Diseases of the Cornea Practice Questions

Q: A 25-year-old man presented with a history of pain, redness, and watering of the left eye for the last 1 day. There is also photophobia. What is the most probable diagnosis?

Keratitis. **Explanation:** The clinical presentation of acute onset pain, redness, watering, and photophobia in a young male is characteristic of an inflammatory or infectious process of the cornea or anterior segment. **Why Keratitis is the Correct Answer:** Keratitis (corneal inflammation) typically presents with the classic triad of **pain, photophobia, and lacrimation (watering)**. The pain in keratitis is often described as a "foreign body sensation" due to the rich nerve supply of the corneal epithelium. The presence of significant watering (reflex lacrimation) and photophobia strongly points toward corneal involvement. **Analysis of Incorrect Options:** * **Acute Anterior Uveitis:** While it presents with pain, redness, and photophobia, the hallmark is a "dull, aching pain" and a **constricted, sluggish pupil** (miosis). Watering is usually less prominent than in keratitis. * **Acute Posterior Uveitis:** This condition is typically **painless** and presents primarily with floaters or blurred vision. It does not cause redness or watering of the external eye. * **Epidemic Keratoconjunctivitis (EKC):** Caused by Adenovirus, it presents with significant **mucoid/watery discharge** and follicles. While it can cause keratitis (subepithelial opacities), the question describes a more localized acute presentation where keratitis is the primary pathological diagnosis for the symptoms provided. **NEET-PG Clinical Pearls:** * **Ciliary Congestion:** A key sign in both Keratitis and Anterior Uveitis (circumcorneal flush), distinguishing them from Conjunctivitis (conjunctival congestion). * **Fluorescein Staining:** The gold standard bedside test to confirm Keratitis (epithelial defect). * **Photophobia Mechanism:** In keratitis, photophobia occurs due to trigeminal nerve irritation and reflex ciliary muscle spasm.

Q: In Herpes zoster keratitis, which of the following clinical presentations is LEAST likely to occur?

Sclerokeratitis. **Explanation:** In **Herpes Zoster Ophthalmicus (HZO)**, the virus (Varicella-Zoster) affects the ophthalmic division of the trigeminal nerve. While it can involve almost every layer of the eye, the question asks for the **least likely** presentation among the options provided. **1. Why Sclerokeratitis is the correct answer:** While HZO can cause scleritis and keratitis independently, **Sclerokeratitis** (inflammation of the sclera that spreads to involve the adjacent cornea) is a relatively rare complication compared to the direct corneal and uveal manifestations. In the context of NEET-PG, HZO is classically associated with epithelial, stromal, and endothelial involvement rather than primary scleral-driven corneal disease. **2. Analysis of other options:** * **Pseudodendritic Keratitis (A):** This is a hallmark of HZO. Unlike the true dendrites of Herpes Simplex (HSV), these are elevated, stuck-on lesions without terminal bulbs and do not stain well with fluorescein. * **Anterior Uveitis with Endothelial Keratitis (B):** HZO frequently causes a hypertensive anterior uveitis (due to vasculitis) often accompanied by inflammation of the corneal endothelium. * **Endothelitis (D):** This is a common manifestation where the virus triggers an immune response at the endothelial level, leading to localized corneal edema and Keratic Precipitates (KPs). **Clinical Pearls for NEET-PG:** * **Hutchinson’s Sign:** Vesicles on the tip of the nose (involvement of the nasociliary nerve) strongly predict ocular involvement. * **HSV vs. HZO Dendrite:** HSV has **true dendrites** (central ulceration, terminal bulbs); HZO has **pseudodendrites** (tapered ends, no terminal bulbs). * **Treatment:** Oral Acyclovir (800 mg 5 times daily) is the mainstay for HZO, which is double the dose used for HSV. * **Neurotrophic Keratopathy:** A common late complication due to loss of corneal sensations.

