Diseases of the Cornea Practice Questions

Q: Schwalbe's line represents the peripheral limit of which corneal layer?

Descemet's layer. **Explanation:** **Schwalbe’s line** is a critical anatomical landmark in the anterior chamber angle. It represents the **peripheral termination of Descemet’s membrane** (the basement membrane of the corneal endothelium). As the cornea transitions into the sclera at the limbus, Descemet’s membrane thickens and ends, forming this visible ridge. * **Why Option C is Correct:** Descemet’s membrane is a resilient, elastic layer. Its peripheral limit marks the anterior boundary of the trabecular meshwork. During gonioscopy, Schwalbe’s line is the most anterior structure identified in the angle. * **Why Options A & B are Incorrect:** **Bowman’s layer** (Option A) ends abruptly at the limbus and does not extend into the angle structures. The **Stroma** (Option B) is continuous with the sclera (corneoscleral junction) rather than ending at a specific "line." * **Why Option D is Incorrect:** The **Endothelium** (Option D) is a monolayer of cells that continues over the trabecular meshwork as the mesenchymal lining; it does not form the anatomical ridge known as Schwalbe’s line. **High-Yield Clinical Pearls for NEET-PG:** * **Gonioscopy:** Schwalbe’s line is the first structure seen from the "top" (anteriorly) when performing gonioscopy. * **Sampaolesi Line:** In Pigmentary Glaucoma or Pseudoexfoliation syndrome, dark pigment often deposits on or anterior to Schwalbe’s line, creating a "Sampaolesi line." * **Posterior Embryotoxon:** An abnormally thickened and anteriorly displaced Schwalbe’s line is termed "Posterior Embryotoxon," which can be an isolated finding or associated with **Alagille syndrome** or **Axenfeld-Rieger syndrome**.

Q: Which of the following is true of a dendritic ulcer?

Caused by Herpes simplex virus. **Explanation:** **Dendritic ulcer** is the classic clinical presentation of **Herpes Simplex Keratitis (HSK)**, specifically caused by the Herpes Simplex Virus Type 1 (HSV-1). 1. **Why Option A is correct:** The virus infects the corneal epithelium, leading to the formation of linear, branching (dendritic) lesions. These ulcers are characterized by **terminal bulbs** and stain vividly with **Fluorescein** (the bed) and **Rose Bengal** (the swollen margins containing live virus). 2. **Why Option B is incorrect:** Topical corticosteroids are **strictly contraindicated** in the presence of an active epithelial dendritic ulcer. Steroids promote viral replication, leading to the enlargement of the ulcer into a "geographic" or "amoeboid" ulcer and increasing the risk of corneal perforation. 3. **Why Option C is incorrect:** While oral acyclovir is used for recurrent HSK or stromal involvement, the **primary treatment** for a simple dendritic epithelial ulcer is **topical antiviral therapy** (e.g., Ganciclovir 0.15% gel or Acyclovir 3% ointment). Oral acyclovir is generally reserved for prophylaxis or complicated cases, making "A" the most definitive "true" statement regarding the etiology. **High-Yield Clinical Pearls for NEET-PG:** * **Hallmark Sign:** Reduced or absent corneal sensations (tested with a wisp of cotton). * **Staining:** Fluorescein stains the ulcer base; Rose Bengal/Lissamine Green stains the devitalized cells at the margin. * **Morphology:** True dendrites have **terminal bulbs**, which distinguish them from "pseudodendrites" seen in Acanthamoeba or Herpes Zoster Ophthalmicus. * **Treatment:** Debridement + Topical Antivirals. **Never use steroids in epithelial disease.**

Q: What happens to the corneal endothelium after injury?

