Corneal Degenerations — MCQs
Reis-Buckler dystrophy affects which layer of the cornea?
Which of the following is NOT a cause of crystal keratopathy?
What condition is associated with copper deposition in the cornea?
What is the most common cause of corneal neovascularization in developed countries?
Identify the diagnosis based on the clinical image shown.
Which of the following features is characteristic of a fungal corneal ulcer?
A 76-year-old female presents with difficulty reading. Bilateral white opacifications consistent with cataract formation are observed. In which structure are these opacifications located?
In a child with juvenile idiopathic arthritis, the eye examination shows presence of:
What does the following image show?
Corneal vascularization is caused by which of the following?
Corneal Degenerations Indian Medical PG Practice Questions and MCQs
Question 1: Reis-Buckler dystrophy affects which layer of the cornea?
- A. Stroma
- B. Bowman's membrane (Correct Answer)
- C. Endothelium
- D. Epithelium
Explanation: ***Bowman's membrane*** - **Reis-Buckler dystrophy** is a type of corneal dystrophy specifically characterized by the progressive destruction and irregular regeneration of **Bowman's membrane** and the superficial stroma. - This leads to the formation of an abnormal fibrous layer that causes recurrent corneal erosions and significant visual impairment due to corneal opacification. *Epithelium* - While patients often experience recurrent **corneal erosions** involving the epithelium, the primary pathology in Reis-Buckler dystrophy affects the underlying Bowman's membrane. - The epithelial damage is secondary to the irregular surface created by the diseased Bowman's layer. *Stroma* - The **stroma** can be secondarily affected with superficial scarring and opacification in Reis-Buckler dystrophy, but the initial and primary site of pathology is Bowman's membrane. - Other dystrophies, such as macular or granular dystrophies, primarily involve the corneal stroma. *Endothelium* - The **endothelium** is not directly affected in Reis-Buckler dystrophy. - Endothelial dystrophies, such as Fuchs' endothelial dystrophy, involve the innermost layer of the cornea and lead to corneal edema.
Question 2: 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 3: What condition is associated with copper deposition in the cornea?
- A. Keratoglobus
- B. Keratoconus
- C. Siderosis
- D. Wilson's disease (Correct Answer)
Explanation: ***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.
Question 4: What is the most common cause of corneal neovascularization in developed countries?
- A. Hypoxia from contact lens use (Correct Answer)
- B. Transplant rejection
- C. Viral infection
- D. All of the options
Explanation: ***Hypoxia from contact lens use*** - **Chronic or severe corneal hypoxia** due to prolonged or improper contact lens wear is the **most frequent cause** of corneal neovascularization in developed countries. - The cornea, being avascular, depends on atmospheric oxygen. When deprived, it attempts to compensate by growing new blood vessels from the limbal arcade. - This is particularly common with **extended-wear contact lenses**, poorly fitting lenses, or **overwear syndrome** that restricts oxygen transmission to the cornea. - Modern **high-Dk (oxygen permeability) lenses** have reduced this complication, but it remains the leading cause. *Transplant rejection* - While corneal transplant rejection can cause inflammation and neovascularization, it affects only the **post-keratoplasty population**, making it far less common as an overall cause. - Rejection typically presents with **epithelial or stromal edema**, keratic precipitates, and graft clouding, with neovascularization being a secondary feature. *Viral infection* - Viral infections, particularly **herpes simplex keratitis**, can cause **significant corneal neovascularization** through chronic inflammation and stromal damage. - While HSV keratitis is an important cause, especially in recurrent cases, contact lens-related hypoxia affects a much larger population in developed countries. *All of the options* - While transplant rejection and viral infection can lead to corneal neovascularization, **hypoxia from contact lens use is the most prevalent cause** in modern clinical practice in developed countries. - The other options represent important but less frequent causes or affect smaller patient populations.
Question 5: Identify the diagnosis based on the clinical image shown.
