Soft Contact Lenses — MCQs
A young boy who used to wash his contact lenses in tap water or with unhygienic lens fluid developed keratitis. Microscopy revealed an organism with spiked or star-shaped structures. Identify the correct organism responsible.
Interstitial keratitis is associated with all of the following except:
Which organism is most commonly associated with the wearing of soft contact lenses?
Which of the following statements is false about phacolytic glaucoma?
A patient with contact lens use for the past 2 years presents with the ocular findings shown in the image below. What is the most probable diagnosis?
Keratitis in contact lens wearers is caused by all except?
A 23-year-old woman is diagnosed with chlamydia. Her partner refuses testing. What contact tracing approach is most appropriate?
A patient presents with eye pain, redness, and blurred vision after sleeping in contact lenses. Fluorescein staining reveals a corneal ulcer. What is the most appropriate management?
What is the most common type of cataract found in a newborn?
The Fincham test is used to diagnose which of the following conditions?
Soft Contact Lenses Indian Medical PG Practice Questions and MCQs
Question 1: A young boy who used to wash his contact lenses in tap water or with unhygienic lens fluid developed keratitis. Microscopy revealed an organism with spiked or star-shaped structures. Identify the correct organism responsible.
- A. Balantidium
- B. Pseudomonas
- C. Acanthamoeba (Correct Answer)
- D. Staphylococcus aureus
Explanation: ***Acanthamoeba*** - *Acanthamoeba* is a **free-living amoeba** found in water, soil, and inadequately disinfected contact lens solutions, specifically linked to **keratitis** in contact lens wearers. - Its characteristic morphology, often described as having **spiked or star-shaped structures**, refers to the **acanthopodia** (spine-like pseudopods) that are distinctive features visible microscopically. *Balantidium* - *Balantidium coli* is a **ciliated protozoan** and primarily causes **intestinal infections** (balantidiasis), not keratitis. - It would be distinguished microscopically by its **large size**, **kidney-shaped macronucleus**, and **cilia**, not spiked structures. *Pseudomonas* - *Pseudomonas aeruginosa* is a **bacterium** and a common cause of **bacterial keratitis**, especially in contact lens wearers, but it is not a protozoan. - Microscopically, it would appear as **rod-shaped bacteria**, not organisms with spiked or star-shaped structures. *Staphylococcus aureus* - *Staphylococcus aureus* is a **bacterium** and a frequent cause of various infections, including **bacterial keratitis**. - Under a microscope, it presents as **Gram-positive cocci in clusters**, not as an amoeba with spiked or star-shaped protrusions.
Question 2: Interstitial keratitis is associated with all of the following except:
- A. Syphilis
- B. Acanthamoeba (Correct Answer)
- C. Chlamydia Trachomatis
- D. Herpes Zoster Virus (HZV)
Explanation: ***Acanthamoeba*** - **Acanthamoeba keratitis** is a **suppurative keratitis** characterized by a painful, ring-shaped infiltrate with epithelial ulceration, typically associated with contact lens use and contaminated water exposure. - It causes **ulcerative stromal inflammation**, not the **non-ulcerative deep stromal inflammation** that characterizes classic interstitial keratitis. - **This is NOT a cause of interstitial keratitis.** *Syphilis* - **Congenital syphilis** is the **CLASSIC cause** of bilateral **interstitial keratitis**, often presenting in late childhood with "salmon patch" appearance, photophobia, lacrimation, and eventual ghost vessels. - The inflammation is **non-ulcerative and chronic**, affecting the **deep corneal stroma** with preservation of epithelium. - This is the most important association with interstitial keratitis to remember. *Chlamydia Trachomatis* - **Chlamydia trachomatis** causes **trachoma**, a chronic keratoconjunctivitis leading to **superficial keratitis with pannus formation** (superficial vascularization from the limbus). - The corneal involvement in trachoma is **superficial**, not the deep stromal inflammation seen in classic interstitial keratitis. - While listed in some references, **Chlamydia is NOT a standard cause of interstitial keratitis** in major ophthalmology textbooks. - **Note:** This option is potentially debatable, but Acanthamoeba is the more definitively incorrect answer. *Herpes Zoster Virus (HZV)* - **Herpes zoster ophthalmicus** can lead to **interstitial keratitis** and **disciform keratitis** (immune-mediated stromal inflammation with disc-shaped corneal edema). - Similarly, **HSV (Herpes Simplex Virus)** causes stromal keratitis, a form of interstitial keratitis. - The corneal involvement includes **deep stromal inflammation, scarring**, and potential neurotrophic changes leading to vision impairment.
