Future Trends in Refractive Surgery — MCQs
Which of the following is the optimal position for inserting an IOL during a cataract surgery?
Which of the following is NOT an approach followed in revised NPCB cataract surgeries?
In primary open-angle glaucoma, pilocarpine eye drops lower intraocular pressure primarily by acting on which of the following?
A 15-year-old girl with myopic astigmatism does not want to wear glasses. What is the best alternative for her?
Which antiglaucomatous drug is known to cause spasm of accommodation?
Preferred suture for corneal graft is:
Maximum correction of myopia can be done by?
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:
1mm change in axial length of the eyeball would change the refracting power of the eye by?
Future Trends in Refractive Surgery Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following is the optimal position for inserting an IOL during a cataract surgery?
- A. Iris clip
- B. Posterior chamber (Correct Answer)
- C. Any of the above
- D. Anterior chamber
Explanation: **Posterior chamber** - The **posterior chamber** is the optimal position due to its proximity to the natural lens position, offering the best optical outcomes and minimizing complications. - Placing the IOL in the posterior chamber, typically within the **capsular bag**, provides excellent stability and reduces the risk of long-term issues like inflammation and glaucoma. *Iris clip* - **Iris-clip IOLs** are placed by clipping the lens to the iris, a technique primarily used when capsular support is inadequate. - While they can provide good visual acuity, they carry a higher risk of complications such as **uveitis-glaucoma-hyphema (UGH) syndrome** and endothelial cell loss compared to posterior chamber IOLs. *Anterior chamber* - **Anterior chamber IOLs** are placed in front of the iris and are generally reserved for cases where there is no adequate posterior capsular support. - They are associated with a higher incidence of complications like **corneal endothelial damage**, glaucoma, and peripheral anterior synechiae. *Any of the above* - This option is incorrect because while all mentioned positions can technically accommodate an IOL, they are not equally optimal or preferred. - The choice of IOL position depends on factors like **capsular support**, the patient's ocular health, and the surgeon's expertise, but the posterior chamber is overwhelmingly the gold standard when feasible.
Question 2: Which of the following is NOT an approach followed in revised NPCB cataract surgeries?
- A. Mobile surgical camps
- B. Consistent follow-up care
- C. Fixed-site surgical treatment alone (excluding camps) (Correct Answer)
- D. Standardized distribution of resources
Explanation: ***Fixed-site surgical treatment alone (excluding camps)*** - The revised **National Programme for Control of Blindness and Visual Impairment (NPCBVI)** adopts a **multi-pronged integrated approach** combining both fixed-site facilities and mobile outreach camps. - Relying **exclusively on fixed-site treatment** without mobile camps is **not the strategy** of the revised program, as this would limit access for rural and underserved populations. - The program emphasizes **both institutional capacity** (fixed sites at district hospitals and eye hospitals) **and community outreach** (mobile surgical camps) working together. *Mobile surgical camps* - **Mobile camps** are a crucial strategy in the revised NPCB to reach underserved populations in rural and remote areas. - They enhance **accessibility to care** and increase surgical coverage, particularly in areas without nearby fixed facilities. - Camps are conducted with **quality standards** and linked to fixed sites for follow-up care. *Consistent follow-up care* - **Comprehensive follow-up** is a cornerstone of the revised NPCB to ensure positive outcomes and address complications. - This includes **post-operative care protocols** at both camp and fixed-site surgeries to reduce morbidity. - Follow-up mechanisms help achieve the program's goal of **quality cataract surgery outcomes**. *Standardized distribution of resources* - The revised NPCB promotes **equitable and efficient allocation** of resources to ensure quality cataract services across regions. - This includes distribution of **equipment, consumables, trained personnel, and funding** based on need and surgical load. - Resource standardization helps maintain **quality benchmarks** across different service delivery models.
Question 3: In primary open-angle glaucoma, pilocarpine eye drops lower intraocular pressure primarily by acting on which of the following?
- A. All of the options
- B. Trabecular meshwork
- C. Ciliary epithelium
- D. Longitudinal fibres of the ciliary muscle (Correct Answer)
Explanation: ***Longitudinal fibres of the ciliary muscle***- Pilocarpine is a **muscarinic agonist** that contracts the **longitudinal fibers of the ciliary muscle** [1, 3].- This contraction pulls on the **scleral spur**, separating the **trabecular meshwork** sheets, which increases conventional **aqueous humor outflow** [2, 3].*Trabecular meshwork*- While the **trabecular meshwork** is the site where aqueous humor exits the eye, pilocarpine primarily acts on the ciliary muscle to **indirectly affect** the meshwork's outflow facility [2, 3].- Pilocarpine does not directly alter the structure or function of the trabecular meshwork cells.*Ciliary epithelium*- The **ciliary epithelium** is responsible for **aqueous humor production** [1, 2].- Pilocarpine primarily affects **outflow**, not production, through its action on the ciliary muscle [1, 2].*All of the options*- Pilocarpine does not act on **all** these structures; its primary mechanism is through the ciliary muscle to enhance outflow.- It has no direct significant effect on **ciliary epithelium** or direct action on the **trabecular meshwork** itself.
Question 4: 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 5: Which antiglaucomatous drug is known to cause spasm of accommodation?
- A. Timolol
- B. Pilocarpine (Correct Answer)
- C. Dorzolamide
- D. Latanoprost
Explanation: ***Pilocarpine*** - **Pilocarpine** is a **direct-acting muscarinic agonist** that contracts the **ciliary muscle**. - Contraction of the ciliary muscle leads to **accommodation spasm** and a forward movement of the **iris-lens diaphragm**, which also helps to open the **trabecular meshwork**, facilitating aqueous outflow. *Timolol* - **Timolol** is a **beta-blocker** that reduces aqueous humor production by blocking beta-adrenergic receptors on the ciliary epithelium. - It does not directly affect the **ciliary muscle** or cause accommodation spasm. *Dorazolamide* - **Dorzolamide** is a **carbonic anhydrase inhibitor** that reduces aqueous humor production. - Its mechanism of action does not involve the ciliary body's mechanical action and therefore does not cause **accommodation spasm**. *Latanoprost* - **Latanoprost** is a **prostaglandin analog** that increases uveoscleral outflow of aqueous humor. - It does not directly affect the ciliary muscle's contraction or cause **accommodation spasm**.
Question 6: 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 7: 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 8: 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 9: 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 10: 1mm change in axial length of the eyeball would change the refracting power of the eye by?
- A. 1D
- B. 2D
- C. 3D (Correct Answer)
- D. 4D
Explanation: ***3D*** - A 1mm change in the **axial length** of the eyeball leads to an approximate **3 diopter (D) change** in the refractive power of the eye. - This relationship is crucial for understanding **refractive errors** like myopia (if the eyeball is too long) or hyperopia (if it's too short). *1D* - A 1D change in refractive power corresponds to a much larger change in the **focal length** of the eye, not typically 1mm in axial length. - This value is too small to reflect the significant impact of a 1mm axial length alteration on the eye's focusing ability. *2D* - While a direct relationship exists, 2D is an **underestimation** of the actual refractive change caused by a 1mm alteration in axial length. - This value would imply a less sensitive optical system than the human eye. *4D* - A 4D change would represent an **overestimation** of the refractive power change for a 1mm alteration in axial length. - Such a high value is generally seen with more substantial anatomical variations or surgical interventions.
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