Asepsis and Sterilization in Eye Surgery — MCQs

10 questions

In postoperative intensive care unit, five patients developed postoperative wound infection on the same day. The best method to prevent cross infection occurring in other patients in the same ward is to:

All are methods of sterilization except.

'S-A-F-E program' was initiated for the control of which of the following conditions?

Heat-labile instruments for use in surgical procedures can be best sterilized by what method?

The minimum time required for the sterilization of surgical instruments by moist heat at 134°C is:

All are ophthalmological emergencies except -

SAFE strategy is recommended for-

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

Expulsive hemorrhage in cataract surgery is from?

Q10

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

Asepsis and Sterilization in Eye Surgery Indian Medical PG Practice Questions and MCQs

Question 1: In postoperative intensive care unit, five patients developed postoperative wound infection on the same day. The best method to prevent cross infection occurring in other patients in the same ward is to:

A. Practice proper hand washing (Correct Answer)
B. Disinfect the ward with sodium hypochlorite
C. Fumigate the ward
D. Give antibiotics to all other patients in the ward

Explanation: ***Correct: Practice proper hand washing*** - **Proper hand hygiene** is the **single most effective method** for preventing the transmission of **healthcare-associated infections (HAIs)**, including surgical site infections - It physically removes or inactivates **transient microorganisms** from the hands of healthcare workers, thereby stopping their spread between patients - This is the **gold standard** recommended by **WHO, CDC**, and all major infection control guidelines for preventing **cross-infection** in healthcare settings *Incorrect: Disinfect the ward with sodium hypochlorite* - While disinfection with **sodium hypochlorite** is important for **environmental cleaning**, it is **less effective than hand hygiene** in preventing direct patient-to-patient transmission - Environmental disinfection alone **cannot interrupt the main routes of transmission**, which often involve **direct contact** or contaminated hands of healthcare personnel - This is a **secondary measure**, not the primary prevention strategy *Incorrect: Fumigate the ward* - **Fumigation** is typically used for **terminal disinfection** in specific situations, such as after highly contagious outbreaks, and is **not a routine** or primary method for preventing cross-infection in an active ward - Its effectiveness in preventing day-to-day cross-infection is **limited compared to immediate infection control practices** like hand hygiene - This practice is largely **outdated** in modern infection control protocols *Incorrect: Give antibiotics to all other patients in the ward* - **Prophylactic antibiotic use** in all other patients is **discouraged** due to the risk of **antimicrobial resistance (AMR)** and potential adverse effects - It does **not address the source of infection** or the transmission pathways, and can lead to wider public health issues - This is an **inappropriate primary prevention strategy** that violates antimicrobial stewardship principles

Question 2: All are methods of sterilization except.

A. Filtration
B. Heat
C. Gases
D. Sunlight (Correct Answer)

Explanation: ***Sunlight*** - While sunlight has some **disinfectant** properties due to its **UV radiation**, it is not considered a reliable method of **sterilization** because it cannot kill all forms of microbial life, including bacterial spores. - Sterilization requires the **complete elimination of all viable microorganisms**, which sunlight cannot consistently achieve. *Gases* - Certain gases, such as **ethylene oxide** and **hydrogen peroxide vapor**, are effective **sterilizing agents** used for heat-sensitive materials and medical devices. - These gases penetrate packaging and kill microorganisms by **alkylating proteins** and **nucleic acids**. *Filtration* - **Filtration** is a method of **sterilization** for liquids and gases that cannot withstand heat, by physically removing microorganisms. - Filters with very small pore sizes (e.g., **0.22 micrometers**) can retain bacteria and fungi, even though they do not kill them. *Heat* - **Heat** is one of the most common and effective methods of sterilization, used in various forms like **dry heat** (e.g., sterilization ovens) and **moist heat** (e.g., autoclaving). - **Autoclaving** with **saturated steam under pressure** is particularly effective as it rapidly coagulates and denatures microbial proteins.

Question 3: 'S-A-F-E program' was initiated for the control of which of the following conditions?

A. Ocular trauma
B. Onchocerciasis
C. Refractive error
D. Trachoma (Correct Answer)

Explanation: ***Trachoma*** - The **S-A-F-E program** is a comprehensive strategy developed by the World Health Organization (WHO) for the elimination of blinding **trachoma**. - **S-A-F-E** stands for **Surgery** for trichiasis, **Antibiotics** for infection, **Facial cleanliness**, and **Environmental improvement**. *Ocular trauma* - While ocular trauma is a significant cause of vision impairment, its control and prevention strategies are distinct from the specific interventions of the SAFE program. - Management of ocular trauma focuses on immediate medical attention, surgical repair, and preventive measures like protective eyewear. *Onchocerciasis* - **Onchocerciasis**, also known as river blindness, is controlled primarily through mass drug administration of **ivermectin**, alongside vector control. - This condition is caused by a parasitic worm (**Onchocerca volvulus**) and is not targeted by the SAFE program. *Refractive error* - **Refractive errors** (e.g., myopia, hyperopia, astigmatism) are corrected with spectacles, contact lenses, or refractive surgery. - They are not infectious diseases and do not require the public health interventions outlined in the SAFE program.