- A. Horner-Trantas spots
- B. Herbert's pits (Correct Answer)
- C. Pannus
- D. Corneal dystrophy
Explanation: ***Herbert's pits*** - The image displays characteristic **pits at the limbus**, which are a hallmark of healed follicular conjunctivitis, specifically **Herbert's pits**. - These pits are pathognomonic for **trachoma**, a chronic keratoconjunctivitis caused by *Chlamydia trachomatis*. *Horner-Trantas spots* - These are small, raised, gelatinous white dots found at the limbus, typically containing **eosinophils**. - They are characteristic of **vernal keratoconjunctivitis**, an allergic inflammatory condition, and not seen in the provided image. *Pannus* - **Pannus** refers to the growth of **vascularized connective tissue** onto the cornea. - While pannus is also a feature of trachoma, the image specifically shows distinct limbal pits, rather than diffuse vascularization. *Corneal dystrophy* - **Corneal dystrophies** are a group of inherited, bilateral, and progressive corneal disorders that manifest as opacities or structural changes in the cornea. - The findings in the image, such as pits, are inflammatory in origin and distinct from the typically stromal or epithelial changes seen in corneal dystrophies.
Question 6: Which of the following features is characteristic of a fungal corneal ulcer?
- A. The ulcer has feathery margins. (Correct Answer)
- B. Symptoms are more prominent than signs.
- C. The ulcer appears dry and grayish-white.
- D. The ulcer is associated with diffuse corneal edema.
Explanation: ***The ulcer has feathery margins.*** - **Feathery margins** with satellite lesions are the **most characteristic feature** of fungal corneal ulcers, representing fungal hyphae spreading through the corneal stroma in a branching pattern - This infiltrative pattern with irregular, feathery borders is considered **pathognomonic** for fungal keratitis and is a key diagnostic feature - The feathery appearance helps distinguish fungal from bacterial ulcers clinically *The ulcer appears dry and grayish-white.* - While fungal ulcers can have a dry, grayish-white appearance, this is **less specific** and can be seen in other conditions - This feature is supportive but not as characteristic as the feathery margins - The texture relates to the minimal suppuration typical of fungal infections *The ulcer is associated with diffuse corneal edema.* - Diffuse corneal edema is more characteristic of **severe bacterial keratitis** or endothelial dysfunction - Fungal ulcers typically have more **localized infiltrates** with relatively less surrounding edema - When edema occurs, it's usually proportionate to the depth of infiltration *Symptoms are more prominent than signs.* - This describes **viral keratitis** (especially herpes simplex), where severe pain and photophobia occur with subtle signs - In **fungal ulcers**, the visible signs are usually **prominent** and correlate well with symptom severity - The lesion itself is typically quite evident on examination
Question 7: A 76-year-old female presents with difficulty reading. Bilateral white opacifications consistent with cataract formation are observed. In which structure are these opacifications located?
- A. Aqueous humor
- B. Cornea
- C. Lens (Correct Answer)
- D. Optic nerve
Explanation: ***Lens*** - **Cataracts** are defined by the **clouding of the natural lens** of the eye, which causes blurred vision and difficulty with activities like reading. - The condition is very common, especially among older adults, and affects the **bilateral vision** as described in the case. *Aqueous humor* - The **aqueous humor** is a clear fluid that fills the space between the cornea and the lens; it is not the structure that becomes opaque in cataracts. - Problems with aqueous humor are typically associated with glaucoma (due to increased intraocular pressure) rather than cataract formation. *Cornea* - The **cornea** is the transparent outer layer of the eye that helps focus light, but it does not develop cataracts. - Opacities in the cornea (e.g., from injuries or infections) would be described differently and produce different visual symptoms. *Optic nerve* - The **optic nerve** transmits visual information from the retina to the brain; it is a nerve, not a structure where light focuses or where cataracts develop. - Damage to the optic nerve typically leads to vision loss or blind spots, not blurred vision from opacification.
