Corneal Collagen Crosslinking — MCQs
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?
Preferred suture for corneal graft is:
All of the following are true about Keratoconus, except:
Which of the following is a known complication of vernal keratoconjunctivitis?
A lady wants LASIK surgery for her daughter. She asks for your opinion. All the following things are suitable for performing LASIK surgery except:
A lady wants LASIK surgery for her daughter. All the following are indications for performing LASIK surgery, except:
Which of the following is a contraindication to topical steroids?
Which of the following is used for the treatment of Myopia?
Which of the following are treatment modalities for myopia?
Radial keratotomy is used as a treatment modality for what condition?
Corneal Collagen Crosslinking Indian Medical PG Practice Questions and MCQs
Question 1: 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 2: Preferred suture for corneal graft is:
- A. 10-0 nylon (Correct Answer)
- B. 9-0 prolene
- C. 8-0 silk
- D. 7-0 vicryl
Explanation: ***10-0 nylon*** - **10-0 nylon** is the preferred suture material for corneal grafts due to its **monofilament structure**, which reduces the risk of infection and inflammation. - Its **fine gauge** (10-0) minimizes tissue trauma and allows for precise wound approximation, crucial for maintaining corneal clarity and astigmatism control. *9-0 prolene* - While Prolene (polypropylene) is also a monofilament suture, **9-0 Prolene** is typically thicker than 10-0 nylon and may induce more astigmatism. - It is less commonly used for corneal grafts as nylon offers superior handling and knot security for this delicate tissue. *8-0 silk* - **8-0 silk** is a braided, multifilament suture, which can harbor bacteria and lead to increased inflammation and infection risk in the avascular cornea. - It is also thicker than 10-0 nylon, making it less suitable for the precise, fine suturing required in corneal transplantation. *7-0 vicryl* - **7-0 Vicryl** (polyglactin 910) is an absorbable suture, which is generally not suitable for corneal grafts where long-term wound support is required. - The absorption process can cause inflammation and unpredictable changes in suture tension, leading to astigmatism and graft instability.
Question 3: All of the following are true about Keratoconus, except:
- A. Astigmatism
- B. Increased curvature of cornea and Astigmatism
- C. Thick cornea (Correct Answer)
- D. Fleischer's ring
Explanation: ***Thick cornea*** - Keratoconus is characterized by **progressive corneal thinning** and weakening, not thickening. - This corneal thinning leads to a conical protrusion, causing significant visual distortion and irregular astigmatism. *Increased curvature of cornea and Astigmatism* - Keratoconus features **increased corneal curvature** with progressive steepening into a cone-shaped configuration. - This results in **irregular astigmatism**, a hallmark feature causing distorted vision at all distances. *Astigmatism* - **Irregular astigmatism** is a cardinal feature of keratoconus due to the asymmetric corneal shape. - Causes blurred and distorted vision that is difficult to correct with spectacles alone. *Fleischer's ring* - **Fleischer's ring** is an iron deposit ring at the base of the cone in keratoconus, visible on slit-lamp examination. - It represents hemosiderin deposition in the basal epithelial cells and is a characteristic clinical sign of keratoconus.
Question 4: Which of the following is a known complication of vernal keratoconjunctivitis?
- A. Keratoconus (Correct Answer)
- B. Retinal detachment
- C. Vitreous hemorrhage
- D. Cataract
Explanation: ***Keratoconus*** - **Vernal keratoconjunctivitis (VKC)** is a chronic allergic eye condition associated with persistent eye rubbing, which can lead to thinning and bulging of the cornea, a condition known as **keratoconus**. - Long-term inflammation and mechanical stress from allergic reactions and *eye rubbing* contribute to the corneal structural changes seen in keratoconus. - This is the **most common and well-recognized complication** of VKC. *Cataract* - While cataracts can occur in VKC patients (particularly from **chronic topical steroid use** or severe disease with shield ulcers), they are **less common than keratoconus** as a direct complication. - Keratoconus remains the more characteristic and frequently encountered complication specifically associated with the mechanical trauma of eye rubbing in VKC. *Retinal detachment* - **Retinal detachment** is a condition where the retina separates from its underlying support tissues and is typically associated with trauma, high myopia, or diabetic retinopathy, not VKC. - VKC primarily affects the conjunctiva and cornea, and its inflammatory processes do not directly cause retinal detachment. *Vitreous hemorrhage* - **Vitreous hemorrhage** involves bleeding into the gel-like substance that fills the eye and is commonly caused by conditions like diabetic retinopathy or retinal tears, not VKC. - VKC does not involve the posterior segment of the eye in a way that would lead to vitreous hemorrhage.
