Diseases of the Conjunctiva — MCQs

Diseases of the Conjunctiva Indian Medical PG Practice Questions and MCQs

Question 51: What is the cause of blindness in pterygium?

A. Astigmatism (Correct Answer)
B. Loss of visual axis
C. Cataract
D. Limitation of ocular movements

Explanation: **Explanation:** A **pterygium** is a triangular, fibrovascular proliferation of the subconjunctival tissue that encroaches onto the cornea. **1. Why Astigmatism is the correct answer:** The primary cause of visual impairment in the early to moderate stages of pterygium is **With-the-Rule (WTR) astigmatism**. The advancing head of the pterygium exerts mechanical traction on the cornea, causing it to flatten in the horizontal meridian. This induced corneal irregularity leads to a significant decrease in visual acuity even before the lesion reaches the pupillary area. **2. Analysis of Incorrect Options:** * **B. Loss of visual axis:** While a pterygium can eventually grow over the pupillary area and block the visual axis, this is a late-stage complication. Astigmatism occurs much earlier and is the more common clinical cause of blurred vision. * **C. Cataract:** Pterygium is a surface ocular disease and does not involve the lens; there is no direct causal link to cataract formation. * **D. Limitation of ocular movements:** Large or recurrent pterygia can cause symblepharon or fibrosis, leading to restricted motility (usually in abduction), but this causes **diplopia**, not blindness. **Clinical Pearls for NEET-PG:** * **Stockers Line:** An iron deposit (hemosiderin) seen on the corneal epithelium at the leading edge of a stable pterygium. * **Indications for Surgery:** Visual impairment (due to astigmatism or axis obstruction), cosmetic disfigurement, or documented rapid growth. * **Gold Standard Treatment:** Surgical excision with **Limbal Conjunctival Autograft (CAG)** to minimize the high recurrence rate. * **Fuchs’ Flecks:** Small greyish-white opacities seen at the head of the pterygium.

Question 52: Phlyctenular keratoconjunctivitis is due to hypersensitivity to which of the following allergens?

A. Pollen
B. Chemicals
C. Mycobacterium tuberculosis proteins (Correct Answer)
D. Animal fur

Explanation: **Explanation:** **Phlyctenular Keratoconjunctivitis** is a localized **Type IV (Delayed) Hypersensitivity reaction** of the conjunctiva and cornea to endogenous microbial proteins to which the patient has been previously sensitized. **Why Option C is Correct:** Historically and most commonly in developing countries like India, the most frequent allergen is **Tuberculoprotein** (derived from *Mycobacterium tuberculosis*). Other common triggers include *Staphylococcus aureus* (cell wall proteins), and rarely, *Moraxella axenfeld* or fungal antigens like *Candida albicans*. The "phlycten" represents a lymphocytic infiltration in the subepithelial layer. **Why Other Options are Incorrect:** * **Options A & D (Pollen and Animal fur):** These are common triggers for **Type I (Immediate) Hypersensitivity** reactions, such as Seasonal Allergic Conjunctivitis (SAC) or Vernal Keratoconjunctivitis (VKC), characterized by IgE-mediated mast cell degranulation and itching. * **Option B (Chemicals):** These typically cause **Toxic Conjunctivitis** or direct chemical burns, which are irritant-mediated rather than a specific delayed hypersensitivity response to microbial proteins. **High-Yield Clinical Pearls for NEET-PG:** * **The Phlycten:** A characteristic pinkish-white nodule surrounded by a localized zone of hyperemia. It typically moves from the limbus toward the center of the cornea. * **Fascicular Ulcer:** A wandering corneal ulcer that carries a leash of blood vessels behind it; it is a classic complication of phlyctenular keratitis. * **Symptoms:** Intense photophobia (especially when the cornea is involved), lacrimation, and blepharospasm. * **Management:** Topical steroids for the ocular lesion, but it is **mandatory** to rule out systemic Tuberculosis (via Chest X-ray and Mantoux test) or treat associated staphylococcal blepharitis.

Question 53: Acute hemorrhagic conjunctivitis is caused by which of the following agents?