Question 3: Which organism is most commonly associated with the wearing of soft contact lenses?
- A. Acanthamoeba
- B. Pseudomonas aeruginosa (Correct Answer)
- C. Aspergillus
- D. Staphylococcus aureus
Explanation: ***Pseudomonas aeruginosa*** - This is the **most common bacterial pathogen** causing contact lens-related microbial keratitis, accounting for 30-50% of cases. - Particularly associated with **soft contact lens wear**, it is known for rapid progression and severe corneal ulceration. - Risk factors include **overnight wear**, poor lens hygiene, and contaminated lens storage cases. - Can lead to **sight-threatening keratitis** within 24-48 hours if untreated. *Acanthamoeba* - While strongly associated with contact lens wear (especially poor hygiene and water exposure), it is **much less common** than bacterial causes. - Acanthamoeba keratitis is a severe protozoal infection but has a relatively low incidence (~1-2 per million contact lens wearers). - Characterized by severe pain disproportionate to clinical signs and ring-shaped stromal infiltrate. *Staphylococcus aureus* - A common cause of bacterial keratitis but **less specifically associated** with soft contact lens wear compared to Pseudomonas. - More commonly causes blepharitis and external eye infections. *Aspergillus* - Fungal keratitis is **rarely associated** with contact lens wear in developed countries. - More commonly linked to ocular trauma with vegetative matter in agricultural settings.
Question 4: Which of the following statements is false about phacolytic glaucoma?
- A. Open angle glaucoma
- B. Lens induced glaucoma
- C. Primarily caused by iris-lens contact (Correct Answer)
- D. Seen in hypermature stage of cataract
Explanation: ***Primarily caused by iris-lens contact*** - This statement is **FALSE** because **phacolytic glaucoma** is caused by the leakage of **lens proteins** from a **hypermature cataract** into the **anterior chamber**, not by iris-lens contact. - **Iris-lens contact** is the mechanism in **pupillary block glaucoma** and **acute angle-closure glaucoma**, not in phacolytic glaucoma. - The pathophysiology involves **macrophages** engulfing leaked lens proteins and obstructing the **trabecular meshwork**. *Open angle glaucoma* - This statement is true because **phacolytic glaucoma** is definitively an **open-angle glaucoma**. - It involves obstruction of the **trabecular meshwork** by **macrophages** laden with **lens proteins**, which is an open-angle mechanism. - The angle remains anatomically open but functionally blocked. *Seen in hypermature stage of cataract* - This statement is true because **phacolytic glaucoma** develops when the **lens capsule** of a **hypermature (Morgagnian) cataract** becomes permeable. - This permeability allows **high-molecular-weight lens proteins** to leak into the **aqueous humor**. *Lens induced glaucoma* - This statement is true as **phacolytic glaucoma** is a specific type of **lens-induced glaucoma**, arising from the toxic effects of **leaked lens material**. - Other forms of **lens-induced glaucoma** include **phacomorphic glaucoma**, **lens-particle glaucoma**, and **phacoanaphylactic glaucoma**.
Question 5: A patient with contact lens use for the past 2 years presents with the ocular findings shown in the image below. What is the most probable diagnosis?
- A. Trachoma
- B. Giant Papillary conjunctivitis (Correct Answer)
- C. Ocular Surface Squamous Neoplasia (OSSN)
- D. Vernal Keratoconjunctivitis
Explanation: ***Giant Papillary conjunctivitis*** - The image shows **large, elevated papillae** on the **tarsal conjunctiva**, which are characteristic findings of giant papillary conjunctivitis. - This condition is common among **contact lens wearers**, caused by chronic mechanical irritation and an allergic response to lens material or deposits. *Trachoma* - Trachoma is a **chronic infectious disease** caused by *Chlamydia trachomatis*, leading to scarring of the conjunctiva. - It typically presents with **follicles** in the early stages, followed by **scarring** and **pannus formation**, not the large papillae seen here. *Ocular Surface Squamous Neoplasia (OSSN)* - OSSN refers to a spectrum of conditions from **dysplasia to squamous cell carcinoma** affecting the conjunctiva or cornea. - It usually presents as a **gelatinous, fleshy, or leukoplakic lesion**, often at the limbus, which is distinct from the diffuse papillae shown. *Vernal Keratoconjunctivitis* - Vernal keratoconjunctivitis (VKC) is a **severe form of allergic conjunctivitis** but primarily affects children and young adults with a history of atopy. - While it can cause large papillae (cobblestone papillae), it is not specifically associated with contact lens wear and usually has other systemic allergic manifestations.
