Diseases of the Cornea Practice Questions

Q: A patient wakes up at 3 AM with acute pain. On examination 7 hours later, the eye appears quiet, with mild corneal stippling and irregularity. What is the most probable diagnosis?

Recurrent corneal erosion. **Explanation:** **Recurrent Corneal Erosion (RCE)** syndrome is the most probable diagnosis based on the classic clinical presentation. 1. **Why it is correct:** RCE typically occurs due to a weak basement membrane attachment (often following previous trauma or associated with Map-Dot-Fingerprint dystrophy). The hallmark is **sudden, sharp pain upon awakening** (often around 3 AM or early morning). This happens because the eyelid adheres to the loose corneal epithelium overnight; when the patient opens their eyes or during REM sleep, the epithelium is "ripped" off. By the time the patient is examined hours later, the epithelium may have partially healed or repositioned, leaving only **mild stippling or irregularity** on a relatively "quiet" (non-inflamed) eye. 2. **Why incorrect options are wrong:** * **Contact lens overwear:** Usually presents with significant conjunctival injection (red eye) and diffuse punctate keratitis; the pain is typically gradual and occurs while wearing the lenses, not specifically at 3 AM. * **Corneal ulcer:** This is an acute infection. The eye would be severely congested (ciliary flush), with a visible infiltrate and persistent, worsening pain. * **Angle closure glaucoma:** While it causes acute pain, it is associated with a hazy cornea, mid-dilated fixed pupil, and systemic symptoms like nausea/vomiting. The eye would not appear "quiet." **Clinical Pearls for NEET-PG:** * **Management:** Acute phase involves lubricant ointments and patching/bandage contact lenses. Long-term prevention includes hypertonic saline (5% NaCl) drops at bedtime to dehydrate the epithelium and improve adhesion. * **Surgical options:** For recalcitrant cases, **Anterior Stromal Puncture** or **PTK (Phototherapeutic Keratectomy)** are high-yield treatments. * **Key Trigger:** Sudden eye opening in the morning.

Q: What are the indications for using Collagen cross-linking?

Fungal corneal ulcer. **Explanation:** **Collagen Cross-linking (CXL)**, traditionally used for Keratoconus, has evolved into **PACK-CXL (Photoactivated Chromophore for Infectious Keratitis)**. 1. **Why B is correct:** In **Fungal Corneal Ulcers** (and some bacterial ulcers), PACK-CXL serves as an adjuvant therapy. The combination of Riboflavin (Vitamin B2) and UV-A light creates a photochemical reaction that produces reactive oxygen species. This process has a dual benefit: it directly kills pathogens (fungi/bacteria) and strengthens the corneal stroma by creating covalent bonds between collagen fibrils, making the cornea more resistant to enzymatic degradation (melting) by microbial proteases. 2. **Why other options are incorrect:** * **A. Herpes infection:** CXL is generally **contraindicated** in active viral keratitis (HSV) as UV light can trigger viral reactivation and worsen the condition. * **C. Pachymetry less than 400 µm:** This is a **contraindication**. The standard Dresden protocol requires a minimum corneal thickness of 400 µm (after debridement) to protect the corneal endothelium from UV-induced damage. (Note: The option says 'nm', which is a unit error, but the value 400 refers to the safety threshold in µm). * **D. Severe dry eye:** This is not an indication. In fact, CXL can temporarily worsen dry eye symptoms due to corneal nerve damage during the procedure. **High-Yield Pearls for NEET-PG:** * **Standard Protocol:** Dresden Protocol (3 mW/cm² for 30 mins). * **Chromophore used:** Riboflavin (Vitamin B2). * **Light source:** UV-A (365 nm). * **Primary Indication:** Progressive Keratoconus (to halt progression, not to improve vision). * **PACK-CXL:** Specifically refers to its use in infectious keratitis.

Q: All are causes of a non-healing corneal ulcer except?

