Corneal Dystrophies — MCQs
Reis-Buckler dystrophy affects which layer of the cornea?
In congenital dystrophic variety of epidermolysis bullosa, mutation is seen in the gene coding for:
Which of the following statements about Fuchs' corneal dystrophy is true?
Which one of the following is an autosomal dominant disorder?
Statement 1 - A 59-year-old patient presents with flaccid bullae. Histopathology shows a suprabasal acantholytic split. Statement 2 - The row of tombstones appearance is diagnostic of Pemphigus vulgaris.
Match the following: A) Caplan syndrome- 1) Found first in coal worker B) Asbestosis- 2) Upper lobe predominance C) Mesothelioma- 3) Involves lower lobe D) Sarcoidosis- 4) Pleural effusion is seen
A 20-year-old male complains of repeated changes in glasses prescription. This is most likely caused by:
A 25 -year-old lady with past history of seeing colored haloes was watching a movie in a theater when she started having right eye pain. She started feeling nauseous and had to leave the movie midway due to vomiting. On examination she is found to have ciliary and conjunctival congestion and the pupil is vertically oval. The picture of the eye is given below. All are true about the condition shown except:
Which triad is seen after an acute attack of angle-closure glaucoma?
A patient, three years post-surgery, presents with the condition shown in the image and complains of decreased vision. What is the most likely diagnosis?
Corneal Dystrophies 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: In congenital dystrophic variety of epidermolysis bullosa, mutation is seen in the gene coding for:
- A. Laminin 4
- B. Keratin 14
- C. Collagen type 7 (Correct Answer)
- D. Alpha 6 integrin
Explanation: ***Correct: Collagen type 7*** - **Dystrophic epidermolysis bullosa** is characterized by defects in **collagen type 7**, which forms anchoring fibrils that connect the epidermis to the underlying dermal tissue. - Mutations in the gene *COL7A1* lead to fragile skin that **blisters easily** in the **dermo-epidermal junction** below the lamina densa (sublamina densa level). - This distinguishes it from other EB subtypes by its **sub-basement membrane zone** blistering. *Incorrect: Laminin 4* - Mutations in **laminin 332** (formerly laminin 5), not laminin 4, are associated with **junctional epidermolysis bullosa**, a different subtype. - Junctional EB primarily affects the **lamina lucida** within the dermo-epidermal junction. *Incorrect: Keratin 14* - Mutations in **keratin 5** and **keratin 14** are responsible for **epidermolysis bullosa simplex**, which involves blistering within the **basal layer of the epidermis**. - In this form, blisters occur *intraepidermally* above the basement membrane zone. *Incorrect: Alpha 6 integrin* - Mutations in **alpha 6 beta 4 integrin** subunits are also associated with **junctional epidermolysis bullosa**, specifically affecting the assembly of **hemidesmosomes**. - These defects lead to blistering within the **lamina lucida**, similar to laminin 332 mutations.
Question 3: Which of the following statements about Fuchs' corneal dystrophy is true?
- A. Glaucoma is not a common association.
- B. It is a type of endothelial dystrophy (Correct Answer)
- C. It is characterized by bilateral involvement
- D. It primarily occurs in older adults
Explanation: ***It is a type of endothelial dystrophy*** - **Fuchs' endothelial corneal dystrophy (FECD)** is the **classic posterior/endothelial corneal dystrophy**, classified in the **IC3D classification system** as a primary endothelial dystrophy. - It involves **progressive loss of corneal endothelial cells** and formation of **guttata** (excrescences in Descemet's membrane), leading to endothelial dysfunction. - The dysfunctional endothelium cannot maintain corneal deturgescence, resulting in **corneal edema** and eventually **bullous keratopathy** in advanced cases. *It is characterized by bilateral involvement* - While Fuchs' dystrophy is **typically bilateral**, it can be **asymmetric** in presentation and progression. - Bilaterality is a common feature but not the most defining characteristic of the disease. *It primarily occurs in older adults* - Fuchs' dystrophy typically manifests in **middle age (40s-50s)** and progresses with age. - However, the condition has a **genetic basis** and cellular changes begin earlier than symptom onset. - Symptomatic disease is more common in older adults, but this doesn't define the disease entity itself. *Glaucoma is not a common association* - Studies have shown **increased prevalence of glaucoma** in patients with Fuchs' dystrophy compared to the general population. - The association may relate to **endothelial dysfunction** affecting aqueous outflow or shared risk factors. - This statement is **false** - glaucoma association has been documented.