Question 4: Heat-labile instruments for use in surgical procedures can be best sterilized by what method?

A. Absolute alcohol
B. Ultraviolet rays
C. Chlorine releasing compounds
D. Ethylene oxide gas (Correct Answer)

Explanation: ***Ethylene oxide gas*** - **Ethylene oxide** is a highly effective **sterilizing agent** that can penetrate packaging and is suitable for **heat-sensitive materials** due to its low-temperature application. - It works by **alkylating microbial proteins and nucleic acids**, leading to the death of all microorganisms, including **spores**. *Absolute alcohol* - While **alcohol** is an effective **disinfectant**, it is not a reliable sterilant as it does not consistently kill **bacterial spores**. - Its efficacy as a disinfectant is also limited by its **rapid evaporation** and inability to penetrate organic matter effectively. *Ultraviolet rays* - **UV radiation** is a surface disinfectant and is not suitable for sterilizing surgical instruments as it has **poor penetration** capabilities and cannot sterilize shadowed or covered areas. - It primarily works by damaging the **DNA of microorganisms**, making it effective for air and surface disinfection but not for complex instruments. *Chlorine-releasing compounds* - **Chlorine compounds** are potent disinfectants, but they are often **corrosive to metals** and can damage delicate surgical instruments upon prolonged exposure. - While effective at killing many microorganisms, they are also **not reliably sporicidal** at concentrations safe for instrument sterilization and may leave residues.

Question 5: The minimum time required for the sterilization of surgical instruments by moist heat at 134°C is:

A. 15 minutes
B. 30 minutes
C. 60 minutes
D. 3 minutes (Correct Answer)

Explanation: ***Correct: 3 minutes*** - At a temperature of **134°C**, the high pressure of **moist heat** (prevacuum sterilization) effectively denatures proteins and destroys all microorganisms, including spores, requiring only **3-4 minutes** of exposure time. - This short duration ensures rapid turnaround time for surgical instruments while achieving complete **sterilization**, making it ideal for urgent or flash sterilization cycles. - This is a standard protocol widely used in hospital autoclaves for wrapped instruments. *Incorrect: 15 minutes* - While 15 minutes is a common sterilization time, it is typically used at a lower temperature of **121°C** (gravity displacement sterilization) for moist heat sterilization. - At 134°C, a 15-minute exposure would be unnecessarily long, consuming more energy and time without additional sterilization benefit. *Incorrect: 30 minutes* - A 30-minute sterilization cycle is excessive for moist heat at **134°C**, indicating a misunderstanding of standard sterilization parameters. - This duration is more typical for sterilization at **121°C** with gravity displacement, or for large/dense loads requiring extended heat penetration time. *Incorrect: 60 minutes* - A 60-minute cycle is far too long for routine sterilization of surgical instruments at **134°C** with moist heat. - Such extended times are generally reserved for **dry heat sterilization** (160-180°C for 60-120 minutes) or very specific difficult-to-sterilize items with complex lumens.

Question 6: All are ophthalmological emergencies except -

A. Endophthalmitis
B. CRVO (Correct Answer)
C. Acute congestive glaucoma
D. CRAO

Explanation: ***CRVO*** - Central Retinal Vein Occlusion (CRVO) is characterized by painless **vision loss** due to retinal hemorrhage and edema, but it is generally *not* considered an immediate, vision-threatening emergency in the same vein as the other options. - While it requires prompt evaluation and management to preserve vision, CRVO allows for a less urgent intervention compared to conditions that can lead to permanent vision loss within hours. *Endophthalmitis* - **Endophthalmitis** is a severe inflammation of the intraocular fluids and tissues, typically caused by infection, and can lead to rapid and irreversible vision loss if not treated urgently. - It presents with pain, redness, reduced vision, and hypopyon (pus in the anterior chamber), necessitating immediate antibiotic treatment and surgical intervention. *Acute congestive glaucoma* - **Acute congestive glaucoma** (acute angle-closure glaucoma) involves a sudden increase in intraocular pressure, causing severe pain, redness, corneal edema, and profound vision loss. - If left untreated, the high pressure can cause irreversible damage to the optic nerve within hours, making it a true ocular emergency. *CRAO* - **Central Retinal Artery Occlusion (CRAO)** is a sudden, painless loss of vision in one eye due to blockage of the central retinal artery, leading to retinal ischemia. - It is an ocular emergency because irreversible retinal damage and vision loss can occur within 90-120 minutes of the occlusion, requiring immediate intervention to restore blood flow.