Question 5: A lady wants LASIK surgery for her daughter. She asks for your opinion. All the following things are suitable for performing LASIK surgery except:
- A. Myopia of 4 Diopters
- B. Age of 15 years (Correct Answer)
- C. Stable refraction for 1 year
- D. Corneal thickness of 600 microns
Explanation: ***Age of 15 years*** - LASIK surgery is generally not recommended for individuals under the age of 18 because their **refractive error** may still be changing. - Ensuring **refractive stability** is crucial for long-term success of the procedure. *Myopia of 4 Diopters* - This level of **myopia** (nearsightedness) is well within the treatable range for LASIK surgery. - LASIK can effectively correct moderate myopia for improved vision. *Stable refraction for 1 year* - **Refractive stability** for at least one year is a critical prerequisite for LASIK, indicating that the patient's prescription is no longer changing significantly. - This stability ensures that the surgical correction will be lasting and accurate. *Corneal thickness of 600 microns* - A corneal thickness of 600 microns is considered **more than adequate** for LASIK surgery, as it allows for the creation of a corneal flap and subsequent ablation without compromising corneal integrity. - The minimum required corneal thickness typically falls around 500 microns, with values above this being favorable.
Question 6: A lady wants LASIK surgery for her daughter. All the following are indications for performing LASIK surgery, except:
- A. Stable refraction for 1 year
- B. Corneal thickness of 600 microns
- C. Age of 15 years (Correct Answer)
- D. Myopia of 4 Diopters
Explanation: ***Age of 15 years*** - LASIK surgery is generally not recommended for individuals under the age of 18, as their eyes and **refractive error** are still developing and stabilizing. - Performing LASIK on a 15-year-old could lead to **regression** of the refractive correction as the eye continues to grow. *Myopia of 4 Diopters* - A **myopia** of 4 Diopters (D) falls within the treatable range for LASIK, which can effectively correct moderate degrees of nearsightedness. - This is a common indication for individuals seeking freedom from glasses or contact lenses. *Stable refraction for 1 year* - **Stable refraction** for at least one year is a crucial criterion for LASIK, ensuring that the patient's prescription is unlikely to change significantly post-surgery. - Unstable refraction could result in suboptimal visual outcomes and the need for further correction. *Corneal thickness of 600 microns* - A **corneal thickness** of 600 microns is considered well within the safe range for LASIK surgery, allowing sufficient residual stromal bed after flap creation and ablation. - Adequate corneal thickness is essential to prevent complications such as **corneal ectasia**.
Question 7: Which of the following is a contraindication to topical steroids?
- A. Dendritic ulcer (Correct Answer)
- B. Herpetic stromal keratitis without epithelial defect
- C. Elevated intraocular pressure
- D. Non-infectious anterior uveitis
Explanation: ***Dendritic ulcer*** - A **dendritic ulcer** is characteristic of **herpes simplex keratitis**, which is an active viral infection of the cornea. - **Topical steroids** are contraindicated because they can suppress the immune response, leading to viral replication, corneal melt, and potentially severe vision loss or perforation. *Herpetic stromal keratitis without epithelial defect* - In cases of **stromal keratitis**, where the infection is deeper and an intact epithelium is present, topical steroids may be used cautiously in conjunction with antiviral agents to reduce inflammation and scarring. - The primary concern with steroids in herpes simplex keratitis is activating viral replication in the presence of an **epithelial defect**, which is not present here. *Elevated intraocular pressure* - **Elevated intraocular pressure** is a known side effect of topical steroid use, especially with prolonged administration, but it is not an absolute contraindication in itself. - It necessitates careful monitoring and may require concurrent glaucoma treatment, but the primary condition needing steroids may still warrant their use. *Non-infectious anterior uveitis* - **Topical corticosteroids** are the **mainstay of treatment** for non-infectious anterior uveitis to reduce inflammation and prevent complications such as synechiae and vision loss. - The benefits of controlling inflammation in uveitis generally outweigh the risks associated with judicious steroid use.
Question 8: Which of the following is used for the treatment of Myopia?
