Diseases of the Cornea Practice Questions

Q: Corneal sensations are decreased in all of the following conditions except:

Recurrent corneal erosion syndrome. ***Recurrent corneal erosion syndrome*** - This condition involves **defective adhesion** of the corneal epithelium to the underlying Bowman's layer and basement membrane, leading to sudden, severe pain upon waking. - While it causes **pain** and **epithelial defects**, it does not primarily involve nerve damage or decreased corneal sensation; rather, episodes are often very painful due to exposed nerve endings. *Herpetic keratitis* - Caused by the **herpes simplex virus (HSV)**, which can infect the trigeminal nerve and lead to **trophic changes** in the cornea. - This viral infection often results in **significant reduction** or loss of corneal sensation, making the eye more vulnerable to trauma and delayed healing. *Neuroparalytic keratitis* - This condition is also known as **neurotrophic keratitis** and results from damage to the **trigeminal nerve**, which supplies sensation to the cornea. - Loss of corneal sensation leads to impaired reflex tearing and blinking, making the cornea susceptible to epithelial breakdown and ulceration due to lack of protective mechanisms. *Leprosy* - In ocular leprosy, the **Mycobacterium leprae** directly invades the ciliary nerves, significantly impairing corneal sensation. - This reduced sensation in leprosy patients increases the risk of **corneal ulcers** and opacification due to undetected foreign bodies and trauma.

Q: Corneal tattooing is done by ?

India ink. ***India ink*** - **India ink (carbon black)** is the traditional and most commonly used pigment for corneal tattooing due to its stable black color and inert properties. - It is applied to the **corneal stroma** to mask corneal opacities or for cosmetic purposes in cases of unsightly leucomatous corneal scars. - India ink has been the **gold standard** for corneal tattooing since the 19th century. *Gold chloride* - While **gold preparations** (including platinum-gold) have been used historically for corneal tattooing, they are much less common than India ink. - Gold chloride specifically is not the standard or preferred agent for this procedure. - India ink remains the pigment of choice due to better cosmetic results and established safety profile. *Titanium chloride* - **Titanium chloride** is a corrosive chemical and is not used in corneal tattooing; its application would cause severe damage to the delicate corneal tissue. - It is primarily used in industrial applications and chemical synthesis, not in ophthalmic procedures. *Aluminium chloride* - **Aluminium chloride** is an astringent and antiseptic, often used in dermatological products, but it is not a tattooing pigment for the cornea. - Its chemical properties would be highly irritating to the eye and potentially damaging to corneal cells.

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: 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: 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: 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

Question 1

Corneal sensations are decreased in all of the following conditions except:

Accepted Answer

Recurrent corneal erosion syndrome

Answer

Neuroparalytic keratitis

Answer

Leprosy

Answer

Herpetic keratitis

Question 2

Corneal tattooing is done by ?

Accepted Answer

India ink

Answer

Titanium chloride

Answer

Aluminium chloride

Answer

Gold chloride

Question 3

Herpetic keratitis is treated by which of the following?

Accepted Answer

Acyclovir

Answer

Analgesics

Answer

Atropine

Answer

Steroids

Question 4

Corneal endothelial cell count is measured by?

Accepted Answer

Specular microscope

Answer

Ophthalmoscope

Answer

Synoptophore

Answer

Amsler's grid

Question 5

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

Accepted Answer

Fungal corneal ulcer

Answer

Tuberculosis

Answer

Sarcoidosis

Answer

Viral ulcer

Question 6

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 7

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 8

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

Accepted Answer

Chlorpromazine

Answer

Chloroquine

Answer

Amiodarone

Answer

Indomethacin

Question 9

Topical fluorescein stain is used in the eye to stain?

Accepted Answer

Cornea

Answer

Retina

Answer

Choroid

Answer

Iris

Question 10

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.

Diseases of the Cornea — MCQs

Diseases of the Cornea — MCQs

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