Question 8: In a child with juvenile idiopathic arthritis, the eye examination shows presence of:
- A. Band keratopathy (Correct Answer)
- B. Vortex keratopathy
- C. Fuchs' endothelial dystrophy
- D. Bitot's spots
Explanation: ***Band keratopathy*** - **Band keratopathy** is a common ocular manifestation in children with chronic uveitis secondary to **juvenile idiopathic arthritis (JIA)**, characterized by a horizontal band-like deposition of calcium salts in the superficial cornea. - The image depicts a whitish or grayish band across the cornea, consistent with **calcium deposition**, which is a hallmark of band keratopathy. *Vortex keratopathy* - **Vortex keratopathy** (or **cornea verticillata**) is a swirling, whorl-like pattern of corneal deposits, typically caused by drug toxicity (e.g., amiodarone, chloroquine) or metabolic disorders (e.g., Fabry disease). - It does not present as a horizontal band or diffuse opacification like that seen in the image, and is unrelated to JIA. *Fuchs' endothelial dystrophy* - **Fuchs' endothelial dystrophy** is a unilateral or bilateral progressive condition primarily affecting the corneal endothelium, leading to stromal edema and **guttae** (small excrescences on Descemet's membrane). - It typically affects older adults and is not primarily linked to JIA or the appearance in the provided image. *Bitot's spots* - **Bitot's spots** are foamy, triangular patches of keratinized conjunctival epithelium, usually located on the temporal bulbar conjunctiva, and are pathognomonic for **vitamin A deficiency**. - They are a conjunctival finding, not a corneal one, and are not associated with JIA.
Question 9: What does the following image show?
- A. Anterior uveitis
- B. Membranous conjunctivitis
- C. Pannus (Correct Answer)
- D. Pseudomembranous conjunctivitis
Explanation: ***Pannus*** - The image distinctly shows **new blood vessels growing into the cornea** from the limbus, which is characteristic of pannus formation. This vascularization often accompanies chronic inflammation or hypoxia. - This condition is a hallmark of certain ophthalmic diseases, such as **trachoma** or chronic irritation from prolonged **contact lens wear**. *Anterior uveitis* - Anterior uveitis presents with inflammation of the iris and ciliary body, typically causing **ciliary flush**, **miosis**, and cells/flare in the anterior chamber, which are not the primary features shown. - While uveitis can sometimes lead to corneal changes, the prominent **vascularization extending onto the cornea** is not its defining visual characteristic. *Membranous conjunctivitis* - Membranous conjunctivitis is characterized by the formation of a **true membrane on the conjunctiva** that binds tightly to the underlying epithelium, often caused by severe bacterial infections like *Corynebacterium diphtheriae*. - The image does not show a membrane on the conjunctival surface; instead, it highlights **corneal vascularization**. *Pseudomembranous conjunctivitis* - Pseudomembranous conjunctivitis involves a **fibrinous exudate loosely adherent** to the conjunctiva, which can be peeled off without significant bleeding, as seen in adenoviral conjunctivitis. - The findings in the image, specifically **vascular ingrowth into the cornea**, are not consistent with the appearance of a pseudomembrane on the conjunctiva.
Question 10: Corneal vascularization is caused by which of the following?
- A. Graft rejection
- B. Chemical burn
- C. Contact lens use
- D. All of the above (Correct Answer)
Explanation: **Explanation:** Corneal vascularization (neovascularization) is a pathological condition where new blood vessels grow into the normally avascular cornea. This occurs when the balance between angiogenic factors (like VEGF) and anti-angiogenic factors is disrupted, usually due to inflammation, hypoxia, or limbal stem cell deficiency. **Analysis of Options:** * **Graft Rejection (Option A):** This is an inflammatory immune response. Neovascularization is both a risk factor for and a sign of corneal graft rejection. Vessels provide a pathway for immune cells to reach the donor tissue, leading to an "immune attack." * **Chemical Burn (Option B):** Alkali burns are particularly notorious. They cause extensive limbal stem cell damage and severe inflammation. The loss of the limbal barrier allows conjunctival vessels to encroach upon the cornea (conjunctivalization). * **Contact Lens Use (Option C):** Chronic use, especially with low-permeability lenses or overwear, leads to **corneal hypoxia**. The lack of oxygen triggers the release of vasoproliferative factors, causing superficial or deep stromal vessels to grow from the limbus. Since all three conditions are well-established causes of corneal neovascularization, **Option D** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Pannus:** This refers to superficial vascularization accompanied by infiltration of granulation tissue (commonly seen in Trachoma and Phlyctenular keratoconjunctivitis). * **Micropannus:** Defined as vessel growth <2mm beyond the limbus (common in Trachoma). * **Ghost Vessels:** These are non-perfused, empty vascular channels that remain after the inciting inflammatory stimulus has subsided (classic in interstitial keratitis/Syphilis). * **Management:** Topical steroids or NSAIDs are used to reduce inflammation; anti-VEGF agents (e.g., Bevacizumab) are emerging treatments.
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