Q: Important in Herpes simplex involvement of the eye are all EXCEPT:

Purulent discharge. **Explanation:** Herpes Simplex Virus (HSV) keratitis is a leading cause of corneal blindness. The correct answer is **Purulent discharge**, as this is a hallmark of **bacterial conjunctivitis/keratitis**, not viral infections. Viral infections typically present with watery (serous) discharge. **Why the other options are characteristic of HSV:** * **Type of lesion (Option A):** HSV is famous for its specific morphological patterns. The most common is the **dendritic ulcer** (linear, branching with terminal bulbs), which stains with Fluorescein. If treated with steroids, it can enlarge into a **geographic ulcer**. * **Corneal anaesthesia (Option B):** HSV is a neurotropic virus that resides in the trigeminal ganglion. Its replication leads to the destruction of corneal nerve endings, resulting in **marked corneal hypoesthesia or anesthesia**. This is a classic diagnostic sign. * **Iridocyclitis (Option C):** HSV can cause secondary anterior uveitis (iridocyclitis) either through direct viral invasion or an immunologic reaction. It is often associated with high intraocular pressure (hypertensive uveitis). **High-Yield Clinical Pearls for NEET-PG:** * **Staining:** The floor of the dendritic ulcer stains with **Fluorescein**, while the virus-laden cells at the margins (terminal bulbs) stain with **Rose Bengal**. * **Treatment:** Topical **Acyclovir (3%)** or Ganciclovir gel is the gold standard. **Steroids are strictly contraindicated** in epithelial (dendritic) keratitis as they promote viral replication, leading to geographic ulcers. * **Recurrence:** HSV remains latent in the **Trigeminal (V) ganglion**. * **Disciform Keratitis:** This is a type of stromal involvement characterized by a central, disc-shaped area of corneal edema, thought to be a Type IV hypersensitivity reaction.

Q: A 20-year-old male presents with sudden onset left eye pain and vision loss. Examination reveals a hazy left cornea. Upon looking down, a bulge is noted in the lower eyelid. Retinoscopy demonstrates a scissoring reflex and a positive oil drop sign in both eyes. What is the diagnosis?

Keratoconus. **Explanation:** The clinical presentation is a classic case of **Keratoconus**, a non-inflammatory, progressive thinning and ectasia of the central or paracentral cornea. **Why Keratoconus is correct:** * **Munson’s Sign:** The "bulge in the lower eyelid upon looking down" is a pathognomonic sign caused by the cone-shaped cornea indenting the lid. * **Oil Drop Sign:** Seen on distant direct ophthalmoscopy, this represents the conical protrusion. * **Scissoring Reflex:** Observed during retinoscopy due to irregular astigmatism. * **Acute Hydrops:** The "sudden onset pain and vision loss with a hazy cornea" indicates a rupture in **Descemet’s membrane**, leading to stromal edema (Acute Hydrops), a known complication of keratoconus. **Why other options are incorrect:** * **Corneal Dystrophy:** These are typically bilateral, symmetrical, and slowly progressive without the specific conical bulging or Munson’s sign. * **Pathological Myopia:** While it causes vision loss and high refractive error, it involves posterior segment changes (e.g., Fuchs' spot, staphyloma) rather than corneal ectasia or Munson's sign. * **Keratoglobus:** This involves hemispherical protrusion and thinning of the *entire* cornea from limbus to limbus, rather than a localized cone. It rarely presents with acute hydrops. **High-Yield Clinical Pearls for NEET-PG:** * **Fleischer’s Ring:** Iron deposition at the base of the cone (best seen with Cobalt blue filter). * **Vogt’s Striae:** Vertical stress lines in the deep stroma. * **Rizutti’s Sign:** Conical reflection on the nasal cornea when light is shone from the temporal side. * **Management:** Early stages use spectacles/RGP lenses; **Collagen Cross-linking (CXL/C3R)** stops progression; Keratoplasty is for advanced cases. *Note: Steroids are contraindicated in acute hydrops.*

Q: Posterior polymorphous dystrophy is characterized by which of the following?