A. Enterovirus (Correct Answer)
B. Adenovirus
C. Pseudomonas
D. Streptococcus haemolyticus

Explanation: **Explanation:** **Acute Hemorrhagic Conjunctivitis (AHC)** is a highly contagious, self-limiting viral infection characterized by sudden onset, painful conjunctival inflammation, and prominent subconjunctival hemorrhages. 1. **Why Enterovirus is Correct:** The primary etiological agents for AHC are **Enterovirus 70** and **Coxsackievirus A24**. These are small RNA viruses. Enterovirus 70 is particularly notorious for causing large-scale epidemics (often called "Apollo Conjunctivitis" as it was first described during the Apollo 11 mission era in 1969). The hallmark of this infection is the rapid appearance of petechial hemorrhages that coalesce into large subconjunctival bleeds. 2. **Why Incorrect Options are Wrong:** * **Adenovirus:** While Adenoviruses (specifically types 8, 19, and 37) cause **Epidemic Keratoconjunctivitis (EKC)**, they typically present with pseudomembranes and corneal subepithelial infiltrates rather than the frank, widespread hemorrhages seen in AHC. * **Pseudomonas:** This is a gram-negative bacterium that causes aggressive **bacterial keratitis** (corneal ulcers), often associated with contact lens wear. It presents with a characteristic greenish-yellow discharge, not primary hemorrhagic conjunctivitis. * **Streptococcus haemolyticus:** This can cause acute mucopurulent conjunctivitis or pseudomembranous conjunctivitis, but it is not the causative agent for the specific clinical entity of AHC. **High-Yield Clinical Pearls for NEET-PG:** * **Incubation Period:** Very short (12–48 hours). * **Neurological Association:** Enterovirus 70 is rarely associated with a polio-like **radiculomyelitis** (lower motor neuron paralysis). * **Transmission:** Highly contagious via hand-to-eye contact and fomites. * **Management:** Supportive treatment only; steroids are generally contraindicated as they may prolong viral shedding.

Question 54: Leber cells are most commonly seen in which of the following conditions?

A. Vernal keratoconjunctivitis
B. Phlyctenular conjunctivitis
C. Ophthalmia neonatorum
D. Trachoma (Correct Answer)

Explanation: **Explanation:** **Trachoma** (caused by *Chlamydia trachomatis* serotypes A, B, Ba, and C) is a chronic keratoconjunctivitis characterized by a mixed follicular and papillary response. **Leber cells** are large, multinucleated macrophages containing phagocytosed debris (necrotic material). They are found within the follicles of Trachoma. Their presence indicates follicular necrosis, which is a hallmark of the disease and eventually leads to the characteristic scarring (Arlt’s line). **Analysis of Incorrect Options:** * **A. Vernal Keratoconjunctivitis (VKC):** This is a Type I IgE-mediated hypersensitivity reaction. The predominant cells are **eosinophils** and mast cells. Characteristic findings include "cobblestone" papillae and Horner-Trantas dots. * **B. Phlyctenular Conjunctivitis:** This is a Type IV delayed hypersensitivity reaction to endogenous antigens (most commonly Tubercular protein). It is characterized by a "phlycten" (a small nodule) consisting of a perivascular cuff of **lymphocytes**. * **C. Ophthalmia Neonatorum:** This is acute conjunctivitis in a newborn. Depending on the etiology (e.g., *N. gonorrhoeae*), it typically presents with a massive **purulent discharge** and polymorphonuclear leucocytes, not necrotic follicles. **High-Yield Clinical Pearls for NEET-PG:** * **H. P. Bodies (Halberstaedter-Prowazek):** Intracytoplasmic inclusion bodies seen in Trachoma (epithelial cells). * **Herbert’s Pits:** Scarred-down limbal follicles, pathognomonic for Trachoma. * **SAFE Strategy:** WHO-recommended management (Surgery, Antibiotics, Facial cleanliness, Environmental improvement). * **Drug of Choice:** Single dose of Oral Azithromycin (20 mg/kg).

Question 55: Epidemic conjunctivitis is reported in a rural area. What is the most probable causative organism?

