Ophthalmic Surgery Practice Questions

Q: Which laser is used for posterior capsular opacification (PCO)?

Nd:YAG. ***ND-YAG*** - The **Nd:YAG laser** is specifically used for **posterior capsulotomy**, a procedure to treat **posterior capsular opacification (PCO)**, also known as secondary cataract. - It creates a small opening in the opacified posterior capsule using **photodisruption**, which vaporizes the tissue. *Krypton* - **Krypton lasers** are typically used in **photocoagulation** for retinal conditions, such as **diabetic retinopathy** or **retinal tears**. - They are not used for incising ocular tissues like the posterior capsule due to their wavelength and photocoagulative nature. *Argon* - **Argon lasers** are primarily used in **retinal photocoagulation** for conditions like **diabetic retinopathy**, **retinal vein occlusions**, and also for **trabeculoplasty** in glaucoma. - Like krypton lasers, their mechanism of action involves thermal coagulation of tissue, not photodisruption of the posterior capsule. *Diode laser* - **Diode lasers** have various applications in ophthalmology, including **transscleral cyclophotocoagulation** for glaucoma and **retinal photocoagulation**. - They are not used for posterior capsulotomy as their wavelength and energy delivery are unsuitable for this specific procedure.

Q: Method followed to decrease post-op infection in cataract surgery:

Intracameral antibiotics and betadine wash. ***Intracameral antibiotics and betadine wash*** - **Intracameral antibiotics** (e.g., cefuroxime, moxifloxacin) directly target the anterior chamber during surgery, effectively reducing the risk of **endophthalmitis**. - A **betadine (povidone-iodine) wash** of the ocular surface preoperatively significantly reduces bacterial load, preventing introduction of microbes into the surgical field. *Topical antibiotics and sterile draping* - While **topical antibiotics** are important, they may not achieve sufficient intraocular concentrations to prevent deep infection effectively. - **Sterile draping** is essential for maintaining a sterile field but does not address potential intrinsic bacterial flora on the conjunctiva or adnexa as thoroughly as a betadine wash. *Topical antibiotics alone* - **Topical antibiotics** alone are often insufficient to prevent **intraocular infections** because they may not penetrate the eye adequately to eradicate all pathogens. - This approach lacks the comprehensive germicidal action of a **betadine wash** on the ocular surface and the direct intraocular effect of intracameral antibiotics. *Topical antibiotics and sterile instruments* - **Sterile instruments** are a fundamental and non-negotiable part of any surgical procedure to prevent infection from external sources. - However, relying solely on **topical antibiotics** and sterile instruments overlooks the importance of reducing the patient's own **periocular bacterial flora** (addressed by betadine wash) and directly treating potential intraocular contamination (addressed by intracameral antibiotics).

Q: Best irrigating fluid for phacoemulsification is

Balanced Salt Solution (BSS Plus). ***Balanced Salt Solution (BSS Plus)*** - **BSS Plus** is specifically formulated for intraocular use, closely mimicking the electrolyte composition of **aqueous humor**, ensuring minimal corneal edema and damage. - It contains essential ions and bicarbonate, which helps maintain the **physiological pH and osmotic balance** necessary for delicate ocular tissues. *Glycine* - **Glycine** is often used as an irrigant in urological procedures (e.g., TURP) due to its non-conductive properties, but it is **hypo-osmolar** and can cause significant corneal swelling and endothelial damage in the eye. - It is not suitable for intraocular use as it can lead to **cellular toxicity** and metabolic disturbances in ocular tissues. *Normal saline* - While it is an isotonic solution, **normal saline (0.9% NaCl)** lacks the additional electrolytes and buffers present in BSS Plus, making it less physiological for intraocular use. - Prolonged use of normal saline in the eye can lead to **corneal edema** and disruption of the delicate balance required for maintaining corneal clarity during surgery. *Distilled Water* - **Distilled water** is a highly hypotonic solution that would cause immediate and severe **corneal swelling** and endothelial cell damage due to osmotic effects. - Its use would result in irreversible damage to ocular structures and is **contraindicated** for any intraocular procedure.

Q: Type of laser used for capsulotomy is:

Nd:YAG. ***Nd:YAG*** - The **Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet) laser** is the gold standard for performing posterior capsulotomy after cataract surgery due to its **photodisruptive** action. - Its **nanosecond pulses** create plasma and shock waves that effectively cut the opaque posterior capsule with minimal collateral tissue damage. *Argon* - **Argon lasers** are primarily used for **photocoagulation**, such as in treating diabetic retinopathy or retinal tears, due to their ability to create thermal burns. - They are not suitable for capsulotomy as their thermal effect would cause excessive damage and scarring to the surrounding ocular tissues. *Ruby* - The **Ruby laser** was one of the earliest lasers developed but is largely **obsolete** in modern ophthalmology. - It operates at a wavelength not ideal for precise tissue cutting or photodisruption required for capsulotomy. *CO2* - **CO2 lasers** are primarily used in surgery for **tissue ablation** and cutting due to their high absorption by water, leading to surface vaporization. - They are not used for capsulotomy because their wavelength would be heavily absorbed by the ocular media, causing significant damage to the cornea and lens.