Corectopia. **Explanation:** **Posterior Polymorphous Dystrophy (PPMD)** is a rare, usually autosomal dominant, bilateral corneal dystrophy affecting the corneal endothelium and Descemet membrane. **Why Corectopia is Correct:** The hallmark of PPMD is the transformation of corneal endothelial cells into "epithelial-like" cells. These abnormal cells have a migratory property; they can grow across the trabecular meshwork and onto the surface of the iris. As these membranes contract, they pull the iris, leading to **corectopia** (displacement of the pupil), ectropion uveae, and peripheral anterior synechiae (PAS). This mechanism is similar to that seen in Iridocorneal Endothelial (ICE) syndrome. **Analysis of Incorrect Options:** * **B. Autosomal recessive inheritance:** PPMD is typically inherited in an **Autosomal Dominant** pattern (linked to mutations in *ZEB1*, *COL8A2*, or *OVOL2* genes). * **C. Blindness in over 90% of sufferers:** Most patients are asymptomatic and the condition is often stable. Only a small percentage develop significant corneal edema or secondary glaucoma leading to severe vision loss. * **D. Treatment with lamellar corneal grafts:** While severe cases require surgery, the standard is **Penetrating Keratoplasty (PK)** or **Endothelial Keratoplasty (DSEK/DMEK)**. Simple lamellar grafts (which replace only the stroma) do not address the underlying endothelial pathology. **High-Yield Clinical Pearls for NEET-PG:** * **Vesicular lesions:** Characterized by "railroad track" or "snail track" opacities on the posterior cornea. * **Glaucoma:** Occurs in ~15% of cases due to membrane overgrowth in the angle. * **Differential Diagnosis:** Must be distinguished from **ICE Syndrome** (which is unilateral and non-hereditary) and **CHED** (Congenital Hereditary Endothelial Dystrophy).

Q: Which of the following is NOT an indication for the prosthesis shown in the image?

Oral Contraceptive Pills (OCP) - Stage 1 or 2. ***Oral Contraceptive Pills (OCP) - Stage 1 or 2*** - **Early-stage OCP** (Stage I-II by Foster/Mondino staging) does NOT qualify for **Boston Keratoprosthesis** as the corneal surface is still manageable with medical therapy. - **Boston KPro** is reserved for **advanced stages (III-IV)** with severe **dry eye**, **surface keratinization**, and failed conventional treatments. *Crouzon Disease* - **Syndromic craniosynostosis** with **shallow orbits** leads to severe **exposure keratopathy** and corneal scarring unresponsive to conventional grafts. - The **anatomical abnormalities** make traditional **penetrating keratoplasty** technically challenging and prone to failure. *Multiple failed Penetrating Keratoplasty* - **Repeated PKP failures** indicate poor **host bed vascularity** or **immune-mediated rejection**, making further conventional grafts futile. - **Boston KPro** bypasses the need for **donor corneal tissue integration** and provides immediate visual rehabilitation. *Epidermolysis Bullosa Acquisita* - **Autoimmune blistering disease** causes severe **cicatricial changes** and **symblepharon formation** that destroy the corneal surface. - The **chronic inflammatory process** makes conventional grafts prone to failure due to poor healing and recurrent scarring.

Q: What is the most common cause of corneal keratitis in soft contact lens users?

Pseudomonas keratitis. **Explanation:** **Pseudomonas keratitis** is the most common cause of bacterial keratitis in soft contact lens wearers. The underlying medical concept involves the ability of *Pseudomonas aeruginosa* to adhere to the surface of soft contact lenses (especially hydrogel and silicone hydrogel types) and the lens cases. It produces proteases and toxins that can cause rapid stromal necrosis and corneal perforation, often presenting as a characteristic "soupy" yellowish-green discharge. **Analysis of Options:** * **Acanthamoeba keratitis:** While highly associated with poor contact lens hygiene (e.g., using tap water), it is much **rarer** than bacterial infections. It is characterized by "pain out of proportion to clinical findings" and ring-shaped infiltrates. * **Corneal erosion:** This is a mechanical complication or a sequela of trauma/dystrophy, not an infectious keratitis. While contact lenses can cause abrasions, they are not the primary "cause" of infectious keratitis itself. * **Herpes simplex keratitis:** This is typically a viral reactivation in the trigeminal ganglion and is not specifically linked to contact lens use. It presents with characteristic dendritic ulcers. **High-Yield Clinical Pearls for NEET-PG:** * **Most common organism overall for bacterial keratitis:** *Staphylococcus aureus*. * **Most common organism in contact lens users:** *Pseudomonas aeruginosa*. * **Risk Factors:** Overnight wear (extended wear) is the single greatest risk factor for developing contact lens-related keratitis. * **Clinical Sign:** Look for a rapidly progressing ulcer with a ground-glass appearance of the surrounding cornea. * **Management:** Immediate cessation of lens wear and intensive topical fortified antibiotics (e.g., Fluoroquinolones or Cephazolin + Gentamicin).