A. Adenovirus (Correct Answer)
B. Herpes virus
C. EB virus
D. Papilloma virus

Explanation: **Explanation:** **Adenovirus** is the most common cause of viral conjunctivitis worldwide and is the primary agent responsible for outbreaks of **Epidemic Keratoconjunctivitis (EKC)**. It is highly contagious, often spreading through respiratory droplets, contaminated fingers, or ophthalmic instruments (like tonometers). EKC is typically caused by **Adenovirus serotypes 8, 19, and 37**. It presents with sudden onset follicular conjunctivitis, preauricular lymphadenopathy, and characteristic subepithelial corneal infiltrates. **Why other options are incorrect:** * **Herpes Simplex Virus (HSV):** Usually causes unilateral blepharoconjunctivitis or keratitis (dendritic ulcers) rather than large-scale epidemics. * **Epstein-Barr Virus (EBV):** While it can cause follicular conjunctivitis or Parinaud’s oculoglandular syndrome, it is a rare cause and does not present as an epidemic. * **Papilloma Virus:** Primarily causes benign conjunctival papillomas (warts) rather than acute infectious conjunctivitis. **High-Yield Clinical Pearls for NEET-PG:** 1. **Pharyngoconjunctival Fever (PCF):** Also caused by Adenovirus (serotypes 3, 4, 7). It presents as a triad of fever, pharyngitis, and follicular conjunctivitis (often seen in children/swimming pools). 2. **Transmission:** The virus can survive on dry surfaces for weeks; strict hand hygiene is the most important preventive measure. 3. **Hemorrhagic Conjunctivitis:** If the question mentions "Acute Hemorrhagic Conjunctivitis" (AHC) in an epidemic, consider **Enterovirus 70** or **Coxsackievirus A24**. 4. **Treatment:** Primarily supportive (cold compresses, artificial tears). Topical steroids are reserved for severe subepithelial infiltrates affecting vision.

Question 56: A 6-year-old unvaccinated child presents with acute membranous conjunctivitis. Which of the following is TRUE about acute membranous conjunctivitis?

A. The membrane is easy to peel.
B. Peeling the membrane can cause bleeding. (Correct Answer)
C. Diphtheria causes a false membrane.
D. The membrane cannot be removed.

Explanation: **Explanation:** **1. Why Option B is Correct:** Acute membranous conjunctivitis is characterized by the formation of a **true membrane** on the palpebral conjunctiva. This occurs when the inflammatory exudate is rich in fibrin, which coagulates not just on the surface, but also involves the **superficial layers of the conjunctival epithelium**. Because the membrane is structurally integrated with the underlying tissue, any attempt to peel it off results in the tearing of the epithelium and small capillaries, leading to a **raw, bleeding surface**. **2. Analysis of Incorrect Options:** * **Option A:** This describes a **pseudomembrane** (seen in conditions like Adenoviral EKC or Vernal Keratoconjunctivitis). Pseudomembranes consist of coagulated exudate deposited *on* the epithelium and can be peeled easily without bleeding. * **Option C:** *Corynebacterium diphtheriae* is the classic causative agent of **true membranous conjunctivitis**, not a false (pseudo) membrane. In an unvaccinated child, Diphtheria must be the primary clinical suspicion. * **Option D:** The membrane *can* be removed manually, but it is discouraged in the acute phase due to the risk of significant bleeding and subsequent scarring (symblepharon). **3. High-Yield Clinical Pearls for NEET-PG:** * **Common Causes:** *C. diphtheriae* (most common in unvaccinated), virulent *Streptococcus pyogenes*. * **Clinical Stages:** 1. Stage of Infiltration (brawny edema), 2. Stage of Suppuration (membrane sloughing), 3. Stage of Cicatrization (scarring). * **Complications:** Symblepharon (adhesion of lids to eyeball), Trichiasis, and **Corneal Ulceration** (due to toxic enzymes or secondary infection). * **Treatment:** Immediate topical and systemic Penicillin/Erythromycin; Anti-diphtheritic serum (ADS) is critical if Diphtheria is suspected.

Question 57: Tear lysozyme levels are decreased in which of the following conditions?