Question 4: Which one of the following is an autosomal dominant disorder?
- A. Cystic fibrosis
- B. Hereditary spherocytosis (Correct Answer)
- C. Sickle cell anemia
- D. G-6PD deficiency
Explanation: ***Hereditary spherocytosis*** - It is characterized by **autosomal dominant inheritance** [1], leading to the destruction of red blood cells. - Mutations in proteins that maintain the **red blood cell membrane** integrity result in spherocyte formation [1]. *Cystic fibrosis* - This condition follows a **autosomal recessive inheritance pattern**, requiring two copies of the mutated gene for disease manifestation. - It is caused by mutations in the **CFTR gene**, affecting chloride transport and leading to thick secretions. *G-6PD deficiency* - This disorder is inherited in an **X-linked recessive manner** [2], primarily affecting males and transmitted through carrier females. - Characterized by **hemolytic anemia** triggered by certain medications or infections, it does not follow dominant inheritance [2]. *Sickle cell anemia* - Sickle cell anemia is also an **autosomal recessive disorder** [3], meaning affected individuals must inherit two copies of the sickle cell gene. - It results in a mutation in the **HBB gene**, leading to the production of abnormal hemoglobin (HbS) [3].
Question 5: Statement 1 - A 59-year-old patient presents with flaccid bullae. Histopathology shows a suprabasal acantholytic split. Statement 2 - The row of tombstones appearance is diagnostic of Pemphigus vulgaris.
- A. Statements 1 & 2 are correct, 2 is not explaining 1 (Correct Answer)
- B. Statements 1 and 2 are correct and 2 is the correct explanation for 1
- C. Statements 1 and 2 are incorrect
- D. Statement 1 is incorrect
Explanation: ***Correct: Statements 1 & 2 are correct, 2 is not explaining 1*** **Analysis of Statement 1:** - A 59-year-old patient with **flaccid bullae** and **suprabasal acantholytic split** on histopathology is the classic presentation of **Pemphigus vulgaris** - The flaccid (easily ruptured) nature of bullae distinguishes it from tense bullae seen in bullous pemphigoid - The suprabasal location of the split (just above the basal layer) with acantholysis (loss of cell-to-cell adhesion) is pathognomonic - **Statement 1 is CORRECT** ✓ **Analysis of Statement 2:** - The **"row of tombstones" or "tombstone appearance"** is indeed a diagnostic histopathological feature of Pemphigus vulgaris - This appearance results from basal keratinocytes remaining attached to the basement membrane while suprabasal cells separate due to acantholysis - The intact basal cells standing upright resemble a row of tombstones - **Statement 2 is CORRECT** ✓ **Does Statement 2 explain Statement 1?** - Statement 2 describes a **histopathological appearance** (tombstone pattern) that is a **consequence** of the suprabasal split - However, it does NOT explain the **underlying cause** of the flaccid bullae or the suprabasal split - The true explanation involves **IgG autoantibodies against desmoglein 3 (and desmoglein 1)**, which attack intercellular adhesion structures (desmosomes), causing **acantholysis** - Therefore, **Statement 2 does NOT explain Statement 1** ✗ *Incorrect: Statement 2 is the correct explanation for Statement 1* - While both statements describe features of Pemphigus vulgaris, the tombstone appearance is a descriptive finding, not an explanatory mechanism *Incorrect: Statements 1 and 2 are incorrect* - Both statements are medically accurate descriptions of Pemphigus vulgaris features *Incorrect: Statement 1 is incorrect* - Statement 1 correctly describes the cardinal clinical and histopathological features of Pemphigus vulgaris
Question 6: Match the following: A) Caplan syndrome- 1) Found first in coal worker B) Asbestosis- 2) Upper lobe predominance C) Mesothelioma- 3) Involves lower lobe D) Sarcoidosis- 4) Pleural effusion is seen
- A. A-3, B-4, C-2, D-1