Q: Under hypoxic conditions, which of the following is strongly implicated as a cause of corneal edema?

Lactate. **Explanation:** The cornea maintains its transparency through a state of relative dehydration (deturgescence). This balance is primarily managed by the corneal endothelium's metabolic pump. **Why Lactate is Correct:** Under **hypoxic conditions** (commonly caused by contact lens overwear or epithelial edema), the cornea shifts from aerobic metabolism to **anaerobic glycolysis**. In this pathway, glucose is converted into **lactate** instead of entering the Krebs cycle. Because the corneal epithelium is relatively impermeable to lactate, it accumulates within the corneal stroma. This creates an **osmotic gradient** that draws water from the aqueous humor into the stroma, resulting in **corneal edema**. **Analysis of Incorrect Options:** * **B. Glycogen:** This is the storage form of glucose in the corneal epithelium. During hypoxia, glycogen stores are depleted (not increased) to provide glucose for anaerobic metabolism. * **C. Carbon dioxide:** While CO2 levels may rise slightly during hypoxia, it diffuses rapidly out of the cornea and does not exert the significant osmotic pressure required to cause stromal edema. * **D. Pyruvate:** In the anaerobic pathway, pyruvate is rapidly converted into lactate by the enzyme lactate dehydrogenase (LDH). It is the accumulation of the end-product (lactate), not the intermediate (pyruvate), that drives the osmotic shift. **High-Yield Clinical Pearls for NEET-PG:** * **Maurice’s Theory:** Attributes corneal transparency to the uniform lattice arrangement of collagen fibrils. * **Goldmann’s Theory:** Attributes transparency to the small size of fibrils (less than half the wavelength of light). * **Critical Oxygen Tension:** The minimum oxygen required to prevent corneal edema is approximately **11–19 mmHg**. * **Pachymetry:** The gold standard for measuring corneal thickness; an increase in thickness is the earliest clinical sign of corneal edema.

Q: Which of the following medications is NOT typically administered as eye drops for a corneal ulcer?

Flurometholone. **Explanation:** The management of a corneal ulcer (keratitis) focuses on treating the underlying infection and promoting epithelial healing. **Fluorometholone** is a topical corticosteroid. In the acute phase of a corneal ulcer, steroids are generally **contraindicated** because they inhibit collagen synthesis and suppress the local immune response. This can lead to the worsening of the infection, delayed wound healing, and even corneal perforation (melting). Steroids are only considered in specific bacterial cases once the infection is controlled, to reduce scarring. **Analysis of Options:** * **Chloramphenicol (Option A):** A broad-spectrum bacteriostatic antibiotic frequently used as first-line prophylaxis or treatment for bacterial corneal ulcers. * **Methylcellulose (Option B):** A lubricating agent (artificial tears) used to maintain ocular surface integrity and promote re-epithelialization by reducing friction. * **Olopatadine (Option C):** An antihistamine/mast cell stabilizer. While primarily for allergic conjunctivitis, it is not contraindicated in an ulcer and does not impede healing like steroids do. **Clinical Pearls for NEET-PG:** * **Steroid Contraindication:** Never use steroids in a dendritic ulcer (Herpes Simplex Keratitis) as it leads to a "Geographic ulcer." * **Fortified Antibiotics:** For severe bacterial ulcers, "fortified" drops (e.g., Cefazolin 5% or Tobramycin 1.4%) are preferred over standard strengths. * **Atropine (1%):** Often added to the regimen to relieve ciliary spasm (pain) and prevent posterior synechiae formation. * **Natamycin (5%):** The drug of choice for filamentous fungal corneal ulcers.

Q: KISA% is associated with which of the following conditions?