A. Keratoconjunctivitis sicca (Correct Answer)
B. Stevens Johnson syndrome
C. Ocular pemphigoid
D. All of the above

Explanation: **Explanation:** **1. Understanding the Concept:** Lysozyme is a major antibacterial enzyme secreted by the **main and accessory lacrimal glands**. It accounts for about 20-40% of total tear protein. In conditions where there is primary lacrimal gland dysfunction or atrophy, the concentration of lysozyme in the tear film drops significantly. **Keratoconjunctivitis Sicca (KCS)**, specifically the aqueous-deficient subtype (often seen in Sjögren’s syndrome), is characterized by the hypofunction of the lacrimal glands. Therefore, a **decrease in tear lysozyme levels** is a classic biochemical marker for KCS and is used as a diagnostic indicator of lacrimal secretory capacity. **2. Analysis of Options:** * **A. Keratoconjunctivitis sicca (Correct):** As explained, the primary pathology involves reduced aqueous production from the lacrimal glands, leading to a direct fall in lysozyme levels. * **B & C. Stevens-Johnson Syndrome (SJS) and Ocular Pemphigoid (Incorrect):** While these conditions cause severe "dry eye," the primary mechanism is **mucin deficiency** due to the destruction of conjunctival goblet cells and scarring of the lacrimal gland ducts (obstructive) rather than a primary failure of lysozyme production itself. While lysozyme may eventually decrease in late stages, KCS is the classic textbook association for this specific biochemical change. **3. NEET-PG High-Yield Pearls:** * **Schirmer’s Test:** Used to measure aqueous tear production. <5mm in 5 minutes is diagnostic for dry eye. * **Tear Film Break-up Time (BUT):** Measures mucin deficiency/tear stability. Normal is 15–35 seconds; <10 seconds is abnormal. * **Rose Bengal Stain:** Stains dead and devitalized epithelial cells (useful in KCS). * **Lactoferrin:** Another antibacterial protein that, like lysozyme, is decreased in aqueous-deficient dry eye.

Question 58: Phlycten is due to which of the following?

A. Exogenous allergy
B. Endogenous allergy (Correct Answer)
C. Viral keratitis
D. Fungal keratitis

Explanation: **Explanation:** **Phlyctenular Keratoconjunctivitis** is a localized delayed hypersensitivity reaction (Type IV) to an **endogenous microbial antigen** to which the ocular tissues have become sensitized. 1. **Why "Endogenous Allergy" is correct:** The term "endogenous" refers to the fact that the allergen is already present within the body (usually from a distant focus of infection). The phlycten is not an infection itself, but an allergic response to bacterial proteins. Historically, the most common cause was **Tuberculosis** (Mycobacterium tuberculosis). In modern clinical practice, the most common cause is **Staphylococcal protein** (associated with chronic blepharitis). 2. **Why other options are incorrect:** * **Exogenous allergy:** This refers to external allergens like pollen or dust (e.g., Vernal Keratoconjunctivitis). Phlycten is triggered by internal bacterial proteins, not external environmental factors. * **Viral/Fungal keratitis:** These are direct infectious processes where the pathogen invades the corneal tissue. Phlycten is an immunological (allergic) reaction, and the nodule itself is sterile. **High-Yield Clinical Pearls for NEET-PG:** * **Characteristic Lesion:** A small, pinkish-white nodule near the limbus, surrounded by localized hyperemia. * **Pathology:** The phlycten is a subepithelial infiltration of lymphocytes and macrophages. * **Symptoms:** Intense itching, lacrimation, and photophobia (especially if it involves the cornea). * **Fascicular Ulcer:** A specific type of ulcer formed when a limbal phlycten migrates towards the center of the cornea, carrying a leash of blood vessels behind it. * **Treatment:** Topical steroids (to control the allergy) and treatment of the underlying cause (e.g., lid hygiene for Staph or systemic workup for TB).

Question 59: Topical sodium cromoglycate is used in the treatment of which condition?