- A. Nd–YAG LASER
- B. Excimer Laser (Correct Answer)
- C. Carbamazepine
- D. SSRI
Explanation: **Explanation:** **Correct Answer: B. Excimer Laser** The **Excimer laser** (Argon-Fluoride gas, 193 nm wavelength) is the gold standard for corneal refractive surgeries like **LASIK, PRK, and SMILE**. It works via **photoablation**, a process where high-energy ultraviolet light breaks molecular bonds in the corneal stroma without generating heat (cold laser). In myopia, the Excimer laser is used to flatten the central cornea, thereby reducing its refractive power so that light focuses accurately on the retina. **Incorrect Options:** * **A. Nd:YAG Laser (1064 nm):** This is a solid-state laser used for **photodisruption**. Its primary uses in ophthalmology include Posterior Capsulotomy (for PCO) and Peripheral Iridotomy (for Angle-Closure Glaucoma). It is not used for reshaping the cornea. * **C. Carbamazepine:** This is an anticonvulsant and the first-line treatment for **Trigeminal Neuralgia**. It has no role in treating refractive errors. * **D. SSRIs (Selective Serotonin Reuptake Inhibitors):** These are antidepressants. In ophthalmology, they are clinically significant because they can occasionally cause mydriasis and precipitate acute angle-closure glaucoma, but they do not treat myopia. **High-Yield Clinical Pearls for NEET-PG:** 1. **Laser Wavelengths:** Excimer (193 nm), Nd:YAG (1064 nm), Argon (514 nm - used for photocoagulation in diabetic retinopathy). 2. **Femtosecond Laser:** Used in "Bladeless LASIK" to create the corneal flap; it operates at 1053 nm. 3. **Contraindications for LASIK:** Thin cornea (<450-480 μm), Keratoconus, and unstable refractive error. 4. **SMILE (Small Incision Lenticule Extraction):** The newest refractive procedure that uses only a Femtosecond laser, eliminating the need for a corneal flap.
Question 9: Which of the following are treatment modalities for myopia?
- A. Radial keratotomy
- B. LASER Keratomileusis
- C. Epikeratophaki
- D. LASER Keratoplasty (Correct Answer)
Explanation: **Explanation:** The treatment of myopia focuses on decreasing the refractive power of the eye, typically by flattening the central cornea. **LASER Keratoplasty** (specifically Excimer laser-based procedures like PRK and LASIK) is the gold standard for surgical correction. It works by photoablative decomposition, where the laser breaks molecular bonds to reshape the corneal stroma with extreme precision, effectively reducing the corneal curvature to focus light directly on the retina. **Analysis of Options:** * **Radial Keratotomy (RK):** While historically used for myopia, it involves making deep radial incisions in the peripheral cornea to flatten the center. It is largely obsolete due to complications like diurnal vision fluctuation and globe instability. * **LASER Keratomileusis:** This is a component of LASIK (Laser-Assisted In Situ Keratomileusis). While technically used, "Keratoplasty" is the broader, more encompassing term used in clinical nomenclature for corneal reshaping surgeries in this context. * **Epikeratophakia:** This involves suturing a pre-lathed donor corneal lenticule onto the surface of the patient's cornea. It was primarily used for aphakia or high myopia in children but is rarely performed today due to poor predictability. **High-Yield Clinical Pearls for NEET-PG:** * **Excimer Laser:** Uses Argon-Fluoride (ArF) gas, emitting UV light at **193 nm**. * **LASIK Criteria:** Stable refraction for 1 year, age >18 years, and a residual stromal bed thickness of at least **250 µm** to prevent corneal ectasia. * **Femtosecond Laser:** Used in "Bladeless LASIK" to create the corneal flap and in **SMILE** (Small Incision Lenticule Extraction) for flapless myopia correction.
Question 10: Radial keratotomy is used as a treatment modality for what condition?
- A. Small degree myopia (Correct Answer)
- B. Progressive non-healing ulcer
- C. High astigmatism
- D. High hypermetropia
Explanation: **Radial Keratotomy (RK)** is a historical refractive surgical procedure used primarily for the correction of **low to moderate degrees of myopia** (typically -1.00 to -4.00 Diopters). ### Why Option A is Correct The procedure involves making deep, non-perforating radial incisions (usually 4 to 8) in the peripheral cornea using a diamond knife. These incisions cause the peripheral cornea to bulge outward under intraocular pressure, which results in a compensatory **flattening of the central cornea**. Since myopia is characterized by an over-refractive or "too steep" cornea, this central flattening reduces the refractive power, allowing light to focus correctly on the retina. ### Why Other Options are Incorrect * **B. Progressive non-healing ulcer:** RK is a refractive procedure, not a therapeutic one. In fact, corneal thinning or infection (keratitis) are contraindications for RK. * **C. High astigmatism:** While "Astigmatic Keratotomy" (limbal relaxing incisions) exists, RK is specifically designed for spherical myopia. High astigmatism requires toric implants or laser-based reshaping. * **D. High hypermetropia:** RK flattens the cornea, which would worsen hypermetropia (which requires steepening). Hypermetropia is treated with thermal keratoplasty or convex lenses. ### High-Yield Clinical Pearls for NEET-PG * **Historical Significance:** RK has largely been replaced by LASIK and PRK due to predictability issues. * **Complications:** A classic side effect is **diurnal fluctuation of vision** (vision changes throughout the day) and **progressive hyperopic shift** (patients become more farsighted years later). * **Structural Integrity:** RK weakens the cornea significantly; patients are at high risk of **globe rupture** following even minor blunt trauma. * **Incision Depth:** Incisions are typically made to 90% of the corneal thickness, sparing the visual axis.
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