Question 7: SAFE strategy is recommended for-

A. Diabetic retinopathy
B. Trachoma (Correct Answer)
C. Glaucoma
D. Cataract

Explanation: ***Trachoma*** * The **SAFE strategy (Surgery, Antibiotics, Facial Cleanliness, Environmental improvement)** is the WHO-recommended public health approach for the elimination of **trachoma**, a chronic eye infection caused by *Chlamydia trachomatis*. * This comprehensive strategy addresses both active infection and its blinding sequelae, specifically **trichiasis** (in-turned eyelashes) through surgery. *Diabetic retinopathy* * Management of diabetic retinopathy primarily involves **blood sugar control, regular ophthalmologic exams, laser photocoagulation, and anti-VEGF injections**, not the SAFE strategy. * The focus is on preventing and treating retinal damage caused by **diabetes**, which is distinct from infectious causes. *Glaucoma* * Glaucoma is characterized by **optic nerve damage** and visual field loss, usually due to elevated intraocular pressure, and is managed with **medication, laser therapy, or surgery (e.g., trabeculectomy)**. * It is a **neurodegenerative condition**, not an infectious disease, so the SAFE strategy is not applicable. *Cataract* * Cataracts involve the **clouding of the natural lens** of the eye, leading to blurred vision, and are primarily treated through **surgical removal of the cloudy lens** and implantation of an artificial intraocular lens. * This condition is age-related or can be caused by trauma or disease, but it is **not an infection** for which the SAFE strategy would be relevant.

Question 8: Which among the following is the BEST irrigating fluid during ECCE?

A. Ringer lactate
B. Normal saline
C. Balanced salt solution
D. Balanced salt solution + glutathione (Correct Answer)

Explanation: ***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.

Question 9: Expulsive hemorrhage in cataract surgery is from?

A. Vortex vein
B. Choroidal vein
C. Ciliary artery (Correct Answer)
D. None of the options

Explanation: ***Ciliary artery*** - Expulsive hemorrhage is a rare but devastating complication, typically resulting from the rupture of a **posterior ciliary artery** within the choroid. - This arterial rupture leads to a sudden, massive increase in intraocular pressure and extrusion of intraocular contents. *Vortex vein* - **Vortex veins** drain the choroid, and while their rupture could lead to hemorrhage, it is less likely to cause the highly pressurized, expulsive nature of a choroidal hemorrhage. - Hemorrhage from a vortex vein is generally less severe and less rapid in onset compared to arterial bleeding. *Choroidal vein* - **Choroidal veins** are part of the venous drainage system; bleeding from these vessels would typically be lower pressure and less likely to cause an expulsive hemorrhage. - Venous bleeds are generally slower and do not generate the rapid, violent pressure increase characteristic of expulsive hemorrhage. *None of the options* - This option is incorrect because the rupture of a ciliary artery is the direct cause of expulsive hemorrhage. - The other options are incorrect for the reasons stated above.

Question 10: A 56-year-old patient presents after 3 days of cataract surgery with a history of increasing pain and diminished vision after an initial improvement. The most likely cause would be –

A. Posterior capsular opacification
B. Endophthalmitis (Correct Answer)
C. Central retinal vein occlusion
D. Retinal detachment

Explanation: ***Endophthalmitis*** - The presentation of **increasing pain** and **diminished vision** within days of cataract surgery, following an initial improvement, is highly suggestive of acute **postoperative endophthalmitis**. - This severe **intraocular inflammation** is often caused by bacterial infection introduced during surgery, leading to rapid vision loss if not treated promptly. *Posterior capsular opacification* - This condition typically presents weeks to months or even years after cataract surgery, not within 3 days. - It usually causes **gradual blurring of vision** without pain, unlike the acute symptoms described. *Central retinal vein occlusion* - This condition presents with **sudden, painless vision loss** and a characteristic appearance on fundoscopy (e.g., "blood and thunder" retina). - It is not directly related to cataract surgery and would not typically cause increasing pain. *Retinal detachment* - Symptoms usually include **new floaters**, **flashes of light**, and a **"curtain" or "shadow"** over the field of vision, often developing suddenly and progressing. - While it causes vision loss, it is typically painless and not a direct complication presenting with pain within 3 days post-surgery, especially after initial improvement.

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