A. Phlyctenular conjunctivitis
B. Vernal catarrh (Correct Answer)
C. Subconjunctival haemorrhage
D. Trachoma

Explanation: ### Explanation **Correct Answer: B. Vernal catarrh** **Why it is correct:** Vernal Keratoconjunctivitis (VKC), or Vernal catarrh, is a bilateral, recurrent, seasonal allergic inflammation of the conjunctiva. It is primarily a **Type I hypersensitivity reaction** mediated by IgE and mast cell degranulation. **Sodium cromoglycate** is a **mast cell stabilizer**; it works by preventing the release of inflammatory mediators (like histamine) from mast cells. It is used as a prophylactic agent to reduce the frequency and severity of acute attacks in VKC. **Why the other options are incorrect:** * **Phlyctenular conjunctivitis:** This is a **Type IV hypersensitivity reaction** (delayed) to endogenous bacterial proteins (most commonly Tubercular or Staphylococcal). Treatment focuses on topical steroids and treating the underlying cause, not mast cell stabilization. * **Subconjunctival haemorrhage:** This is usually a self-limiting condition caused by the rupture of a small conjunctival vessel. It requires no specific treatment other than reassurance, as the blood resorbs within 1–2 weeks. * **Trachoma:** This is a chronic infectious keratoconjunctivitis caused by *Chlamydia trachomatis*. The mainstay of treatment is the **SAFE strategy**, specifically antibiotics like Azithromycin or Tetracycline. **High-Yield Clinical Pearls for NEET-PG:** * **VKC Hallmarks:** Characterized by "cobblestone" papillae on the superior tarsal conjunctiva, **Horner-Tranta’s dots** (limbal white dots), and **Shield ulcers** (sterile indolent ulcers). * **Drug of Choice for Acute Attack:** Topical steroids are used for rapid relief of symptoms, while mast cell stabilizers (Cromoglycate) or dual-action agents (Olopatadine) are used for long-term maintenance. * **Cytology:** Conjunctival scrapings in VKC characteristically show an abundance of **eosinophils**.

Question 60: What is the incubation period of gonococcal ophthalmia neonatorum?

A. 24 hours
B. 5-7 days
C. 7-10 days
D. None of the above (Correct Answer)

Explanation: **Explanation:** The correct answer is **None of the above** because the incubation period for **Gonococcal Ophthalmia Neonatorum** is typically **2 to 5 days**. **1. Why "None of the above" is correct:** Gonococcal conjunctivitis, caused by *Neisseria gonorrhoeae*, is a hyperacute purulent conjunctivitis. It typically manifests within the first week of life, specifically between **days 2 and 5** after birth. Since none of the provided options (24 hours, 5-7 days, or 7-10 days) accurately capture this specific window, "None of the above" is the most accurate choice. **2. Analysis of Incorrect Options:** * **A. 24 hours:** This is too early for a bacterial infection. Chemical conjunctivitis (often due to silver nitrate prophylaxis) typically appears within the first 24 hours. * **B. 5-7 days:** While there is slight overlap, this timeframe is more characteristic of other bacterial infections like *Staphylococcus aureus* or *Streptococcus pneumoniae*. * **C. 7-10 days:** This delayed onset is the classic incubation period for **Chlamydial conjunctivitis** (Inclusion blennorrhea), which is the most common cause of ophthalmia neonatorum worldwide. **3. NEET-PG High-Yield Clinical Pearls:** * **Most Common Cause:** Chlamydia trachomatis (Onset: 5–14 days). * **Most Destructive/Serious Cause:** Neisseria gonorrhoeae (can cause intact corneal perforation). * **Treatment of Choice (Gonococcal):** Systemic Ceftriaxone (25–50 mg/kg IV/IM, single dose). * **Prophylaxis:** Povidone-iodine (5%) or Erythromycin ointment is used immediately after birth to prevent infection. * **Key Sign:** Gonococcal infection is characterized by "chemosis" and "profuse purulent discharge" (often described as "pus pouring out" when eyelids are opened).

Practice by Chapter

Conjunctivitis: Bacterial

Practice Questions

Conjunctivitis: Viral

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Conjunctivitis: Allergic

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Conjunctivitis: Chronic

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Degenerations of Conjunctiva

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Benign Tumors of Conjunctiva

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Malignant Tumors of Conjunctiva

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Conjunctival Manifestations of Systemic Diseases

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Cicatricial Conjunctival Disorders

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Pterygium and Pinguecula

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Conjunctival Trauma

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Subconjunctival Hemorrhage

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