Question 6: Keratitis in contact lens wearers is caused by all except?
- A. Chlamydia
- B. Aspergillus
- C. Pseudomonas
- D. Pneumococcus (Correct Answer)
Explanation: ***Pneumococcus*** - While *Streptococcus pneumoniae* (Pneumococcus) can cause bacterial keratitis, it is **classically associated with corneal ulcers following trauma** rather than contact lens wear. - In contact lens-related keratitis, Pneumococcus is **significantly less common** compared to *Pseudomonas*, which dominates as the primary bacterial pathogen in this setting. - Pneumococcal keratitis typically presents with a **well-demarcated, dense purulent ulcer with hypopyon**, often following corneal injury. *Pseudomonas* - **_Pseudomonas aeruginosa_** is **the most common cause of bacterial keratitis in contact lens wearers**, accounting for the majority of severe cases. - It thrives in moist environments such as contaminated contact lens cases and solutions, producing **exotoxins and proteases that cause rapid corneal destruction and tissue melt**. - Presents with a **rapidly progressive, dense stromal infiltrate** with a characteristic **ground-glass appearance** and potential for perforation. *Aspergillus* - **_Aspergillus_ species** are an important cause of **fungal keratitis**, particularly associated with contact lens wear, poor lens hygiene, and contaminated lens solutions. - Fungal keratitis presents with **feathery-edged infiltrates, satellite lesions**, and ring-shaped infiltrates, often requiring antifungal therapy. - More common in tropical climates and agricultural settings. *Chlamydia* - **_Chlamydia trachomatis_** is primarily a cause of **trachoma** (chronic follicular conjunctivitis leading to scarring) and **adult inclusion conjunctivitis**. - While it can cause **superficial punctate keratitis and pannus formation** in trachoma, it is **NOT a typical cause of acute suppurative keratitis in contact lens wearers**. - The acute bacterial and fungal keratitis seen in contact lens wearers is a different clinical entity from chlamydial conjunctivitis/keratopathy.
Question 7: A 23-year-old woman is diagnosed with chlamydia. Her partner refuses testing. What contact tracing approach is most appropriate?
- A. Expedited partner therapy (Correct Answer)
- B. Patient referral only
- C. Contract referral
- D. Provider referral only
Explanation: ***Expedited partner therapy (EPT)*** - This approach allows clinicians to provide medication or a prescription for a partner without a prior medical examination, facilitating treatment when a partner is unwilling or unable to seek care. - It is particularly useful for **chlamydia** and **gonorrhea** to reduce reinfection rates and further transmission. - **Recommended by CDC and WHO** for STI partner management when partners are unlikely to present for care. - *Note: EPT implementation varies by country; in India, partner notification with clinical evaluation is standard practice, but EPT represents the most direct approach when partners refuse testing.* *Patient referral only* - Relying solely on the patient to inform and encourage their partner to seek testing and treatment can be effective but carries a risk of the partner not following through, leading to continued transmission. - This method might be less successful if the partner is uncooperative or unwilling to get tested, as is implied in this scenario. - **Most commonly used approach** in resource-limited settings but has lower success rates. *Contract referral* - Involves the patient agreeing to notify their partner, with the understanding that if the partner does not present for treatment within a specified timeframe, health officials will then intervene. - While it offers a backup, it still relies on initial patient action and may not be immediate enough when a partner is actively refusing testing. - Provides a **safety net** but involves delays in partner treatment. *Provider referral only* - This method involves a healthcare provider directly contacting the partner to inform them of exposure and recommend testing and treatment, respecting patient confidentiality. - This option is generally preferred when there are concerns about the patient's safety or if the patient is unable or unwilling to notify their partner. - More resource-intensive and requires **trained health workers** for partner notification, but ensures partners are reached even if the index patient cannot or will not inform them.
Question 8: A patient presents with eye pain, redness, and blurred vision after sleeping in contact lenses. Fluorescein staining reveals a corneal ulcer. What is the most appropriate management?