Regenerates rapidly. ### Explanation The corneal endothelium is a single layer of hexagonal cells that plays a critical role in maintaining corneal dehydration (deturgescence) via the Na+/K+ ATPase pump. **Why "Regenerates rapidly" is the correct answer:** In the context of clinical ophthalmology and standard textbook descriptions (like Khurana), the corneal endothelium is described as having **no regenerative capacity** in humans. However, when an injury occurs, the defect is "repaired" or "regenerated" in a functional sense not by cell division (mitosis), but by the **rapid migration and enlargement (pleomorphism and polymegethism)** of existing neighboring cells to cover the gap. This process happens very quickly to restore the endothelial pump function and prevent corneal edema. *Note: In many competitive exams, "Regenerates rapidly" refers to this rapid compensatory migration rather than true mitotic division.* **Analysis of Incorrect Options:** * **A & B:** While technically true that mitotic regeneration is near zero, these options are often considered incorrect in the context of the "rapid" functional recovery seen after minor trauma or surgery. * **D. Forms a scar:** Scarring is a feature of the corneal **stroma** (involving myofibroblasts). The endothelium does not form a traditional opaque scar; it either recovers its barrier function or fails, leading to bullous keratopathy. **High-Yield NEET-PG Pearls:** * **Cell Count:** Normal adult count is **2500–3000 cells/mm²**. * **Critical Limit:** If the count falls below **500 cells/mm²**, corneal decompensation and edema occur. * **Specular Microscopy:** The gold standard investigation to assess endothelial cell density and morphology. * **Schwalbe’s Line:** Represents the peripheral termination of the endothelial layer (Descemet’s membrane).

Q: K F Ring is seen in which condition?

Chalcosis. **Explanation:** The **Kayser-Fleischer (KF) ring** is a classic clinical sign characterized by a golden-brown or greenish-brown pigment deposition in the **Descemet’s membrane** of the peripheral cornea. It is caused by the deposition of **copper**. 1. **Why Chalcosis is correct:** Chalcosis refers to the presence of intraocular copper (usually from a retained copper-containing foreign body). Since the KF ring is specifically a manifestation of copper deposition, it is seen in conditions of systemic copper overload (like **Wilson’s Disease**) or localized copper toxicity (**Chalcosis Bulbi**). In Wilson's disease, it starts superiorly, then inferiorly, and finally becomes circumferential. 2. **Why other options are incorrect:** * **Sarcoidosis:** Typically presents with granulomatous uveitis (Mutton-fat keratic precipitates) and "string of pearls" vitreous opacities, not copper deposition. * **Tuberous Sclerosis:** Associated with retinal astrocytic hamartomas (mulberry lesions), not corneal rings. * **VKH (Vogt-Koyanagi-Harada) Syndrome:** A multisystem autoimmune disease presenting with bilateral granulomatous panuveitis, exudative retinal detachment, and integumentary signs (poliosis, vitiligo), but no corneal copper rings. **High-Yield Clinical Pearls for NEET-PG:** * **Location:** KF rings are always found in the **Descemet’s membrane**. * **Best Visualization:** Early KF rings are best detected using a **Gonioscope**. * **Sunflower Cataract:** Another high-yield copper-related finding seen in Wilson’s disease/Chalcosis (deposition in the anterior lens capsule). * **Fleischer Ring:** Do not confuse KF ring with Fleischer ring (iron deposition at the base of the cone in **Keratoconus**). * **Ferry’s Line:** Iron line at the edge of a filtering bleb. * **Stocker’s Line:** Iron line at the head of a Pterygium.

Q: Cogan's syndrome is associated with which of the following?

