Diseases of the Cornea Practice Questions

Q: Which of the following is true regarding corneal dystrophy?

Bilateral. ### Explanation Corneal dystrophies are a group of genetic, non-inflammatory disorders characterized by the accumulation of abnormal material within the corneal layers. **Why "Bilateral" is the Correct Answer:** Corneal dystrophies are **hereditary** (mostly autosomal dominant) conditions. Because they are rooted in a genetic mutation present in all cells of the corneal tissue, they characteristically manifest as **bilateral, symmetrical, and slowly progressive** opacities. They typically appear in the first or second decade of life and are not associated with systemic diseases. **Why Other Options are Incorrect:** * **A. Inflammatory:** By definition, dystrophies are **non-inflammatory**. If inflammation (redness, pain, or cellular infiltration) is present, the diagnosis is more likely a corneal *degeneration* or *keratitis*. * **B. Neovascularization:** Corneal dystrophies are **avascular**. The cornea remains clear of blood vessels unless a secondary complication (like a persistent epithelial erosions or infection) occurs. Neovascularization is a hallmark of degenerations or chronic inflammatory states, not primary dystrophies. **High-Yield Clinical Pearls for NEET-PG:** * **Dystrophy vs. Degeneration:** Dystrophies are bilateral, central, and hereditary; Degenerations are often unilateral, peripheral, and associated with aging or inflammation. * **Most Common Dystrophy:** Fuchs’ Endothelial Corneal Dystrophy (FECD). * **Staining Mnemonics (Very High Yield):** * **M**any **A**mericans **G**et **R**ocky **M**ountains: **M**acular = **A**lcian Blue; **G**ranular = **R**odent (Masson) Trichrome; **L**attice = **M**any (Congo) Red. * **Layer Involvement:** * *Epithelial:* Meesmann’s. * *Stromal:* Granular, Macular, Lattice (Lattice is the most common stromal dystrophy). * *Endothelial:* Fuchs’, CHED (Congenital Hereditary Endothelial Dystrophy).

Q: Interstitial keratitis may be associated with which of the following conditions?

All of the above. **Explanation:** **Interstitial Keratitis (IK)** is a chronic non-ulcerative inflammation of the corneal stroma, characterized by cellular infiltration and vascularization without primary involvement of the epithelium or endothelium. It is typically an **immune-mediated response** to a systemic infection or inflammatory condition rather than a direct infection of the cornea. 1. **Congenital Syphilis (Option A):** This is the **most common cause** of IK (responsible for ~90% of cases historically). It typically presents bilaterally in late childhood or adolescence as part of the late manifestations of congenital syphilis. 2. **Malaria (Option B):** While rare, protozoal infections like Malaria and Leishmaniasis are documented systemic causes of IK. 3. **Sarcoidosis (Option C):** Non-infectious systemic granulomatous diseases, including Sarcoidosis and Cogan’s syndrome, are well-recognized etiologies of interstitial keratitis. Since all three conditions listed can trigger the immune-mediated stromal response characteristic of IK, **Option D (All of the above)** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Hutchinson’s Triad:** A classic sign of late congenital syphilis consisting of Interstitial Keratitis, Hutchinson’s teeth (notched incisors), and Sensorineural deafness (8th nerve deafness). * **Salmon Patch Appearance:** In the active stage of IK, deep vascularization gives the cornea a pinkish-orange hue. * **Ghost Vessels:** After the inflammation subsides, the cleared vessels remain as empty channels in the stroma, visible on slit-lamp examination. * **Wessely Ring:** An immune ring of precipitate often seen in the stroma during the acute phase. * **Other Causes:** Tuberculosis, Leprosy, Herpes Simplex (most common viral cause), and Lyme disease.

Q: Corneal diameter is increased in which of the following conditions?

All of the above. **Explanation:** The correct answer is **D. All of the above**, as each of these conditions involves an increase in the horizontal or overall corneal diameter, though the underlying mechanisms differ. 1. **Megalocornea:** This is a non-progressive, bilateral, X-linked recessive condition where the horizontal corneal diameter is **>13 mm** at birth or in adulthood. Importantly, the intraocular pressure (IOP) and corneal thickness are usually normal, distinguishing it from congenital glaucoma (buphthalmos). 2. **Keratoglobus:** This is a rare, non-inflammatory corneal ectasia where the entire cornea becomes extremely thin (especially at the periphery) and bulges forward in a **globular shape**. This protrusion leads to a significant increase in the measured corneal diameter and surface area. 3. **Keratoconus:** While primarily characterized by localized paracentral thinning and cone-shaped protrusion, advanced cases of keratoconus involve significant stretching of the corneal tissue. This ectasia results in an increased chord length and overall diameter of the cornea. **Clinical Pearls for NEET-PG:** * **Buphthalmos vs. Megalocornea:** In Buphthalmos (congenital glaucoma), the cornea is large (>12 mm before age 1) but is associated with **Haab’s striae** (tears in Descemet’s membrane) and raised IOP. Megalocornea has a clear cornea and normal IOP. * **Microcornea:** Defined as a diameter **<10 mm** at any age or **<9 mm** in a newborn. It is often associated with Nanophthalmos. * **Keratoglobus Risk:** Patients are at high risk of corneal perforation even with minor trauma due to extreme peripheral thinning. * **Normal Diameter:** The average adult horizontal corneal diameter is **11.7 mm**.