- B. A-1, B-4, C-3, D-2 (Correct Answer)
- C. A-4, B-2, C-3, D-1
- D. A-2, B-4, C-3, D-1
Explanation: **A-1, B-4, C-3, D-2** - **Caplan syndrome** was first described in **coal workers** with **rheumatoid arthritis** and progressive massive fibrosis. - **Asbestosis** is often associated with **pleural effusion**, which can be benign or malignant. - **Mesothelioma** typically involves the **lower lobes** of the lungs, specifically the pleura, and is strongly linked to asbestos exposure. - **Sarcoidosis** is characterized by **non-caseating granulomas**, which have a predilection for the **upper lobes** of the lungs. *A-3, B-4, C-2, D-1* - This option incorrectly states that Caplan syndrome involves the lower lobe; **Caplan syndrome** is defined by the presence of large nodules in the lungs of coal workers with rheumatoid arthritis, and their specific lobar distribution is not a defining characteristic. - This option incorrectly states that Mesothelioma has an upper lobe predominance; **Mesothelioma** is a pleural malignancy and typically involves the **lower lobes**, extending along the pleura. *A-4, B-2, C-3, D-1* - This option incorrectly associates Caplan syndrome with pleural effusion; **Caplan syndrome** manifests as rheumatoid nodules in the lungs, not primarily pleural effusion. - This option incorrectly states that Asbestosis has an upper lobe predominance; **Asbestosis** predominantly affects the **lower lobes** of the lungs, causing interstitial fibrosis. *A-2, B-4, C-3, D-1* - This option incorrectly states that Caplan syndrome has an upper lobe predominance; the defining feature of **Caplan syndrome** is the combination of rheumatoid arthritis and pneumoconiosis, not specific lobar involvement. - This option correctly identifies pleural effusion with asbestosis and lower lobe involvement with mesothelioma, but **Caplan syndrome** is not characterized by upper lobe predominance.
Question 7: A 20-year-old male complains of repeated changes in glasses prescription. This is most likely caused by:
- A. Keratoconus (Correct Answer)
- B. Cataract
- C. Glaucoma
- D. Pathological myopia
Explanation: ***Keratoconus*** - **Keratoconus** is a progressive disorder where the cornea thins and protrudes into a cone shape, leading to irregular astigmatism and frequent changes in glasses prescription. - This condition commonly presents in young adults and is characterized by **rapid, repeated changes** in both spherical and cylindrical components due to progressive corneal distortion. - The irregular corneal shape makes it difficult to achieve stable, satisfactory vision correction with glasses alone. *Cataract* - A **cataract** is a clouding of the eye's natural lens, which causes blurred vision, glare, and difficulty seeing at night. - While it can cause a "myopic shift" leading to prescription changes, it is more common in older individuals (>50 years) and the changes are typically slower and less frequent than in keratoconus. *Glaucoma* - **Glaucoma** is a group of eye conditions that damage the optic nerve, often due to high intraocular pressure, leading to peripheral vision loss and eventually blindness. - It does not cause changes in refractive error or require frequent updates to glasses prescriptions. - Visual changes are related to field defects, not refractive changes. *Pathological myopia* - **Pathological myopia** is a severe form of nearsightedness where the eye elongates excessively, leading to progressive increases in myopic refractive error. - While it can cause prescription changes in young adults, the progression is typically more **gradual and predictable** (mainly increasing spherical myopia) compared to the **rapid, irregular changes** seen in keratoconus. - Keratoconus is distinguished by frequent changes in astigmatism due to irregular corneal shape, whereas pathological myopia mainly affects spherical power.