- A. Topical antibiotics (Correct Answer)
- B. Oral antibiotics
- C. Topical corticosteroids
- D. Saline irrigation
Explanation: ***Topical antibiotics*** - A **corneal ulcer**, especially in a contact lens wearer, is highly suspicious for **bacterial infection**, necessitating immediate and aggressive topical antibiotic therapy. - **Broad-spectrum antibiotics** (e.g., fluoroquinolones) are often started empirically and adjusted based on culture results. *Oral antibiotics* - **Systemic antibiotics** are generally not indicated for uncomplicated bacterial corneal ulcers, as they don't achieve sufficient concentrations in the cornea to be effective. - They may be considered for severe cases with limbal involvement or scleral extension, or if there is a concern for concurrent systemic infection. *Topical corticosteroids* - **Corticosteroids** are contraindicated in the initial management of suspected infectious corneal ulcers because they can suppress the immune response and worsen the infection. - They may be cautiously used later in treatment to reduce inflammation after the infection is well-controlled. *Saline irrigation* - While helpful for removing foreign bodies or debris, **saline irrigation alone** is insufficient to treat a bacterial corneal ulcer. - It does not eradicate the infection and delaying definitive antibiotic treatment can lead to severe complications.
Question 9: What is the most common type of cataract found in a newborn?
- A. Zonular (Correct Answer)
- B. Nuclear
- C. Snowflake
- D. Cortical
Explanation: **Explanation:** **Zonular (Lamellar) Cataract** is the most common type of congenital cataract. It is characterized by opacification of a specific layer (zone) of the lens fibers, typically surrounding a clear embryonic nucleus. This occurs due to a transient environmental or nutritional insult (such as Vitamin D deficiency or hypocalcemia) during a specific stage of lens development. Because it often allows some light to pass through the clear areas, it is frequently associated with relatively good visual prognosis if managed early. **Analysis of Incorrect Options:** * **Nuclear Cataract:** While common in age-related (senile) cataracts, it is less frequent in newborns. It involves the central core of the lens and is often associated with intrauterine infections like Rubella. * **Snowflake Cataract:** This is a classic finding in **Diabetes Mellitus** (specifically juvenile diabetes). It consists of subcapsular white opacities and is not a standard congenital presentation. * **Cortical Cataract:** This is typically an age-related change characterized by "cuneiform" or wedge-shaped opacities in the lens cortex. It is rarely seen as a primary congenital finding in newborns. **Clinical Pearls for NEET-PG:** * **Most common cause of Congenital Cataract:** Idiopathic (followed by genetic/hereditary factors). * **Most common infection:** Rubella (presents as "Pearls in the center" or dense nuclear cataract). * **Oil droplet cataract:** Classic for Galactosemia. * **Sunflower cataract:** Seen in Wilson’s disease (Chalcosis). * **Management:** If the cataract is visually significant (central opacity >3mm), surgery (Lens aspiration + Primary Posterior Capsulotomy + Anterior Vitrectomy) is ideally performed within the first 4–6 weeks of life to prevent amblyopia.
Question 10: The Fincham test is used to diagnose which of the following conditions?
- A. Open angle glaucoma
- B. Cataract (Correct Answer)
- C. Mucopurulent conjunctivitis
- D. Acute angle closure glaucoma
Explanation: **Explanation:** The **Fincham Test** (also known as the Fincham’s Stenopeic Slit Test) is a clinical method used to differentiate between halos caused by **corneal edema** (as seen in Acute Angle Closure Glaucoma) and those caused by **immature cataract**. 1. **Why Cataract is correct:** In an immature cataract, the opacities in the crystalline lens act as a diffraction grating. When a stenopeic slit is passed across the pupil, the halos **break up into segments** or rotate. This positive Fincham test confirms the halos are lenticular (cataractous) in origin. 2. **Why Acute Angle Closure Glaucoma (AACG) is incorrect:** In AACG, halos are caused by corneal edema (fluid in the epithelium). When the stenopeic slit is moved across the pupil, these halos **remain intact** and do not break up. 3. **Why Open Angle Glaucoma & Mucopurulent Conjunctivitis are incorrect:** These conditions do not typically present with the specific "halo" phenomenon that requires differentiation via Fincham’s test. Mucopurulent conjunctivitis may cause blurred vision due to discharge, but this clears with blinking. **Clinical Pearls for NEET-PG:** * **Mechanism:** Halos in cataract are due to diffraction by lens fibers; in glaucoma, they are due to diffraction by edematous corneal epithelial cells. * **Emsley’s Rule:** Another name for the principle that glaucomatous halos are circular and intact, while cataractous halos are fragmented. * **Differential Diagnosis of Halos:** Always consider AACG, Cataract, and sometimes contact lens overwear (Sattler’s veil).
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