Associated iridocyclitis. **Explanation:** A non-healing (indolent) corneal ulcer is one that fails to show signs of healing despite appropriate antimicrobial therapy. The management of such cases requires identifying and treating the underlying systemic or local factors that impede epithelialization. **Why "Associated Iridocyclitis" is the correct answer:** Iridocyclitis (anterior uveitis) is a **common clinical feature** of almost all significant corneal ulcers due to the diffusion of toxins into the anterior chamber. It is a *consequence* of the ulcer, not a cause of delayed healing. In fact, treating the associated iridocyclitis with cycloplegics (like Atropine) is a standard part of the management to reduce pain and prevent synechiae. **Analysis of Incorrect Options (Causes of Non-healing Ulcers):** * **Raised Intraocular Pressure (A):** Increased IOP causes mechanical stress on the corneal endothelium and stroma, leading to corneal edema. This interferes with the migration and adhesion of the epithelial basement membrane, preventing the ulcer from healing. * **Chronic Dacryocystitis (C):** This is a classic "high-yield" cause. The lacrimal sac acts as a reservoir for bacteria (commonly *S. pneumoniae*), leading to a constant "rain of infection" onto the cornea, causing recurrence or non-healing. * **Diabetes Mellitus (D):** Systemic conditions like DM impair healing through peripheral neuropathy (decreased corneal sensation/neurotrophic effect) and impaired microcirculation and immune response. **Clinical Pearls for NEET-PG:** * **Most common cause of a non-healing ulcer:** Local factors like Chronic Dacryocystitis or Lagophthalmos. * **Rule of thumb:** Always check the patency of the lacrimal passages (Syringing) in any patient with a corneal ulcer. * **Other causes:** Vitamin A deficiency, Neurotrophic keratitis (CN V palsy), and Corticosteroid abuse.

Q: A soft contact lens wearer developed pain and itching of the eye and showed a reticular pattern on the corneal epithelium. What is the likely cause of these symptoms?

Acanthamoeba infection. ### Explanation **Correct Answer: B. Acanthamoeba infection** The clinical presentation of a **soft contact lens wearer** presenting with severe pain and a **reticular (radial) pattern** on the cornea is a classic description of **Acanthamoeba keratitis**. The "reticular pattern" refers to **radial keratoneuritis**, which is the infiltration of the corneal nerves by the *Acanthamoeba* trophozoites. This involvement of the nerves explains why the pain is often **disproportionate** to the clinical signs (severe pain despite minimal initial findings). Contact lens wear, especially with poor hygiene or use of tap water, is the most significant risk factor. **Why other options are incorrect:** * **Corneal dystrophy (A):** These are typically bilateral, symmetrical, and slowly progressive genetic conditions. They do not present with acute pain or itching associated with contact lens use. * **Pseudomonas infection (C):** While common in contact lens wearers, *Pseudomonas* causes a rapidly progressing suppurative ulcer with a characteristic **greenish-yellow discharge** and a large hypopyon, rather than a radial nerve pattern. * **Viral keratitis (D):** Herpes Simplex Keratitis typically presents with a **dendritic ulcer** (linear branching with terminal bulbs) and decreased corneal sensations, rather than the intense pain of radial keratoneuritis. **High-Yield Clinical Pearls for NEET-PG:** * **Pathognomonic Sign:** Radial keratoneuritis (radial perineural infiltrates). * **Late Sign:** Ring-shaped stromal infiltrate. * **Diagnosis:** Culture on **Non-nutrient agar with E. coli overlay**. * **Stains:** Calcofluor white (fluorescent) or Periodic acid-Schiff (PAS). * **Treatment:** Topical biguanides (PHMB 0.02%) or Diamidines (Propamidine/Brolene).

Q: Fascicular ulcer is seen in which of the following conditions?