Q: On measuring 3.5 to 4 mm posterior to the limbus in a phakic eye and plunging a 30 gauge needle perpendicular to sclera, you pass through

Pars plana. ***Pars plana*** - A 3.5 to 4 mm distance posterior to the limbus in a phakic eye precisely targets the **pars plana**, the safest region for intraocular injections and surgeries to avoid lens damage. - Plunging a needle perpendicular to the sclera at this specific distance allows direct access to the vitreous cavity through the **pars plana**, bypassing critical structures. *Tenon's capsule* - **Tenon's capsule** is a fibrous sheath that envelops the eyeball, and it would be the first layer pierced, but not the final structure accessed for an intraocular procedure at this depth. - While the needle would pass through Tenon's capsule, it is an **extraocular structure** and not the target for safe intraocular access when aiming 3.5-4 mm posterior to the limbus. *Ora serrata* - The **ora serrata** is the jagged anterior termination of the retina and is located approximately 6-8 mm posterior to the limbus in the superior aspect and 5-6 mm inferiorly. - A needle plunged 3.5-4 mm from the limbus would **not reach** the ora serrata and would be positioned anterior to it. *Zonules* - The **zonules of Zinn** are suspensory ligaments that hold the lens in place, originating from the ciliary body and attaching to the lens capsule. - These structures are located more anteriorly within the anterior chamber and behind the iris, and plunging a needle 3.5-4 mm posterior to the limbus would **bypass the zonules entirely**.

Q: Which among the following is the BEST irrigating fluid during ECCE?

Balanced salt solution + glutathione. ***Balanced salt solution + glutathione*** - **Balanced salt solution with glutathione** is considered the best irrigating fluid for ECCE because it closely mimics the **natural aqueous humor**, maintaining corneal endothelial cell health and viability during surgery. - The addition of **glutathione** provides an antioxidant effect, protecting the corneal endothelium from oxidative stress and maintaining its metabolic function during prolonged irrigation. *Ringer lactate* - While **Ringer's lactate** is a balanced electrolyte solution, it lacks the specific components and buffering capacity present in specialized ophthalmic irrigating solutions. - It does not contain **glutathione** or other agents crucial for maintaining corneal endothelial viability and function during intraocular surgery. *Normal saline* - **Normal saline (0.9% NaCl)** lacks essential ions (calcium, magnesium, potassium) and appropriate pH buffering required for intraocular use. - Its use can lead to **corneal edema** and endothelial cell damage due to ionic imbalance and the absence of protective components found in balanced salt solutions. *Balanced salt solution* - A **plain balanced salt solution (BSS)** is a significant improvement over normal saline or Ringer's lactate as it is physiologically balanced for intraocular use, containing essential electrolytes. - However, it lacks the **antioxidant properties of glutathione**, which provides superior protection to corneal endothelial cells during extended surgical procedures.

Q: Most common method of anterior capsulotomy in phacoemulsification?

Capsulorhexis. ***Capsulorhexis*** - **Capsulorhexis** creates a continuous, curvilinear opening in the anterior capsule, which is essential for stable **intraocular lens (IOL)** placement and minimizes the risk of capsular tears during phacoemulsification. - This technique allows for better centration of the IOL and reduces the incidence of **posterior capsule opacification (PCO)**. *Can-opener capsulotomy* - This method involves making multiple small tears in the anterior capsule, resulting in a **serrated edge** that is prone to radial tears. - While historically used, it carries a higher risk of complications like **capsular tears** extending to the posterior capsule. *Envelope capsulotomy* - This term is not a standard or commonly recognized method of anterior capsulotomy in modern phacoemulsification. - Modern techniques prioritize a stable and continuous anterior capsular opening. *Linear capsulotomy* - Involves creating a straight, linear incision in the anterior capsule, which is generally not preferred for phacoemulsification due to its **instability** and higher risk of extension. - This method provides less structural integrity for the remaining capsule compared to a continuous curvilinear capsulorhexis.

