corneal ulcers** and opacification due to undetected foreign bodies and trauma.

Question 1

Which of the following statements about Fuchs' corneal dystrophy is incorrect?

Accepted Answer

Unilateral condition

Answer

Endothelial dystrophy

Answer

Occurs in old age

Answer

Posterior dystrophy

Question 2

The immune ring is a feature associated with which condition?

Accepted Answer

Fungal corneal ulcer

Answer

Interstitial keratitis

Answer

Bacterial corneal ulcer

Answer

Herpes simplex keratitis

Question 3

Krukenberg spindles -

Accepted Answer

Involve posterior surface of cornea

Answer

Involve anterior surface of cornea

Answer

Involve anterior lens surface

Answer

Involve posterior surface of lens

Question 4

What is the most common infection in contact lens users?

Accepted Answer

Pseudomonas

Answer

Streptococcus

Answer

Staphylococcus

Answer

Neisseria

Question 5

What condition is associated with copper deposition in the cornea?

Accepted Answer

Wilson's disease

Answer

Keratoglobus

Answer

Keratoconus

Answer

Siderosis

Question 6

Which agent is known to cause corneal ulcers that may resemble fungal infections?

Accepted Answer

Nocardia asteroides

Answer

Mycobacterium

Answer

Klebsiella pneumoniae

Answer

Chlamydia trachomatis

Question 7

Schwalbe's ring is seen in which layer of the cornea?

Accepted Answer

Descemet's membrane

Answer

Bowman's membrane

Answer

Stroma

Answer

Substantia propria

Question 8

Ameboid ulcers are primarily associated with which type of corneal ulcer?

Accepted Answer

Acanthamoeba corneal ulcer

Answer

Fungal corneal ulcer

Answer

Bacterial corneal ulcer

Answer

Herpetic corneal ulcer

Question 9

In specular microscopy endothelial density is measured by?

Accepted Answer

Fixed frame analysis

Answer

None of the options

Answer

Optical doubling

Answer

Optical focusing

Question 10

Corneal sensations are decreased in all of the following conditions except:

Accepted Answer

Recurrent corneal erosion syndrome

Answer

Neuroparalytic keratitis

Answer

Leprosy

Answer

Herpetic keratitis

NEET-PG 2013 — Ophthalmology