Diseases of the Cornea Practice Questions

Q: Munson's sign is a feature of ?

Keratoconus. ***Keratoconus*** - **Munson's sign** is observed in advanced keratoconus, where the **conical protrusion of the cornea** indents the lower eyelid on downgaze. - This sign indicates significant **corneal thinning and steepening**. *Corneal ulcer* - A **corneal ulcer** is an open sore on the cornea, often caused by infection or trauma. - It presents with pain, redness, tearing, and photophobia, and does not cause **Munson's sign**. *Pterygium* - **Pterygium** is a triangular growth of conjunctival tissue that extends onto the cornea. - It is typically associated with UV exposure and does not cause corneal shape changes leading to **Munson's sign**. *Posterior staphyloma* - A **posterior staphyloma** is an outpouching of the posterior sclera, often seen in high myopia. - This condition affects the posterior segment of the eye and does not manifest with **Munson's sign**, which is an anterior corneal finding.

Q: All are true about Bullous keratopathy except which of the following?

Seen in Macular dystrophy. ***Seen in Macular dystrophy*** - **Bullous keratopathy** is a condition caused by endothelial dysfunction leading to corneal edema and bullae formation. - While macular corneal dystrophy is a condition characterized by corneal clouding due to mucopolysaccharide deposits in the stroma, it typically does not directly cause bullous keratopathy. *Treatment is lamellar keratoplasty* - **Lamellar keratoplasty** (e.g., DSAEK, DMEK) is a common surgical treatment for bullous keratopathy, where diseased posterior corneal layers are replaced. - The goal is to replace the dysfunctional endothelium and restore corneal clarity and function. *Lenses can be prescribed for such patients* - **Contact lenses**, particularly bandage contact lenses, can be prescribed to patients with bullous keratopathy to protect the cornea and alleviate pain. - They act as a physical barrier against ruptured bullae, promoting epithelial healing and comfort. *Seen in Fuchs' dystrophy* - **Fuchs' endothelial dystrophy** is a common cause of bullous keratopathy, where there's a progressive loss of corneal endothelial cells. - This endothelial dysfunction leads to an accumulation of fluid within the cornea, causing edema and the formation of epithelial bullae.

Q: Quantification of corneal sensation is done by?

Aesthesiometer. ***Aesthesiometer*** - An **aesthesiometer** is a specialized device used to measure the **corneal sensation** or sensitivity, typically by applying a controlled stimulus to the corneal surface. - It helps in diagnosing conditions affecting **corneal nerves**, such as **diabetic neuropathy** or post-surgical nerve damage. *Pachymeter* - A **pachymeter** is an ultrasonic device used to measure the **central corneal thickness (CCT)**. - This measurement is crucial for **intraocular pressure (IOP)** interpretation and evaluating conditions like **corneal edema** or **Fuchs' endothelial dystrophy**. *Keratometer* - A **keratometer** is an ophthalmic instrument used to measure the **curvature of the anterior surface of the cornea**. - It is primarily used to assess **corneal astigmatism** and to fit **contact lenses**. *Tonometer* - A **tonometer** is an instrument used to measure **intraocular pressure (IOP)**, which is essential for diagnosing and managing **glaucoma**. - It does not quantify corneal sensation but rather the **fluid pressure within the eye**.

Q: What is the dye and filter used to diagnose corneal ulcers?

Fluorescein dye - visualized under cobalt blue filter. ***Fluorescein dye - visualized under cobalt blue filter*** - **Fluorescein dye** is applied to the eye, and it stains areas of **epithelial defects**, such as those found in corneal ulcers, appearing bright green. - The **cobalt blue filter** enhances the visibility and fluorescence of the stained areas, making corneal ulcers clearly discernible. *Lissamine green dye - visualized under green filter* - **Lissamine green** is used to identify **devitalized cells** and **mucous filaments** on the ocular surface, rather than primary corneal epithelial defects. - It is visualized under **white light or red-free filter**, not a green filter, and is less suitable for diagnosing corneal ulcers directly. *Lissamine blue dye - visualized under cobalt blue filter* - This option refers to a non-existent dye combination for routine corneal ulcer diagnosis. **Lissamine blue** is not a standard ophthalmic dye for this purpose. - While a cobalt blue filter is used with fluorescein, it is not paired with a "Lissamine blue dye." *Fluorescein dye - visualized under green filter* - **Fluorescein dye** is indeed the correct dye for diagnosing corneal ulcers by staining epithelial defects. - However, it is visualized under a **cobalt blue filter**, not a green filter, to maximize fluorescence and contrast.

Q: What is a characteristic finding in fungal corneal ulcers?

Satellite lesions. ***Satellite lesions*** - **Fungal corneal ulcers** often present with characteristic **satellite lesions**, which are smaller, adjacent infiltrates surrounding the main ulcer. - These lesions indicate the spread of fungal hyphae into the surrounding corneal stroma. - This is the **most characteristic feature** that helps distinguish fungal from bacterial keratitis. *Dendritic ulcer* - A **dendritic ulcer** is pathognomonic for **herpes simplex keratitis**, not fungal infections. - It presents as a branching, tree-like epithelial defect, which is distinct from the appearance of fungal ulcers. *Ring abscess* - A **ring abscess** is more commonly associated with **Acanthamoeba keratitis** or severe bacterial infections. - While it can occur in very advanced fungal infections, it is not a characteristic initial finding. *White hypopyon* - While fungal keratitis can present with a **white, fluffy hypopyon**, this is not specific enough to be the most characteristic finding. - Hypopyon indicates severe inflammation and can be seen in bacterial, fungal, and other severe corneal infections. - The presence of **satellite lesions** remains the key distinguishing feature for fungal etiology.