Phlyctenular keratitis. ### Explanation **Phlyctenular keratitis** is the correct answer because a **fascicular ulcer** is its most characteristic clinical manifestation. #### 1. Why Phlyctenular Keratitis is Correct Phlyctenular keratoconjunctivitis is a delayed hypersensitivity reaction (Type IV) to endogenous bacterial proteins, most commonly **Tuberculosis** (in developing countries) or **Staphylococcus** (in developed countries). * **Mechanism of Fascicular Ulcer:** A phlycten (a small greyish nodule) starts at the limbus and migrates towards the center of the cornea. As it moves, it carries a "leash" of superficial blood vessels behind it. The leading edge remains an active ulcer while the trailing edge heals, resulting in a **serpiginous, wandering ulcer** with a characteristic vascular leash. It typically does not perforate but leaves a permanent superficial opacity (nebula). #### 2. Why Other Options are Incorrect * **Rosacea Keratitis:** Characteristically presents with peripheral corneal vascularization, marginal infiltrates, and spade-shaped scarring. It is associated with acne rosacea of the face. * **Riboflavin (Vitamin B2) Deficiency:** Classically associated with **circumcorneal vascularization** (neovascularization) and angular stomatitis, but it does not produce a migrating fascicular ulcer. #### 3. High-Yield Clinical Pearls for NEET-PG * **Etiology:** Always look for "History of TB" or "Positive Mantoux test" in the clinical vignette. * **Symptoms:** Intense photophobia is a hallmark when the cornea is involved. * **Treatment:** Topical steroids are the mainstay to control the hypersensitivity reaction, along with treating the underlying cause (e.g., ATT for TB or lid hygiene for Staph). * **Differential Diagnosis:** Do not confuse the vascular leash of a fascicular ulcer with a **Pannus** (seen in Trachoma), which is inflammatory vascularization usually limited to the upper quadrant.

Q: A 55-year-old cardiac patient on long-term treatment presents for a follow-up visit. The physician observes the following finding on ophthalmological examination. Which drug prescribed by the physician would most probably be responsible for this?

Amiodarone. ***Amiodarone*** - **Amiodarone** commonly causes **corneal microdeposits** (vortex keratopathy/cornea verticillata) in up to 90% of patients on long-term therapy, appearing as whorl-like deposits in the corneal epithelium. - These deposits are **reversible** upon discontinuation and rarely affect vision, making them a characteristic but benign finding in amiodarone users. *Digoxin* - **Digoxin toxicity** primarily causes **visual disturbances** like yellow-green halos and blurred vision, not corneal deposits. - Ocular effects are related to **retinal toxicity** and altered color perception rather than structural corneal changes. *Verapamil* - **Verapamil** is a calcium channel blocker that does not typically cause **corneal deposits** or significant ophthalmological findings. - Side effects are primarily cardiovascular (bradycardia, hypotension) and do not include characteristic ocular manifestations. *Propranolol* - **Propranolol** may cause **dry eyes** and reduced tear production but does not cause corneal microdeposits. - Beta-blockers can worsen **glaucoma** in susceptible patients but do not produce the whorl-like corneal pattern seen with amiodarone.

Q: What are the characteristic features of a fungal corneal ulcer?

Dry ulcer. **Explanation:** Fungal corneal ulcers (keratomycosis) typically present with distinct clinical features that differentiate them from bacterial ulcers. The correct answer is **Dry ulcer** because fungal lesions are characterized by a firm, elevated, and leathery texture. Unlike the "wet" or melting appearance of bacterial ulcers, fungal hyphae infiltrate the stroma without producing the same level of liquefactive necrosis, leading to a **dry, grayish-white appearance**. **Analysis of Options:** * **A. Symptoms disproportionate to signs:** This is a classic feature of **Acanthamoeba keratitis**, where the patient experiences excruciating pain despite minimal clinical findings. In fungal ulcers, the opposite is often true: signs are often more prominent than symptoms (the patient may feel relatively comfortable despite a large ulcer). * **C. Diffuse corneal edema:** While some edema may occur, it is not a "characteristic" diagnostic feature. Fungal ulcers are more specifically known for **Feathered margins**, **Satellite lesions**, and an **Immune ring (Wessely ring)**. * **D. All of the above:** Incorrect, as options A and C are not primary characteristics of fungal keratitis. **NEET-PG High-Yield Pearls:** * **Etiology:** Most common cause in India is *Aspergillus* (filamentous); *Candida* is more common in pre-existing ocular surface disease. * **Risk Factor:** Trauma with **vegetative matter** (e.g., a branch or leaf). * **Clinical Signs:** Look for "Fixed Hypopyon" (thick, non-mobile) and "Endothelial plaques." * **Diagnosis:** **KOH mount** (10-20%) is the fastest bedside test; **Sabouraud’s Dextrose Agar (SDA)** is the gold standard culture medium. * **Treatment:** Topical **Natamycin (5%)** is the drug of choice for filamentous fungi. Avoid topical steroids as they worsen the infection.

