Can a corneal shield be sterilized with ethylene oxide (ETO)?

Can Corneal Shields Be Sterilized with Ethylene Oxide (ETO)?

Yes, corneal shields can be sterilized with ethylene oxide (ETO), as it is efficacious and compatible with heat-sensitive medical devices that contact mucous membranes, though the major drawbacks include long turnaround times, flammability, high toxicity, and carcinogenicity. 1

Classification and Sterilization Requirements

Corneal shields are classified as semi-critical medical devices because they contact mucous membranes (the cornea) without penetrating sterile tissue. 1 According to the Spaulding classification system:

• Semi-critical devices require at minimum high-level disinfection, though sterilization is preferred when feasible 1
• Devices that contact intact mucous membranes and may become contaminated with readily transmissible organisms fall into the intermediate risk category 1

ETO Sterilization Compatibility

Ethylene oxide sterilization is efficacious and compatible with heat-sensitive medical devices, making it suitable for corneal shields that cannot withstand high-temperature steam sterilization. 1 The key considerations include:

Advantages:

• Effective for heat-labile instruments that cannot be autoclaved at high temperatures 1
• Provides complete sterilization rather than just high-level disinfection 1

Critical Drawbacks:

• Long turnaround times that may not be practical for clinical workflow 1
• High toxicity and carcinogenicity requiring proper aeration and handling protocols 1
• Flammability hazards necessitating specialized equipment and safety measures 1

Alternative Sterilization Methods

Not Recommended:

• Steam sterilization: Corneal shields, like other heat-labile ophthalmic devices, cannot withstand high-temperature autoclaving 1
• Hydrogen peroxide sterilization: While effective for some devices, compatibility depends on the specific shield design and manufacturer's instructions 1

Preferred Alternative:

• Liquid chemical sterilization with peracetic acid (PAA): FDA-approved and more practical than ETO, offering powerful sterilization with faster turnaround times 1

Critical Manufacturer Considerations

Always follow the manufacturer's instructions for use (IFU) before selecting any sterilization method. 1 The manufacturer's specifications determine:

• Whether the device is designed for single-use or reprocessing 1
• Which sterilization methods are compatible with the device materials 1
• Required aeration times if ETO is used 1

Clinical Context for Corneal Shield Types

Different corneal shield materials have varying sterilization requirements:

• Collagen corneal shields: Typically designed as single-use devices that dissolve over 12-72 hours and are not intended for reprocessing 2, 3
• Silicone corneal shields: May be reusable depending on manufacturer specifications, requiring appropriate sterilization between uses 4
• Metallic eye shields: Can withstand more aggressive sterilization methods 5

Practical Recommendation

For reusable corneal shields, liquid chemical sterilization with peracetic acid is the most practical solution, offering effective sterilization without the toxicity, long turnaround times, and safety hazards associated with ETO. 1 However, if ETO is the only compatible method per manufacturer's IFU, ensure proper aeration protocols are followed to eliminate toxic residues before patient contact. 1