Diseases of the Cornea Practice Questions

Q: Which virus is most commonly associated with disciform keratitis?

Herpes Simplex Virus (HSV). ***Herpes Simplex Virus (HSV)*** - **HSV** is the most common cause of **infectious disciform keratitis**, often following a primary ocular HSV infection or reactivation. - Disciform keratitis caused by HSV is a form of **immune-mediated stromal keratitis**, characterized by corneal edema, inflammation, and potential vision loss. *Rubella Virus* - While Rubella can cause ocular manifestations, such as **congenital cataracts** and **glaucoma** in infants, it is not typically associated with disciform keratitis in adults or children. - **Congenital rubella syndrome** is the primary context for ophthalmic issues related to this virus. *Human Immunodeficiency Virus (HIV)* - HIV can lead to various ocular complications, such as **CMV retinitis**, **Kaposi's sarcoma** of the conjunctiva, and **HIV retinopathy**. - However, HIV itself is **not directly linked** to disciform keratitis. *Hepatitis B Virus (HBV)* - HBV infection primarily affects the **liver** and is not commonly associated with direct ocular infections like keratitis. - Ocular manifestations are rare and often nonspecific, mainly related to systemic immune responses rather than direct viral replication in the eye.

Q: Satellite nodules are typically associated with which of the following conditions?

Fungal corneal ulcer. ***Fungal corneal ulcer*** - **Satellite lesions** (small, isolated infiltrates surrounding a larger central ulcer) are a characteristic feature of **fungal keratitis**, indicating the spread of fungal hyphae. - Unlike bacterial ulcers, fungal ulcers often have a feathery, indistinct margin and can be slow-growing. *Tuberculosis* - Ocular tuberculosis can present with granulomatous inflammation, often involving the uvea or retina, but **satellite nodules** around a corneal ulcer are not typical. - Corneal involvement in tuberculosis is rare and usually manifests as interstitial keratitis or phlyctenular keratitis. *Sarcoidosis* - Ocular sarcoidosis commonly causes **uveitis**, conjunctival nodules, or retinal vasculitis. - While it can cause corneal deposits or band keratopathy, it does not typically present with satellite lesions around a primary corneal ulcer. *Viral ulcer* - Viral corneal ulcers, particularly those caused by **herpes simplex virus**, often present as **dendritic ulcers** or geographic ulcers. - Although epithelial lesions can spread, the distinct **satellite infiltrates** in the stroma seen in fungal infections are not characteristic of viral keratitis.

Q: Which of the following statements about corneal dystrophy is true?

It is typically bilateral.. ***It is typically bilateral.*** - **Corneal dystrophies** are inherited genetic disorders that usually affect both eyes symmetrically. - This bilateral presentation is a key characteristic distinguishing them from other corneal conditions. *It is caused by inflammation.* - **Corneal dystrophies** are primarily genetic and degenerative, not inflammatory. - While inflammation can cause corneal damage (e.g., keratitis), it is not the underlying cause of dystrophy. *It involves neovascularization.* - **Neovascularization** (growth of new blood vessels) is typically a response to chronic inflammation, hypoxia, or infection in the cornea. - It is generally not a feature of primary corneal dystrophies, which are characterized by abnormal deposits or structural changes within the corneal layers. *It is usually unilateral.* - As inherited genetic conditions, **corneal dystrophies** almost always affect both eyes. - Unilateral involvement would suggest a different etiology, such as trauma, infection, or a localized acquired condition.

Q: Herpetic keratitis is treated by which of the following?

Acyclovir. ***Acyclovir*** - **Acyclovir** is an **antiviral agent** that specifically targets the **herpes simplex virus**, which is the causative agent of herpetic keratitis. - It works by inhibiting viral DNA replication, thereby reducing viral load and preventing further damage to the cornea. *Analgesics* - **Analgesics** are used to manage pain but do not address the **viral etiology** of herpetic keratitis. - While they can improve patient comfort, they are not a definitive treatment for the underlying infection. *Atropine* - **Atropine** is a **cycloplegic agent** used to paralyze the ciliary muscle and dilate the pupil, often to reduce pain from ciliary spasms in uveitis. - It does not have **antiviral properties** and is not effective against the herpes virus. *Steroids* - **Corticosteroids** can suppress inflammation but are generally **contraindicated** in active herpetic keratitis, especially in the epithelial form. - They can worsen the viral infection by compromising the immune response, potentially leading to **corneal ulceration** and perforation.