Q: Vortex keratopathy is seen with all the following drugs except:

Thioxanthines. **Explanation:** **Vortex Keratopathy (Cornea Verticillata)** is characterized by fine, golden-brown or greyish-white whorl-like opacities in the corneal epithelium. It occurs due to the deposition of drugs or their metabolites within the lysosomes of corneal epithelial cells (a form of drug-induced lipidosis). **Why Thioxanthines is the correct answer:** Thioxanthines (antipsychotics like Thiothixene) are primarily associated with **pigmentary deposits on the corneal endothelium and anterior lens capsule**, rather than the epithelial whorl patterns seen in vortex keratopathy. Therefore, it is the "except" in this list. **Analysis of Incorrect Options:** * **Phenothiazines:** Specifically **Chlorpromazine**, can cause vortex keratopathy, although it is more classically known for causing "star-shaped" anterior subcapsular cataracts and endothelial deposits. * **Tamoxifen:** This selective estrogen receptor modulator (SERM) used in breast cancer is a well-known cause of vortex keratopathy and crystalline retinopathy. * **Indomethacin:** This NSAID is a classic cause of whorl-like corneal deposits, which are usually dose-dependent and reversible upon discontinuation. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Vortex Keratopathy (CHAI-T):** **C**hloroquine/Hydroxychloroquine, **H**eamiodarone (Amiodarone - most common cause), **A**tovaquone, **I**ndomethacin, and **T**amoxifen. * **Fabry Disease:** The most important systemic (non-drug) cause of vortex keratopathy. If seen in a patient not on these medications, suspect an alpha-galactosidase A deficiency. * **Visual Impact:** Vortex keratopathy is usually asymptomatic and rarely affects visual acuity, thus drug discontinuation is seldom required unless systemic toxicity is suspected.

Q: Cornea verticillata is caused by which of the following medications?

Amiodarone. **Explanation:** **Cornea verticillata** (also known as vortex keratopathy) is characterized by fine, bilateral, golden-brown or greyish deposits in the corneal epithelium, typically arranged in a whorl-like pattern. **Why Amiodarone is correct:** Amiodarone is a Class III anti-arrhythmic drug known to cause lipidosis in the corneal epithelium. It binds to polar lipids, making them indigestible by lysosomal enzymes, leading to their accumulation. Nearly all patients on long-term amiodarone therapy develop these deposits. While they are usually asymptomatic and do not require discontinuation of the drug, they can occasionally cause visual halos or blurred vision. **Why other options are incorrect:** * **Erythromycin:** This is a macrolide antibiotic used topically for neonatal prophylaxis or bacterial conjunctivitis; it does not cause corneal deposits. * **Timolol:** A non-selective beta-blocker used to treat glaucoma. Its primary ocular side effects include stinging, dry eyes, and bradycardia, but not vortex keratopathy. * **Tetracycline:** While systemic tetracyclines can cause skin or tooth discoloration and are associated with pseudotumor cerebri, they do not cause the specific whorl-like corneal deposits seen in cornea verticillata. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Cornea Verticillata (CHAI-T):** **C**hloroquine/Hydroxychloroquine, **H**eavy metals (Gold, Iron), **A**miodarone, **I**ndomethacin, and **T**amoxifen. * **Fabry Disease:** This is the most important systemic condition associated with cornea verticillata (due to glycosphingolipid accumulation). * **Reversibility:** Amiodarone-induced deposits are typically reversible upon cessation of the drug, though this is rarely necessary.

Q: Which of the following types of corneal degeneration is most commonly seen in patients with trachoma?