Keratitis. **Explanation:** **Cogan’s Syndrome** is a rare, non-syphilitic autoimmune vasculitis primarily affecting young adults. The classic clinical triad consists of **Interstitial Keratitis (IK)**, vestibulo-auditory dysfunction (Meniere-like symptoms), and systemic vasculitis (notably aortitis). 1. **Why Keratitis is correct:** The hallmark ocular manifestation is **nonsyphilitic interstitial keratitis**. Patients typically present with sudden onset of photophobia, lacrimation, and blurred vision. Examination reveals patchy subepithelial infiltrates in the peripheral cornea, which can progress to deep corneal neovascularization. 2. **Why other options are incorrect:** * **Conjunctivitis:** While mild redness may occur, it is not a defining or diagnostic feature of the syndrome. * **Iritis:** Though secondary anterior uveitis can occur as a complication of severe keratitis, it is not the primary diagnostic association. * **Myopia:** There is no pathological link between Cogan’s syndrome and refractive errors like myopia. **High-Yield Clinical Pearls for NEET-PG:** * **The Triad:** Interstitial Keratitis + Vertigo/Tinnitus/Hearing loss + Systemic Vasculitis. * **Systemic Association:** Up to 10% of patients develop **Aortitis**, which can lead to life-threatening aortic insufficiency or aneurysms. * **Differential Diagnosis:** Always rule out **Syphilis** (the most common cause of IK) using FTA-ABS or VDRL tests. * **Treatment:** Topical steroids for ocular symptoms; systemic steroids or immunosuppressants (e.g., Cyclophosphamide) for auditory and systemic involvement. Early treatment is critical to prevent permanent deafness.

Q: Schwalbe's line represents:

The termination of Descemet's membrane. **Explanation:** **Schwalbe’s line** is a critical anatomical landmark in the anterior chamber angle. It represents the **peripheral termination of Descemet’s membrane** (the basement membrane of the corneal endothelium). Structurally, it marks the transition point where the corneal endothelium ends and the trabecular meshwork begins. **Analysis of Options:** * **Option B (Correct):** As the Descemet’s membrane reaches the limbus, it thickens and ends abruptly, forming a faint white ridge known as Schwalbe’s line. * **Option A:** The junction of the choroid and retina is the **Ora Serrata**, which marks the transition from the non-photosensitive ciliary epithelium to the photosensitive retina. * **Option C:** The division between the bulbar and palpebral conjunctiva is the **Conjunctival Fornix**. * **Option D:** There is no specific anatomical line named "Schwalbe's" for the macula; the macula is defined by its high density of xanthophyll pigment and cones. **Clinical Pearls for NEET-PG:** 1. **Gonioscopy:** Schwalbe’s line is the **most anterior (uppermost) structure** visible during gonioscopy. Identifying it is the first step in grading the angle. 2. **Sampaolesi Line:** In Pigmentary Glaucoma or Pseudoexfoliation Syndrome, pigment may deposit on or anterior to Schwalbe’s line, forming a "Sampaolesi line." 3. **Posterior Embryotoxon:** If Schwalbe’s line is thickened and anteriorly displaced (visible on slit-lamp exam without a goniolens), it is called Posterior Embryotoxon, often associated with **Alagille syndrome** or **Axenfeld-Rieger syndrome**.

Q: Bowman's membrane is seen in which structure?

Cornea. **Explanation:** The **Cornea** is the correct answer because Bowman’s membrane is one of its five primary histological layers. To remember the layers of the cornea from anterior to posterior, use the mnemonic **"ABCDE"**: 1. **A**nterior Epithelium 2. **B**owman’s Membrane (Anterior limiting membrane) 3. **C**orneal Stroma (Substantia propria) 4. **D**escemet’s Membrane (Posterior limiting membrane) 5. **E**ndothelium **Bowman’s membrane** is an acellular, condensed layer of collagen fibers. Its most significant clinical characteristic is that **it does not regenerate**; if damaged by trauma or ulceration, it heals by permanent scarring (opacification), which can lead to visual impairment. **Why other options are incorrect:** * **Conjunctiva:** This is a mucous membrane consisting of non-keratinized stratified columnar epithelium and a lamina propria (adenoid and fibrous layers), but it lacks a Bowman’s layer. * **Lens:** The lens consists of a capsule, anterior epithelium, and lens fibers. It is an avascular, transparent structure but does not contain Bowman’s membrane. * **Iris:** Part of the uveal tract, the iris consists of the anterior limiting layer, stroma, and posterior pigmented epithelium. **High-Yield Clinical Pearls for NEET-PG:** * **Regeneration:** Descemet’s membrane *can* regenerate (secreted by the endothelium), whereas Bowman’s membrane *cannot*. * **Keratoconus:** Characterized by early breaks in Bowman’s membrane. * **Reis-Bücklers Dystrophy:** A superficial corneal dystrophy specifically affecting Bowman’s layer. * **Thickness:** Bowman's membrane is approximately 8–14 microns thick.

