Ophthalmic Surgery — MCQs

Ophthalmic Surgery Indian Medical PG Practice Questions and MCQs

Question 141: Phacoemulsification incision is at what location?

A. Sclera
B. Sclero-corneal junction
C. Cornea (Correct Answer)
D. None of the options

Explanation: ***Correct: Cornea*** - The standard incision for **modern phacoemulsification** is a small (2.2-2.8mm), self-sealing **clear corneal incision**. - This incision is typically placed **1-2mm anterior to the limbus** in the temporal quadrant. - **Advantages:** Quicker healing, minimal induced astigmatism, reduced bleeding, sutureless technique, and excellent visualization. - Clear corneal incisions have become the **gold standard** for phacoemulsification since the 1990s. *Incorrect: Sclero-corneal junction* - While historically used for **limbal incisions** in traditional extracapsular cataract extraction (ECCE), this location is less common for modern phacoemulsification. - **Disadvantages:** Increased risk of bleeding from limbal vessels, potentially higher induced astigmatism, and longer healing time. - Some surgeons still use limbal or near-limbal approaches, but clear corneal incisions are preferred. *Incorrect: Sclera* - A primary incision through the **sclera alone** is not standard for phacoemulsification. - Scleral incisions may be used as **secondary port incisions** for instrument access or in specific surgical situations (e.g., combined procedures). - **Disadvantages:** Increased bleeding risk, poor visualization (non-transparent tissue), and typically requires suturing. *Incorrect: None of the options* - This is incorrect as **cornea** is definitively the correct location for standard phacoemulsification incisions in modern cataract surgery.

Question 142: Which of the following is the most important factor in the prevention of endophthalmitis in cataract surgery?

A. Preoperative preparation with povidone iodine (Correct Answer)
B. One week antibiotic therapy prior to surgery
C. Trimming of eyelashes
D. Use of intravitreal antibiotics

Explanation: **Preoperative preparation with povidone iodine** - **Povidone-iodine (5%)** applied to the ocular surface is the **single most evidence-based intervention** for preventing endophthalmitis in cataract surgery. - Multiple randomized controlled trials, including the **ESCRS study**, demonstrate up to **75% reduction** in endophthalmitis risk with proper povidone-iodine antisepsis. - It rapidly reduces bacterial load on the conjunctiva and periocular skin, which are the primary sources of intraocular contamination. *One week antibiotic therapy prior to surgery* - Prolonged preoperative antibiotic therapy is **not recommended** and lacks evidence for reducing endophthalmitis. - Can lead to **antibiotic resistance** and disruption of normal ocular flora without proven benefit. - Current guidelines do not support routine preoperative systemic or prolonged topical antibiotic prophylaxis. *Trimming of eyelashes* - **Not routinely recommended** and may actually increase bacterial counts temporarily due to microtrauma. - While maintaining a clean surgical field is important, eyelash trimming has **no proven benefit** in reducing endophthalmitis rates. - Good draping technique is more important than eyelash manipulation. *Use of intravitreal antibiotics* - **Intravitreal antibiotics** are injected into the vitreous cavity and are used for **treating established endophthalmitis**, not for prophylaxis. - For prophylaxis, **intracameral antibiotics** (e.g., cefuroxime or moxifloxacin injected into the anterior chamber at surgery end) are sometimes used, but they are adjunctive measures, not the primary preventive intervention. - **Povidone-iodine antisepsis** remains the most critical and cost-effective prophylactic measure with the strongest evidence base.

Question 143: Which of the following lasers is NOT used in laser trabeculoplasty?

