Astigmatic Keratotomy — 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?
Keratometry is done to assess:
Incision used in the endomeatal approach to the ear?
Which is an emergency therapeutic indication of keratoplasty?
What is regular astigmatism?
Maximum correction of myopia can be done by?
A 15-year-old girl with myopic astigmatism does not want to wear glasses. What is the best alternative for her?
Which is an example of Simple Myopic Astigmatism?
All of the following are true about Keratoconus, except:
Which of the following is used for the treatment of Myopia?
Astigmatic Keratotomy 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: Keratometry is done to assess:
- A. Corneal thickness
- B. Curvature of cornea (Correct Answer)
- C. Corneal sensation
- D. Corneal endothelium
Explanation: ***Curvature of cornea*** - **Keratometry** is specifically designed to measure the **radius of curvature of the anterior surface of the cornea**. - This measurement is essential for detecting and quantifying **astigmatism** and for fitting **contact lenses** and calculating **intraocular lens (IOL) power**. *Corneal thickness* - **Corneal thickness** is measured by **pachymetry**, not keratometry. - Pachymetry is used to assess conditions like **corneal edema** or prior to certain refractive surgeries. *Corneal sensation* - **Corneal sensation** is tested using a fine wisp of cotton or a **corneal aesthesiometer**. - This evaluates the integrity of the **corneal nerves** and blink reflex. *Corneal endothelium* - The **corneal endothelium** is assessed using **specular microscopy** to evaluate cell count, size, and shape. - This is important for surgical planning and monitoring **corneal dystrophies**.
Question 3: Incision used in the endomeatal approach to the ear?
- A. Rosen's incision (Correct Answer)
- B. Wilde's incision
- C. Lempert I incision
- D. Lempert II incision
Explanation: ***Rosen's incision*** - **Rosen's incision** is a common incision used in the **endomeatal approach** to the ear, typically for procedures like **stapedectomy**. - It involves an incision in the **posterior meatal wall**, allowing excellent access to the middle ear structures. *Wilde's incision* - **Wilde's incision** is a **postauricular incision** used for draining subperiosteal abscesses associated with acute **mastoiditis**. - It is not used for an endomeatal approach to the middle ear. *Lempert I incision* - **Lempert I incision** (also known as a **Lempert flap**) is a **tympanomeatal flap** elevated for accessing the middle ear, often in tympanoplasty. - While it provides access to the middle ear, it's a flap rather than a distinct incision name like Rosen's for the overall approach. *Lempert II incision* - **Lempert II incision** generally refers to an extension of the **Lempert I flap**, used for wider exposure in more complex middle ear surgeries. - It is also a flap design rather than the primary incision name for the endomeatal approach.
Question 4: Which is an emergency therapeutic indication of keratoplasty?
- A. Keratoconus
- B. Perforated corneal ulcer (Correct Answer)
- C. Myopia
- D. Hypermetropia
Explanation: ***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 5: What is regular astigmatism?
- A. Astigmatism in which the principal meridians are parallel
- B. Asymptomatic astigmatism
- C. Astigmatism as a result of cataract surgery
- D. Astigmatism where the principal meridians are at a 90-degree angle to each other (Correct Answer)
Explanation: ***Astigmatism where the principal meridians are at a 90-degree angle to each other.*** - In **regular astigmatism**, the two principal meridians of the eye's refractive power are **perpendicular** (90 degrees apart), meaning they are not random. - This perpendicularity allows for correction with **sphero-cylindrical lenses**, as the different focal powers are along well-defined axes. *Astigmatism in which the principal meridians are parallel* - This statement is incorrect as it describes a non-existent or mischaracterized form of astigmatism; for astigmatism to occur, there must be a **difference in curvature** and thus power between two meridians, which cannot be parallel and distinct. - While meridians are typically measured, the concept of **parallel principal meridians** does not align with the definition of astigmatism. *Asymptomatic astigmatism* - This describes the **presence of astigmatism without noticeable symptoms**, not the type of astigmatism itself. - Astigmatism can be asymptomatic, particularly if it is of a **low magnitude**, but this term does not define its optical characteristics. *Astigmatism as a result of cataract surgery* - This refers to **induced astigmatism**, often post-surgical, which can be regular or irregular. - **Surgically induced astigmatism** is a cause, not a classification of astigmatism based on the orientation of its principal meridians.