Question 8: A 25 -year-old lady with past history of seeing colored haloes was watching a movie in a theater when she started having right eye pain. She started feeling nauseous and had to leave the movie midway due to vomiting. On examination she is found to have ciliary and conjunctival congestion and the pupil is vertically oval. The picture of the eye is given below. All are true about the condition shown except:
- A. Loss of iris pattern
- B. Steamy insensitive cornea
- C. Absent reaction to light and accommodation
- D. Present PL (Correct Answer)
Explanation: ***Present PL (Perception of Light)*** - In **acute angle-closure glaucoma (AACG)**, visual acuity is typically severely reduced due to corneal edema and elevated intraocular pressure, but **perception of light (PL) is usually preserved** in acute presentations. - While vision may be reduced to counting fingers or hand movements, **complete loss of light perception is uncommon** unless there is severe, prolonged attack with irreversible optic nerve damage. - All other features listed (loss of iris pattern, steamy cornea, absent pupillary reactions) are **consistently present** in AACG, whereas PL can be variable but is typically **present initially**. - This makes "Present PL" the **correct answer** as it is the statement that is **NOT always/universally true** - though PL is often present, the question implies it as a definitive feature when it's actually variable. *Loss of iris pattern* - This is a **consistent finding** in AACG during an acute attack. - The iris becomes **edematous** due to elevated intraocular pressure (often >40 mmHg), which obscures the normal radial folds and crypts. - The iris appears dull, muddy, and featureless - a key diagnostic sign. *Steamy insensitive cornea* - The markedly elevated intraocular pressure causes **corneal epithelial and stromal edema**. - This produces a **hazy or "steamy" appearance** that interferes with visualization of anterior chamber structures. - Corneal sensation may be reduced due to epithelial edema and ischemia. *Absent reaction to light and accommodation* - The pupil in AACG is characteristically **fixed and mid-dilated (4-6 mm)**, often vertically oval as described. - **Complete absence of pupillary light reflex** (both direct and consensual) occurs due to iris sphincter ischemia. - **No accommodation response** due to the fixed, dilated pupil and compromised iris function.
Question 9: Which triad is seen after an acute attack of angle-closure glaucoma?
- A. Gaucher triad
- B. Virchow triad
- C. Vogt's triad (Correct Answer)
- D. Hutchinson's triad
Explanation: ***Vogt's triad*** - **Vogt's triad** refers to the classical findings seen after an acute attack of **angle-closure glaucoma**. - The triad consists of: **glaukomflecken** (anterior subcapsular lens opacities from ischemic necrosis of lens epithelium), **iris stromal atrophy** (sectoral iris atrophy in the area of ischemia), and **fixed mid-dilated pupil** (due to iris sphincter damage). - These signs indicate **ischemic damage** to the anterior segment following the acute episode of elevated intraocular pressure. *Gaucher triad* - **Gaucher triad** refers to the characteristic systemic symptoms of **Gaucher disease**, an inherited lipid storage disorder. - It involves **hepatosplenomegaly**, **bone pain**, and **thrombocytopenia**, which are unrelated to glaucoma. *Virchow triad* - The **Virchow triad** describes the three main factors contributing to **thrombus formation**: **stasis** of blood flow, **endothelial injury**, and **hypercoagulability**. - This triad is relevant to cardiovascular pathology, not the effects of angle-closure glaucoma. *Hutchinson's triad* - **Hutchinson's triad** is a set of symptoms associated with **congenital syphilis**. - It includes **interstitial keratitis**, **Hutchinson's teeth**, and **eighth nerve deafness**, which are entirely distinct from ocular hypertension.
Question 10: A patient, three years post-surgery, presents with the condition shown in the image and complains of decreased vision. What is the most likely diagnosis?
- A. Corneal Dystrophy
- B. Posterior Subcapsular Cataract (PSC)
- C. Pseudophakic Bullous Keratopathy
- D. Posterior Capsular Opacification (Correct Answer)
Explanation: ***Posterior Capsular Opacification*** - The image (especially part B, the **red reflex view**) shows a cloudy membrane with **Elschnig pearls** and fibrous tissue behind the intraocular lens, which is characteristic of **PCO**. - PCO commonly occurs months to years after cataract surgery and causes **decreased vision** due to scattering of light. *Corneal Dystrophy* - Corneal dystrophies primarily affect the **cornea**, leading to various forms of corneal opacification, and would typically appear as cloudiness or irregularities within the corneal layers. - While it can cause decreased vision, the opacification seen in the image is clearly behind the iris plane and involves the posterior capsule, not the cornea. *Pseudophakic Bullous Keratopathy* - This condition involves **corneal edema** and **bullae formation** due to endothelial cell dysfunction, leading to a hazy cornea. - The image does not show corneal edema or bullae; instead, the primary pathology is located at the **posterior capsule** of the intraocular lens. *Posterior Subcapsular Cataract (PSC)* - A PSC is a type of cataract that forms **before cataract surgery** and affects the natural crystalline lens. - The patient is three years post-surgery, indicating that the natural lens has been replaced, making a PSC (of the natural lens) an impossible diagnosis in this context.
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