Q: Kayser-Fleischer rings (KF rings) are seen in:

Wilson's disease. ***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.

Q: Which organism can penetrate corneal endothelium?

Haemophilus influenzae. ***Haemophilus influenzae*** - *Haemophilus influenzae* is unique in its ability to penetrate the **intact corneal endothelium** through its specific virulence factors and enzymatic mechanisms. - Along with *Neisseria meningitidis*, it can breach the **Descemet's membrane and endothelial barrier** without requiring prior epithelial damage. - This property makes it particularly dangerous as it can cause **endophthalmitis** by directly accessing the anterior chamber. *Neisseria gonorrhoeae* - While highly virulent, *N. gonorrhoeae* penetrates the **corneal epithelium** (outer layer) through its proteases, not the endothelium (inner layer). - It causes severe **hyperacute conjunctivitis** and can lead to **corneal perforation**, but via epithelial destruction and stromal infiltration. *Staphylococcus aureus* - A common cause of **bacterial keratitis** following epithelial defects or trauma. - Causes stromal infiltration and abscess formation but **cannot penetrate intact endothelium**. *Aspergillus fumigatus* - This fungus causes **fungal keratitis** typically after trauma with vegetative matter. - Invades through **epithelial breaches** and stromal infiltration, not through intact endothelial penetration.

Q: Kayser-Fleischer ring is found in which layer of cornea?

Descemet's membrane. ***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.

Q: Unilateral frontal blisters with upper lid edema and conjunctivitis is seen in?

Herpes Zoster Ophthalmicus. ***Herpes Zoster Ophthalmicus*** - This condition is characterized by a **unilateral vesicular rash** (blisters) in the **trigeminal dermatome (V1)**, which includes the forehead and upper eyelid, along with significant **lid edema** and **conjunctivitis**. - **Hutchinson's sign** (lesions on the tip, side, or root of the nose) indicates a high risk of ocular involvement due to the nasociliary nerve innervation. *Acanthamoeba Keratitis* - This is an **amoebic infection** of the cornea typically associated with **contact lens wear** and often presents with severe pain and a **ring infiltrate** in the cornea. - It does not typically present with unilateral frontal blisters or significant lid edema. *Herpes Simplex* - Herpes simplex typically causes **recurrent corneal ulcers** (dendritic or geographic) and sometimes blepharitis, but not the widespread **unilateral frontal blisters** seen in the trigeminal distribution. - While it can cause conjunctivitis and lid edema, the pattern of skin lesions is the key differentiator. *Neuroparalytic Keratitis* - This condition results from **trigeminal nerve damage**, leading to corneal anesthesia and subsequent **trophic corneal ulceration**. - It presents primarily with **corneal findings** (epithelial defects, ulcers) due to impaired sensation and tear film stability, not initial vesicular skin lesions or prominent lid edema.

Question 1

Munson's sign is a feature of ?

Accepted Answer

Keratoconus

Answer

Corneal ulcer

Answer

Pterygium

Answer

Posterior staphyloma

Question 2

All are true about Bullous keratopathy except which of the following?

Accepted Answer

Seen in Macular dystrophy

Answer

Lenses can be prescribed for such patients

Answer

Seen in Fuchs' dystrophy

Answer

Treatment is lamellar keratoplasty

Question 3

Quantification of corneal sensation is done by?

Accepted Answer

Aesthesiometer

Answer

Pachymeter

Answer

Keratometer

Answer

Tonometer

Question 4

What is the dye and filter used to diagnose corneal ulcers?

Accepted Answer

Fluorescein dye - visualized under cobalt blue filter

Answer

Lissamine green dye - visualized under green filter

Answer

Lissamine blue dye - visualized under cobalt blue filter

Answer

Fluorescein dye - visualized under green filter

Question 5

What is a characteristic finding in fungal corneal ulcers?

Accepted Answer

Satellite lesions

Answer

Dendritic ulcer

Answer

Ring abscess

Answer

White hypopyon

Question 6

Kayser-Fleischer rings (KF rings) are seen in:

Accepted Answer

Wilson's disease

Answer

Pterygium

Answer

Hemochromatosis

Answer

Menke's kinked hair syndrome

Question 7

Which organism can penetrate corneal endothelium?

Accepted Answer

Haemophilus influenzae

Answer

Staphylococcus Aureus

Answer

Aspergillus fumigatus

Answer

Neisseria gonorrhoeae

Question 8

Kayser-Fleischer ring is found in which layer of cornea?

Accepted Answer

Descemet's membrane

Answer

Endothelium

Answer

Bowman's layer

Answer

Corneal stroma

Question 9

Unilateral frontal blisters with upper lid edema and conjunctivitis is seen in?

Accepted Answer

Herpes Zoster Ophthalmicus

Answer

Herpes Simplex

Answer

Neuroparalytic Keratitis

Answer

Acanthamoeba Keratitis

Question 10

A 30 year old man presents to the clinic with pain in the eye, watering, redness, and photophobia. Examination of his eyes shows circumcorneal congestion and keratic precipitates. Assertion: Keratic precipitates (KPs) are proteinaceous deposits that can occur in various patterns on the corneal endothelium. Reason: Mutton fat KPs are seen in granulomatous iridocyclitis and are composed of epithelioid cells and macrophages.

Accepted Answer

Both Assertion and Reason are true, and Reason is not the correct explanation for Assertion

Answer

Both Assertion and Reason are true, and Reason is the correct explanation for Assertion

Answer

Assertion is true, but Reason is false

Answer

Assertion is false but reason is true

Diseases of the Cornea — MCQs

Diseases of the Cornea — MCQs

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