Keratoconus. **Explanation:** **KISA%** is a quantitative screening index used for the diagnosis and classification of **Keratoconus**. It was developed by Rabinowitz and Rasheed to distinguish normal corneas from those with subclinical or clinical keratoconus using corneal topography data. The index is calculated using four specific parameters: 1. **K:** Central keratometry (K-value). 2. **I-S:** Inferior-Superior dioptric asymmetry. 3. **AST:** Degree of regular astigmatism. 4. **SRAX:** Skewed Radial Axis index. A **KISA% value >100** is considered diagnostic for Keratoconus, while values between 60–100 are suggestive of "suspect" or early disease. **Analysis of Incorrect Options:** * **B. Keratoglobus:** While it is an ectatic dystrophy, it involves generalized thinning and protrusion of the entire cornea (limbus to limbus), unlike the localized paracentral thinning seen in keratoconus where KISA% is specifically applied. * **C. Hypermetropia with astigmatism:** KISA% is a tool for corneal ectasia, not simple refractive errors. * **D. Terrien's marginal degeneration:** This is a peripheral corneal thinning condition characterized by "painless vascularized guttering," usually starting superiorly. It does not utilize the KISA% index for diagnosis. **High-Yield Clinical Pearls for NEET-PG:** * **Munson’s Sign:** V-shaped indentation of the lower lid on down-gaze (late sign). * **Vogt’s Striae:** Vertical stress lines in the deep stroma/Descemet’s membrane. * **Fleischer’s Ring:** Iron deposition at the base of the cone (best seen with cobalt blue filter). * **Rizutti’s Sign:** Conical reflection on the nasal cornea when light is shone from the temporal side. * **Treatment of choice for progression:** Collagen Cross-Linking (CXL/C3R).

Question 1

A 25-year-old man presented with a history of pain, redness, and watering of the left eye for the last 1 day. There is also photophobia. What is the most probable diagnosis?

Accepted Answer

Keratitis

Answer

Acute, anterior uveitis

Answer

Acute posterior uveitis

Answer

Epidemic keratoconjunctivitis

Question 2

In Herpes zoster keratitis, which of the following clinical presentations is LEAST likely to occur?

Accepted Answer

Sclerokeratitis

Answer

Pseudodendritic keratitis

Answer

Anterior uveitis with endothelial keratitis

Answer

Endothelitis

Question 3

Important in Herpes simplex involvement of the eye are all EXCEPT:

Accepted Answer

Purulent discharge

Answer

Type of lesion

Answer

Corneal anaesthesia

Answer

Iridocyclitis

Question 4

A 20-year-old male presents with sudden onset left eye pain and vision loss. Examination reveals a hazy left cornea. Upon looking down, a bulge is noted in the lower eyelid. Retinoscopy demonstrates a scissoring reflex and a positive oil drop sign in both eyes. What is the diagnosis?

Accepted Answer

Keratoconus

Answer

Corneal dystrophy

Answer

Pathological myopia

Answer

Keratoglobus

Question 5

Posterior polymorphous dystrophy is characterized by which of the following?

Accepted Answer

Corectopia

Answer

Autosomal recessive inheritance

Answer

Blindness in over 90% of sufferers

Answer

Treatment with lamellar corneal grafts

Question 6

Which of the following is NOT an indication for the prosthesis shown in the image?

Accepted Answer

Oral Contraceptive Pills (OCP) - Stage 1 or 2

Answer

Crouzon Disease

Answer

Multiple failed Penetrating Keratoplasty

Answer

Epidermolysis Bullosa Acquisita

Question 7

What is the most common cause of corneal keratitis in soft contact lens users?

Accepted Answer

Pseudomonas keratitis

Answer

Acanthamoeba keratitis

Answer

Corneal erosion

Answer

Herpes simplex keratitis

Question 8

Under hypoxic conditions, which of the following is strongly implicated as a cause of corneal edema?

Accepted Answer

Lactate

Answer

Glycogen

Answer

Carbon dioxide

Answer

Pyruvate

Question 9

Which of the following medications is NOT typically administered as eye drops for a corneal ulcer?

Accepted Answer

Flurometholone

Answer

Chloramphenicol

Answer

Methylcellulose

Answer

Olopatadine

Question 10

KISA% is associated with which of the following conditions?

Accepted Answer

Keratoconus

Answer

Keratoglobus

Answer

Hypermetropia with astigmatism

Answer

Terrien's marginal degeneration

Diseases of the Cornea — MCQs

Diseases of the Cornea — MCQs

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