Q: A 56 year old patient presents after 3 days of cataract surgery with a history of increasing pain and diminution of vision after an initial improvement. The most likely cause would be:

Endophthalmitis. ***Endophthalmitis*** - **Endophthalmitis** is a severe inflammation of the intraocular fluids (vitreous and aqueous humor), most commonly caused by infection following cataract surgery. - The presentation of **increasing pain** and **diminution of vision** a few days after initial improvement is a classic sign of acute post-operative endophthalmitis. *Central retinal vein occlusion* - **Central retinal vein occlusion (CRVO)** typically causes sudden, painless vision loss. - It is not commonly associated with **increasing pain** or a temporal relationship to recent cataract surgery in this manner. *Posterior capsular opacification (PCO)* - **Posterior capsular opacification (PCO)** develops weeks or months after cataract surgery, not within a few days. - It presents as gradual, painless blurring of vision without significant pain. *Retinal detachment* - **Retinal detachment** typically presents with sudden vision loss, flashes of light (photopsia), and floaters. - While it can occur after cataract surgery, it is less likely to present with **increasing pain** as the primary symptom described.

Q: Which of the following is the optimal position for inserting an IOL during a cataract surgery?

Posterior chamber. **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.

Q: Expulsive choroidal haemorrhage is caused by rupture of:

Short posterior ciliary arteries. ***Short posterior ciliary arteries*** - **Expulsive choroidal hemorrhage** is a rare but devastating complication of intraocular surgery, most commonly cataract surgery. It is characterized by acute severe pain, loss of vision, and rapid prolapse of intraocular contents. - The rapid increase in **intraocular pressure** during surgery, often due to sudden decompression of the globe, can lead to the rupture of these relatively larger, high-pressure vessels, causing a massive hemorrhage. *The choriocapillaris* - The **choriocapillaris** is a dense network of fenestrated capillaries located in the inner choroid, primarily responsible for nourishing the outer retina. - While rupture of the choriocapillaris can lead to hemorrhage, the resulting bleeding is typically less extensive and less "expulsive" compared to that originating from larger, higher-pressure arteries. *Retinal vessels* - **Retinal vessels** are located within the retina itself and are separate from the choroidal circulation. Rupture of retinal vessels typically leads to **vitreous hemorrhage** or **retinal hemorrhage**. - Retinal hemorrhages, while serious, do not typically cause the massive, expulsive bleeding seen with choroidal hemorrhage, as they are not under the same high pressure and do not directly contribute to the choroidal blood volume. *Long posterior ciliary arteries* - The **long posterior ciliary arteries** primarily supply the anterior choroid and iris, running within the suprachoroidal space. - While important for ocular blood supply, their rupture is less commonly associated with the sudden, massive, and expulsive hemorrhage characteristic of expulsive choroidal hemorrhage, which typically involves the more posterior and larger caliber short posterior ciliary arteries.

Question 1

Which laser is used for posterior capsular opacification (PCO)?

Accepted Answer

Nd:YAG

Answer

Krypton

Answer

Argon

Answer

Diode laser

Question 2

Method followed to decrease post-op infection in cataract surgery:

Accepted Answer

Intracameral antibiotics and betadine wash

Answer

Topical antibiotics and sterile draping

Answer

Topical antibiotics alone

Answer

Topical antibiotics and sterile instruments

Question 3

Best irrigating fluid for phacoemulsification is

Accepted Answer

Balanced Salt Solution (BSS Plus)

Answer

Glycine

Answer

Normal saline

Answer

Distilled Water

Question 4

Type of laser used for capsulotomy is:

Accepted Answer

Nd:YAG

Answer

Argon

Answer

Ruby

Answer

CO2

Question 5

On measuring 3.5 to 4 mm posterior to the limbus in a phakic eye and plunging a 30 gauge needle perpendicular to sclera, you pass through

Accepted Answer

Pars plana

Answer

Tenon's capsule

Answer

Ora serrata

Answer

Zonules

Question 6

Which among the following is the BEST irrigating fluid during ECCE?

Accepted Answer

Balanced salt solution + glutathione

Answer

Ringer lactate

Answer

Normal saline

Answer

Balanced salt solution

Question 7

Most common method of anterior capsulotomy in phacoemulsification?

Accepted Answer

Capsulorhexis

Answer

Can-opener capsulotomy

Answer

Envelope capsulotomy

Answer

Linear capsulotomy

Question 8

A 56 year old patient presents after 3 days of cataract surgery with a history of increasing pain and diminution of vision after an initial improvement. The most likely cause would be:

Accepted Answer

Endophthalmitis

Answer

Central retinal vein occlusion

Answer

Posterior capsular opacification (PCO)

Answer

Retinal detachment

Question 9

Which of the following is the optimal position for inserting an IOL during a cataract surgery?

Accepted Answer

Posterior chamber

Answer

Iris clip

Answer

Any of the above

Answer

Anterior chamber

Question 10

Expulsive choroidal haemorrhage is caused by rupture of:

Accepted Answer

Short posterior ciliary arteries

Answer

The choriocapillaris

Answer

Retinal vessels

Answer

Long posterior ciliary arteries

Ophthalmic Surgery — MCQs

Ophthalmic Surgery — MCQs

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