Question 6: Maximum correction of myopia can be done by?
- A. Radial keratotomy
- B. LASIK (Correct Answer)
- C. Photorefractive keratectomy
- D. Orthokeratology
Explanation: ***LASIK*** - **LASIK (Laser-Assisted In Situ Keratomileusis)** allows for significant correction of high myopia by reshaping the cornea with an excimer laser. - It involves creating a **corneal flap** and then ablating tissue underneath, offering precise and stable vision correction for a wide range of refractive errors. - Among the given corneal refractive procedures, LASIK can correct myopia up to **-10 to -12 D**. *Radial keratotomy* - **Radial keratotomy (RK)** involves making radial incisions in the cornea to flatten it, primarily used for low to moderate myopia (up to -3 to -4 D). - It has a higher risk of **unpredictable outcomes**, induced astigmatism, and glare compared to modern laser procedures. *Photorefractive keratectomy* - **Photorefractive keratectomy (PRK)** involves direct ablation of the corneal surface without creating a flap, which is suitable for moderate myopia (up to -8 to -10 D). - While effective, PRK typically has a **longer recovery period** and more post-operative pain than LASIK. *Orthokeratology* - **Orthokeratology (Ortho-K)** uses specially designed rigid contact lenses worn overnight to temporarily reshape the cornea and correct myopia. - The effect is **temporary**, requiring continuous lens wear to maintain vision correction, and is generally limited to low to moderate myopia (up to -4 to -6 D).
Question 7: A 15-year-old girl with myopic astigmatism does not want to wear glasses. What is the best alternative for her?
- A. LASIK
- B. Spherical Specs
- C. Contact lenses (Toric) (Correct Answer)
- D. FEMTO Lasik
Explanation: ***Contact lenses (Toric)*** - **Toric contact lenses** are specifically designed to correct **astigmatism**, along with myopia or hyperopia, by having different refractive powers in different meridians. - They offer a non-surgical alternative to glasses, addressing the patient's desire not to wear spectacles, and are generally safe and effective for teenagers. *LASIK* - **LASIK (Laser-Assisted In Situ Keratomileusis)** is a surgical procedure to correct refractive errors, but it is not typically recommended for individuals under **18-21 years of age** due to continued eye growth and refractive changes. - The patient's age of 15 makes her an unsuitable candidate for LASIK at this time. *Spherical Specs* - **Spherical spectacles** are designed to correct myopia or hyperopia but cannot adequately correct **astigmatism**, which is a significant component of this patient's refractive error. - The patient also explicitly states she does not want to wear glasses, making this option undesirable. *FEMTO Lasik* - **FEMTO LASIK** is an advanced form of LASIK that uses a femtosecond laser to create the corneal flap, offering higher precision and safety. - However, similar to traditional LASIK, it is a **refractive surgical procedure** and typically not performed on patients younger than **18 years old** due to ongoing eye development.
Question 8: Which is an example of Simple Myopic Astigmatism?
- A. +2.00 sphere
- B. +1.00 -3.00 × 90°
- C. -2.00 sphere
- D. plano -2.00 × 90° (Correct Answer)
Explanation: ***plano -2.00 × 90°*** - This prescription indicates a **spherical equivalent of zero (plano)** in one meridian and **-2.00 diopters of myopia** in the meridian 90 degrees away. - This perfectly fits the definition of **simple myopic astigmatism**, where one principal meridian is emmetropic and the other is myopic. *+2.00 sphere* - This prescription represents **simple hyperopia**, meaning the eye is **farsighted** but without any astigmatism. - All light rays focus behind the retina, and there is no difference in refractive power between the principal meridians. *-2.00 sphere* - This represents **simple myopia**, where the eye is **nearsighted** but without any astigmatism. - All light rays focus in front of the retina, and there is no difference in refractive power between the principal meridians. *+1.00 -3.00 × 90°* - This prescription is an example of **mixed astigmatism**, where one principal meridian is hyperopic (+1.00 D) and the other is myopic (-2.00 D, calculated as +1.00 + [-3.00]). - This differs from simple myopic astigmatism where one meridian is emmetropic.
Question 9: 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 10: 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.
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free