A. Argon laser
B. Diode laser
C. Nd: YAG laser, 532nm
D. Nd: YAG laser, 1064nm (Correct Answer)

Explanation: ***Nd: YAG laser, 1064nm*** - The **1064nm wavelength Nd:YAG laser** is primarily used for procedures like **posterior capsulotomy** or **iridotomy**, where its photodisruptive effect is desired. - This wavelength is not absorbed by the pigmented cells of the trabecular meshwork, making it ineffective for **trabeculoplasty**. *Nd: YAG laser, 532nm* - The **frequency-doubled Nd:YAG laser (532nm)**, also known as a **green laser**, is effectively used in **selective laser trabeculoplasty (SLT)**. - It targets **melanin-containing cells** in the trabecular meshwork, causing selective photothermolysis without coagulating adjacent non-pigmented tissue. *Argon laser* - The **argon laser** is historically significant and is used in **argon laser trabeculoplasty (ALT)**. - It creates **thermal coagulation** of the trabecular meshwork, leading to tissue contraction and increased outflow. *Diode laser* - **Diode lasers** are used in **diode laser trabeculoplasty (DLT)**. - They also utilize a **thermal effect** on the trabecular meshwork to improve aqueous outflow.

Question 144: Posterior capsular opacification (PCO) is treated by which laser?

A. Argon laser
B. CO2 laser
C. Excimer
D. Nd YAG (Correct Answer)

Explanation: ***Nd YAG*** - **Nd:YAG (neodymium-doped yttrium aluminum garnet) laser** is the treatment of choice for posterior capsular opacification (PCO). - It uses **photodisruption** to create an opening in the opacified posterior capsule, restoring clear vision. *Argon laser* - **Argon laser** is primarily used for procedures like **panretinal photocoagulation (PRP)** in diabetic retinopathy or for certain types of glaucoma. - It operates by **photocoagulation**, which involves thermal destruction of tissue, unsuitable for the delicate capsular incision needed for PCO. *CO2 laser* - **CO2 lasers** are used in various surgical fields for cutting and ablating soft tissues, but not for intraocular procedures like PCO. - They produce **infrared light** that is strongly absorbed by water, making them suitable for surface tissue removal rather than precise incisions within the eye. *Excimer* - The **excimer laser** is primarily used in **refractive surgery** (e.g., LASIK, PRK) to reshape the cornea. - It operates by **photoablation**, precisely removing tissue without significant heat damage, but it is not used to treat PCO.

Question 145: A crucial step in the phacoemulsification procedure for a 70-year-old man scheduled for cataract surgery is which of the following?

A. Scleral buckling
B. Corneal transplantation
C. Continuous curvilinear capsulorrhexis (Correct Answer)
D. Trabeculectomy

Explanation: ***Continuous curvilinear capsulorrhexis*** - This step creates a smooth, continuous, and appropriately sized opening in the **anterior lens capsule**, which is crucial for the safe and effective removal of the cataractous lens material. - A well-executed capsulorrhexis ensures the **intraocular lens (IOL)** can be stably implanted within the capsular bag, minimizing complications like IOL decentering. *Scleral buckling* - **Scleral buckling** is a surgical procedure primarily used to repair **retinal detachments**, not for cataract removal. - It involves placing a silicone band on the outer surface of the sclera to indent the eye wall, supporting the retina. *Corneal transplantation* - **Corneal transplantation** (keratoplasty) is performed to replace a diseased or damaged cornea, typically for conditions like **keratoconus** or corneal scarring. - It is not a component of routine cataract surgery. *Trabeculectomy* - **Trabeculectomy** is a surgical procedure to treat **glaucoma** by creating a new drainage pathway for aqueous humor, thereby reducing intraocular pressure. - It is unrelated to the process of cataract extraction.

Practice by Chapter

Surgical Anatomy of Eye

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Asepsis and Sterilization in Eye Surgery

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Anesthesia in Ophthalmic Surgery

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Cataract Surgery Techniques

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Corneal Surgeries

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Glaucoma Surgeries

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Oculoplastic Surgeries

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Vitreoretinal Surgeries

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Strabismus Surgery

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Refractive Surgery

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Ocular Oncology Surgeries

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Management of Surgical Complications

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