Q: Corneal dystrophy associated with acid mucopolysaccharidosis is:

Macular. **Explanation:** The correct answer is **Macular Corneal Dystrophy (MCD)**. **Why Macular Dystrophy is correct:** Macular corneal dystrophy is an autosomal recessive condition (unlike most other stromal dystrophies which are autosomal dominant). It is characterized by the systemic and localized accumulation of **Acid Mucopolysaccharides** (specifically Keratan Sulfate) within the corneal stroma, keratocytes, and endothelium. This occurs due to a defect in the carbohydrate sulfotransferase 6 (CHST6) gene, leading to the production of undersulfated keratan sulfate. **Analysis of Incorrect Options:** * **Lattice Dystrophy (Option A):** Associated with the deposition of **Amyloid** fibrils. It stains with Congo Red and shows apple-green birefringence under polarized light. * **Granular Dystrophy (Option B):** Associated with the deposition of **Hyaline** material. It stains bright red with Masson Trichrome. * **Peripheral Dystrophy (Option D):** This is not a standard classification for the primary stromal dystrophies mentioned above. **High-Yield Clinical Pearls for NEET-PG:** To remember the stains and deposits for stromal dystrophies, use the mnemonic **"Marilyn Monroe Always Gets Her Men in L.A."**: 1. **M**acular – **M**ucopolysaccharide – **A**lcian Blue/Colloidal Iron. 2. **G**ranular – **H**yaline – **M**asson Trichrome. 3. **L**attice – **A**myloid – **C**ongo Red. * **Inheritance Note:** Macular dystrophy is the **least common** but the **most severe** stromal dystrophy and is the only one that is **Autosomal Recessive**. * **Extent:** In Macular dystrophy, the opacities extend up to the **limbus**, whereas in Granular and Lattice, the peripheral cornea usually remains clear.

Question 1

In Herpes zoster Keratitis, which of the following does NOT occur?

Accepted Answer

Sclerokeratitis

Answer

Pseudodendritic keratitis

Answer

Anterior stromal keratitis

Answer

Endothelitis

Question 2

Schwalbe's line represents the peripheral limit of which corneal layer?

Accepted Answer

Descemet's layer

Answer

Bowman's layer

Answer

Stroma

Answer

Endothelium

Question 3

Which of the following is true of a dendritic ulcer?

Accepted Answer

Caused by Herpes simplex virus

Answer

Topical corticosteroid given suppresses the symptoms

Answer

Oral acyclovir is effective in treatment

Answer

All of the above

Question 4

What happens to the corneal endothelium after injury?

Accepted Answer

Regenerates rapidly

Answer

Slowly regenerates

Answer

Never regenerates

Answer

Forms a scar

Question 5

K F Ring is seen in which condition?

Accepted Answer

Chalcosis

Answer

Sarcoidosis

Answer

Tuberous Sclerosis

Answer

VKH Syndrome

Question 6

Cogan's syndrome is associated with which of the following?

Accepted Answer

Keratitis

Answer

Conjunctivitis

Answer

Iritis

Answer

Myopia

Question 7

Schwalbe's line represents:

Accepted Answer

The termination of Descemet's membrane

Answer

The junction of the choroid and retina

Answer

The division between bulbar and palpebral conjunctiva

Answer

The upper limit of the macula

Question 8

Bowman's membrane is seen in which structure?

Accepted Answer

Cornea

Answer

Conjunctiva

Answer

Lens

Answer

Iris

Question 9

What is the initial treatment for a perforated corneal ulcer?

Accepted Answer

Tissue adhesive glue

Answer

Conjunctival flap grafting

Answer

Contact lens

Answer

Local anesthetic drops instillation

Question 10

Corneal dystrophy associated with acid mucopolysaccharidosis is:

Accepted Answer

Macular

Answer

Lattice

Answer

Granular

Answer

Peripheral

Diseases of the Cornea — MCQs

Diseases of the Cornea — MCQs

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