Salzmann's nodular degeneration. **Explanation:** **Salzmann’s Nodular Degeneration (SND)** is the correct answer because it is a non-inflammatory condition characterized by the formation of bluish-white or greyish subepithelial nodules. It typically occurs as a late sequela to **chronic keratitis** or long-standing ocular surface inflammation. **Trachoma** is a leading cause of chronic keratoconjunctivitis, and the resulting chronic irritation and scarring predispose the cornea to these nodular deposits (composed of hyaline and collagen). **Analysis of Incorrect Options:** * **A. Terrien’s Disease:** This is a peripheral corneal thinning (marginal degeneration) characterized by vascularization, lipid deposition, and "gutter" formation. It is idiopathic and not typically associated with trachoma. * **B. Band Keratopathy:** This involves the deposition of calcium salts in the Bowman’s membrane. It is most commonly associated with chronic uveitis (especially in Juvenile Idiopathic Arthritis), hypercalcemia, or long-term silicone oil in the eye. * **C. Labrador Keratopathy (Spheroidal Degeneration):** Also known as Climatic Droplet Keratopathy, it is caused by chronic exposure to **UV radiation**, wind, and sand. It presents as amber-colored granules in the superficial stroma. **High-Yield Clinical Pearls for NEET-PG:** * **SND Appearance:** Nodules are often arranged in a circular fashion around the pupillary area or at the edge of old corneal scars. * **SND Management:** Usually asymptomatic; however, if vision is affected or irritation occurs, treatment involves superficial keratectomy or PTK (Phototherapeutic Keratectomy). * **Trachoma Association:** Remember the "SAFE" strategy for Trachoma (Surgery, Antibiotics, Facial cleanliness, Environmental improvement). SND is a late degenerative change, unlike the acute inflammatory signs like Herbert’s pits or Arlt’s line.

Q: Which corneal layer is responsible for deturgescence?

Endothelium. **Explanation:** The **corneal endothelium** is a single layer of hexagonal cells that plays a critical role in maintaining **corneal deturgescence**—the state of relative dehydration (approx. 78% water content) required for corneal transparency. It achieves this through two mechanisms: 1. **Active Endothelial Pump:** Na⁺/K⁺-ATPase pumps actively transport ions from the stroma into the aqueous humor, creating an osmotic gradient that draws water out. 2. **Leaky Barrier:** While it acts as a physical barrier, it allows controlled leakage of nutrients from the aqueous into the stroma. **Analysis of Incorrect Options:** * **Bowman’s Membrane (A):** An acellular, condensed layer of collagen. It provides structural integrity but has no metabolic or pumping function. It does not regenerate if damaged. * **Epithelium (C):** While the epithelium acts as a highly effective physical barrier to water (preventing tears from entering the stroma), it lacks the active metabolic "pump" capacity of the endothelium. * **Stroma (D):** The thickest layer (90%), composed of regularly arranged collagen fibrils. It is naturally hydrophilic (due to GAGs) and tends to swell; it is the *beneficiary* of deturgescence, not the cause. **High-Yield Clinical Pearls for NEET-PG:** * **Critical Cell Count:** Normal endothelial cell count is 2500–3000 cells/mm². If the count falls below **500 cells/mm²**, the pump fails, leading to corneal edema (Bullous Keratopathy). * **Regeneration:** Endothelial cells **do not regenerate** in vivo; they heal by enlargement and migration (pleomorphism and polymegethism). * **Specular Microscopy:** The gold standard investigation to assess endothelial cell density and morphology.

Question 1

Which of the following is true regarding corneal dystrophy?

Accepted Answer

Bilateral

Answer

Inflammatory

Answer

Neovascularization

Answer

All of the above

Question 2

Interstitial keratitis may be associated with which of the following conditions?

Accepted Answer

All of the above

Answer

Congenital syphilis

Answer

Malaria

Answer

Sarcoidosis

Question 3

Corneal diameter is increased in which of the following conditions?

Accepted Answer

All of the above

Answer

Megalocornea

Answer

Keratoglobus

Answer

Keratoconus

Question 4

Corneal transplantation requires which of the following procedures?

Accepted Answer

Specular microscopy is performed for corneal endothelial cell count.

Answer

Donor older than 60 years is not allowed.

Answer

The whole eye is preserved in culture.

Answer

HLA matching is a requirement.

Question 5

Vortex keratopathy is seen with all the following drugs except:

Accepted Answer

Thioxanthines

Answer

Phenothiazines

Answer

Tamoxifen

Answer

Indomethacin

Question 6

Cornea verticillata is caused by which of the following medications?

Accepted Answer

Amiodarone

Answer

Erythromycin

Answer

Timolol

Answer

Tetracycline

Question 7

Which of the following types of corneal degeneration is most commonly seen in patients with trachoma?

Accepted Answer

Salzmann's nodular degeneration

Answer

Terrien's disease

Answer

Band keratopathy

Answer

Labrador keratopathy

Question 8

Which corneal layer is responsible for deturgescence?

Accepted Answer

Endothelium

Answer

Bowman's membrane

Answer

Epithelium

Answer

Stroma

Question 9

Corneal ulceration may be caused by injury to which cranial nerve?

Accepted Answer

Fifth

Answer

Third

Answer

Sixth

Answer

All of the above

Question 10

Which of the following is NOT true for Mooren's ulcer?

Accepted Answer

Perforation of the cornea is a common complication.

Answer

It can be a type of peripheral ulcerative keratitis.

Answer

The advancing edge of the ulcer is typically undermined.

Answer

The floor of the ulcer is quickly vascularized.

Diseases of the Cornea — MCQs

Diseases of the Cornea — MCQs

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