Q: What is the characteristic color of fluorescein staining in a corneal ulcer?

Green. **Explanation:** **Mechanism of Staining:** Sodium Fluorescein is a vital dye used to assess corneal integrity. It is **water-soluble** and cannot penetrate the intact, lipid-rich corneal epithelium. In a corneal ulcer, the epithelium is breached, exposing the underlying **corneal stroma**. The dye dissolves into the stromal fluid, and when viewed under a **cobalt blue light**, it fluoresces a brilliant **apple-green** color. **Analysis of Options:** * **D. Green (Correct):** This is the characteristic color of fluorescence. The dye absorbs blue light (wavelength ~490 nm) and emits a longer wavelength in the green spectrum (~525 nm). * **A. Yellow:** While the fluorescein strip or concentrated drops appear orange-yellow to the naked eye, the diagnostic "staining" refers to the fluorescence seen under blue light, which is green. * **B. & C. Blue/Royal Blue:** These represent the color of the **filter** (Cobalt blue) used on the slit lamp to excite the dye, not the color of the stain itself. **Clinical Pearls for NEET-PG:** * **Seidel’s Test:** Used to detect aqueous leakage (e.g., globe perforation). A positive test shows a "streaming" of clear aqueous fluid through the green fluorescein. * **Dendritic Ulcers:** Fluorescein stains the **bed** of the ulcer (where cells are missing), while Rose Bengal or Lissamine Green stains the **devitalized cells** at the margins. * **Contact Lenses:** Fluorescein should be avoided with soft contact lenses as it permanently stains them. * **Jones Test:** Uses fluorescein to check the patency of the nasolacrimal duct.

Q: Which of the following are features of a fungal corneal ulcer?

Hyphenated margins. **Explanation:** Fungal corneal ulcers (keratomycosis), most commonly caused by *Aspergillus*, *Fusarium*, or *Candida*, present with distinct clinical features due to the slow-growing nature of fungi and the host's inflammatory response. **Why "Hyphenated margins" is correct:** Fungal hyphae tend to infiltrate the corneal stroma by spreading horizontally and vertically. This creates irregular, feathery, or **hyphenated margins** around the main ulcer. Other characteristic features include a **dry, leathery appearance**, **satellite lesions** (small infiltrates away from the main ulcer), and a **fixed hypopyon** (which is often sterile but thick and non-mobile). **Analysis of Incorrect Options:** * **A. Symptoms more than signs:** This is a hallmark of **Acanthamoeba keratitis**, where the pain is excruciating and out of proportion to the clinical findings. In fungal ulcers, signs are often more prominent than symptoms (the patient may feel relatively comfortable despite a large ulcer). * **B. Dry ulcer:** While fungal ulcers are indeed "dry" and "leathery," this option is less specific than "hyphenated margins" in the context of classic board-style questions. However, in some contexts, this is a feature; but hyphenated margins are the pathognomonic clinical sign. * **C. Diffuse corneal edema:** This is more characteristic of **Bacterial ulcers** or acute glaucoma. Fungal ulcers typically have localized edema around the infiltrate rather than diffuse edema. **High-Yield Clinical Pearls for NEET-PG:** * **History:** Often follows trauma with **vegetative matter** (e.g., a branch or leaf). * **Immune Ring:** A Wessely immune ring may be seen (host response to fungal antigens). * **Diagnosis:** Gold standard is **Sabouraud’s Dextrose Agar (SDA)**; KOH mount shows hyphae. * **Treatment:** Topical **Natamycin** (5%) is the drug of choice for filamentous fungi; Amphotericin B for *Candida*. Avoid steroids.

Q: Which of the following stains is used in granular dystrophy of the cornea?