Q: Corneal endothelial cell count is measured by?

Specular microscope. ***Specular microscope*** - A **specular microscope** is specifically designed to provide a high-magnification, non-contact view of the **corneal endothelium**, allowing for direct visualization and counting of endothelial cells. - It measures cell density, morphology, and polymegethism, which are crucial for assessing corneal health, especially before and after intraocular surgeries. *Ophthalmoscope* - An **ophthalmoscope** is used to examine the **fundus** or the back of the eye, including the retina, optic disc, macula, and blood vessels. - It does not have the magnification capabilities required to visualize or count individual corneal endothelial cells. *Synoptophore* - A **synoptophore** is an instrument used to diagnose and treat **strabismus** (eye misalignment) and to assess **binocular vision**. - Its function involves showing different images to each eye to test fusion, suppression, and stereopsis, unrelated to corneal cell count. *Amsler's grid* - **Amsler's grid** is a diagnostic tool used to detect **macular degeneration** and other retinal diseases that affect central vision. - It consists of a grid of straight lines and helps identify distortion or missing areas in the patient's central visual field.

Q: All of the following drugs can result in amorphous whorl-like corneal opacities except:

Chlorpromazine. ***Chlorpromazine*** - Chlorpromazine can cause **corneal and lenticular opacities**, but these are typically **granular, punctate, or stellate in pattern**, NOT amorphous whorl-like opacities. - The deposits are usually **fine, golden-brown pigment granules** in the corneal epithelium and anterior lens capsule, distinctly different from the lipid-based verticillata pattern. - Also associated with **pigmentary retinopathy** in chronic use. *Amiodarone* - **Classic cause of corneal verticillata** (vortex keratopathy) - amorphous, whorl-like opacities radiating from below the corneal center. - Due to **phospholipid accumulation** in corneal epithelial lysosomes. - Present in >90% of patients on long-term therapy; usually **asymptomatic and reversible** on discontinuation. *Chloroquine* - Causes **corneal verticillata** similar to amiodarone, appearing as bilateral whorl-like opacities in the basal epithelium. - Due to **drug-induced lipidosis** with accumulation in corneal epithelial cells. - More commonly known for **bull's eye maculopathy** (retinopathy), but corneal changes occur earlier and are **reversible** upon drug cessation. *Indomethacin* - This NSAID can cause **corneal verticillata** or whorl-like opacities, though less commonly reported than amiodarone or chloroquine. - The corneal deposits are typically **benign and reversible** after discontinuation. - Mechanism involves drug accumulation in corneal epithelium.

Q: Topical fluorescein stain is used in the eye to stain?

Cornea. **Cornea** - Fluorescein staining is primarily used to detect **corneal abrasions**, **ulcers**, or other defects in the corneal epithelium. - The dye stains areas where the **epithelial layer is disrupted**, making them visible under a cobalt blue light. *Retina* - The retina is a light-sensitive layer at the back of the eye and is not directly stained by topical fluorescein. - **Fluorescein angiography**, an invasive procedure where dye is injected intravenously, is used to visualize retinal blood vessels. *Choroid* - The choroid is a vascular layer between the retina and the sclera; it is not directly stained by topical fluorescein. - Its blood flow can be visualized using **indocyanine green angiography**, not topical fluorescein. *Iris* - The iris is the colored part of the eye that controls pupil size and is not stained by topical fluorescein. - While integral to eye function, it does not have the epithelial structure that topical fluorescein is designed to highlight for diagnostic purposes.

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

The ulcer has feathery margins.. ***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

Q: Acute corneal hydrops is seen in:

Keratoconus. ***Keratoconus*** - **Acute corneal hydrops** is a classic complication of advanced **keratoconus**, occurring when a break in **Descemet's membrane** allows aqueous humor to enter the corneal stroma. - This leads to sudden onset of **corneal edema**, pain, and significant vision loss, often presenting with a milky white cornea due to stromal clouding. *Corneal dystrophy* - **Corneal dystrophies** are a group of genetic disorders that affect the clarity and structure of the cornea, typically causing progressive vision loss or recurrent epithelial erosions. - While some dystrophies can lead to corneal edema, **acute hydrops** specifically due to a Descemet's membrane rupture is not a characteristic feature. *Anterior staphyloma* - An **anterior staphyloma** is a bulging scar of the cornea and sclera, usually resulting from severe thinning or perforation, often associated with elevated intraocular pressure. - It is a structural deformation involving the entire globe's anterior segment, distinct from the sudden stromal edema of **corneal hydrops** caused by Descemet's rupture. *Interstitial keratitis* - **Interstitial keratitis** is characterized by non-ulcerative inflammation of the corneal stroma without primary involvement of the epithelium or endothelium, often associated with systemic infections like syphilis or Lyme disease. - It typically results in stromal opacification and vascularization ("salmon patch") but does not involve the acute rupture of Descemet's membrane seen in **hydrops**.

Q: Which is an emergency therapeutic indication of keratoplasty?

Perforated corneal ulcer. ***Perforated corneal ulcer*** - A **perforated corneal ulcer** is an ocular emergency requiring urgent intervention to restore the integrity of the globe and prevent severe vision loss or endophthalmitis. Keratoplasty, in this context, acts as a tectonic graft to seal the perforation. - The emergent nature stems from the high risk of **intraocular infection** and **collapse of the anterior chamber**, which can lead to permanent damage and vision impairment. *Keratoconus* - While severe **keratoconus** can eventually lead to keratoplasty, it is typically an elective procedure performed to improve vision after other treatments like contact lenses are no longer effective. - It is a **slowly progressive condition** that does not usually pose an immediate threat to ocular integrity unless acute hydrops occurs, which itself may require different acute management. *Myopia* - **Myopia**, or nearsightedness, is a refractive error typically corrected with glasses, contact lenses, or elective refractive surgery (e.g., LASIK). - It is not a condition that warrants a **therapeutic or emergency keratoplasty**, as it does not involve structural compromise or disease of the cornea that would necessitate transplantation. *Hypermetropia* - **Hypermetropia**, or farsightedness, is also a refractive error, managed with corrective lenses or elective refractive surgery. - Similar to myopia, it does not involve a corneal disease process that would necessitate a **keratoplasty**, especially not on an emergency basis.

Question 1

Which virus is most commonly associated with disciform keratitis?

Accepted Answer

Herpes Simplex Virus (HSV)

Answer

Rubella Virus

Answer

Human Immunodeficiency Virus (HIV)

Answer

Hepatitis B Virus (HBV)

Question 2

Satellite nodules are typically associated with which of the following conditions?

Accepted Answer

Fungal corneal ulcer

Answer

Tuberculosis

Answer

Sarcoidosis

Answer

Viral ulcer

Question 3

Which of the following statements about corneal dystrophy is true?

Accepted Answer

It is typically bilateral.

Answer

It involves neovascularization.

Answer

It is caused by inflammation.

Answer

It is usually unilateral.

Question 4

Herpetic keratitis is treated by which of the following?

Accepted Answer

Acyclovir

Answer

Analgesics

Answer

Atropine

Answer

Steroids

Question 5

Corneal endothelial cell count is measured by?

Accepted Answer

Specular microscope

Answer

Ophthalmoscope

Answer

Synoptophore

Answer

Amsler's grid

Question 6

All of the following drugs can result in amorphous whorl-like corneal opacities except:

Accepted Answer

Chlorpromazine

Answer

Chloroquine

Answer

Amiodarone

Answer

Indomethacin

Question 7

Topical fluorescein stain is used in the eye to stain?

Accepted Answer

Cornea

Answer

Retina

Answer

Choroid

Answer

Iris

Question 8

Which of the following features is characteristic of a fungal corneal ulcer?

Accepted Answer

The ulcer has feathery margins.

Answer

Symptoms are more prominent than signs.

Answer

The ulcer appears dry and grayish-white.

Answer

The ulcer is associated with diffuse corneal edema.

Question 9

Acute corneal hydrops is seen in:

Accepted Answer

Keratoconus

Answer

Corneal dystrophy

Answer

Anterior staphyloma

Answer

Interstitial keratitis

Question 10

Which is an emergency therapeutic indication of keratoplasty?

Accepted Answer

Perforated corneal ulcer

Answer

Keratoconus

Answer

Myopia

Answer

Hypermetropia

Diseases of the Cornea — MCQs

Diseases of the Cornea — MCQs

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