Masson's trichrome. **Explanation:** Corneal dystrophies are a high-yield topic for NEET-PG, often tested through the association of specific deposits with their respective histological stains. **1. Why Masson’s Trichrome is Correct:** **Granular Dystrophy** is characterized by the deposition of **hyaline material** in the superficial stroma. On histopathology, these deposits appear as bright red granules when stained with **Masson’s Trichrome**. This is the gold-standard stain for identifying hyaline in corneal tissue. **2. Analysis of Incorrect Options:** * **A. Congo-red:** This is the specific stain for **Lattice Dystrophy**, which involves the deposition of **amyloid**. Under polarized light, Congo-red stained amyloid shows a characteristic "apple-green birefringence." * **C. Colloidal Iron:** This (along with Alcian Blue) is used to stain **Macular Dystrophy**, which involves the deposition of **Acid Mucopolysaccharides (Glycosaminoglycans)**. * **D. PAS (Periodic Acid-Schiff):** While PAS stains basement membranes and certain carbohydrates, it is not the primary diagnostic stain for Granular Dystrophy. It is more commonly associated with fungal filaments or Descemet’s membrane pathology. **3. High-Yield Clinical Pearls (Mnemonic: "Marilyn Monroe Got Hers"):** To remember the associations for NEET-PG, use this classic mnemonic: * **M**acular – **M**ucopolysaccharide – **A**lcian Blue/Colloidal Iron (**M.A.**) * **G**ranular – **H**yaline – **M**asson’s Trichrome (**G.H.M.**) * **L**attice – **A**myloid – **C**ongo Red (**L.A.C.**) **Additional Fact:** Granular Dystrophy is an **Autosomal Dominant** condition (TGFBI gene mutation) and typically presents with "crumb-like" opacities with clear spaces in between.

Question 1

A patient wakes up at 3 AM with acute pain. On examination 7 hours later, the eye appears quiet, with mild corneal stippling and irregularity. What is the most probable diagnosis?

Accepted Answer

Recurrent corneal erosion

Answer

Contact lens overwear syndrome

Answer

Corneal ulcer

Answer

Angle closure glaucoma

Question 2

What are the indications for using Collagen cross-linking?

Accepted Answer

Fungal corneal ulcer

Answer

Herpes infection

Answer

Pachymetry less than 400 nm

Answer

Severe dry eye

Question 3

All are causes of a non-healing corneal ulcer except?

Accepted Answer

Associated iridocyclitis

Answer

Raised intraocular pressure

Answer

Chronic dacryocystitis

Answer

Diabetes mellitus

Question 4

A soft contact lens wearer developed pain and itching of the eye and showed a reticular pattern on the corneal epithelium. What is the likely cause of these symptoms?

Accepted Answer

Acanthamoeba infection

Answer

Corneal dystrophy

Answer

Pseudomonas infection

Answer

Viral keratitis

Question 5

Fascicular ulcer is seen in which of the following conditions?

Accepted Answer

Phlyctenular keratitis

Answer

Rosacea keratitis

Answer

Riboflavin deficiency

Answer

All of the above

Question 6

A 55-year-old cardiac patient on long-term treatment presents for a follow-up visit. The physician observes the following finding on ophthalmological examination. Which drug prescribed by the physician would most probably be responsible for this?

Accepted Answer

Amiodarone

Answer

Digoxin

Answer

Verapamil

Answer

Propranolol

Question 7

What are the characteristic features of a fungal corneal ulcer?

Accepted Answer

Dry ulcer

Answer

Symptoms disproportionate to signs

Answer

Diffuse corneal edema

Answer

All of the above

Question 8

What is the characteristic color of fluorescein staining in a corneal ulcer?

Accepted Answer

Green

Answer

Yellow

Answer

Blue

Answer

Royal blue

Question 9

Which of the following are features of a fungal corneal ulcer?

Accepted Answer

Hyphenated margins

Answer

Symptoms more than signs

Answer

Dry ulcer

Answer

Diffuse corneal edema

Question 10

Which of the following stains is used in granular dystrophy of the cornea?

Accepted Answer

Masson's trichrome

Answer

Congo-red

Answer

Colloidal iron

Answer

PAS

Diseases of the Cornea — MCQs

Diseases of the Cornea — MCQs

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