Which Sterilization Methods Are Suitable for Each Instrument Group?

Please refer to our official manual for a complete guide on sterilization of RUMEX instruments: General Instructions for Care, Cleaning and Sterilization of Reusable Instruments for Ophthalmic Applications.

How do I choose the correct sterilization method for different types of ophthalmic instruments?

Steam autoclaving suits most metal ophthalmic instruments as the preferred, versatile choice. Reserve low-temperature options - like ethylene oxide (EtO) or hydrogen peroxide gas plasma - for heat or moisture-sensitive plastics and rubbers. Avoid flash sterilization for routine use.

Choose a method by balancing instrument material compatibility with process lethality. Key conditions include appropriate temperature, pressure, humidity, and exposure time, validated via Bowie-Dick tests and half-cycle testing per ISO 17665. Ophthalmic tools' narrow lumens (<1mm) demand superior penetration.

Steam Sterilization (Autoclaving)

Principle: Saturated steam under pressure coagulates proteins and kills microorganisms - including tough bacterial spores (e.g., Clostridium difficile). It's the oldest, most reliable, widely used, and cost-effective method, with SAL (sterility assurance level) of 10^-6.

Types of Cycles:

• Gravity Displacement: Steam enters from the top, displacing air from the chamber - a classic method running at 121°C/30 min/15 psi for wrapped loads or 132°C/15 min unwrapped. Ideal for basic stainless steel sets.
• Pre-Vacuum (High-Speed): A vacuum pump evacuates air (down to 1-50 mbar) before steam injection, enabling faster cycles (4 min at 132-134°C) and superior penetration into lumens >0.5mm. Preferred for ophthalmic trays.
• Flash Autoclaving: A high-speed, unwrapped cycle (e.g., 3 minutes at 132°C/30 psi) for emergencies, like when a single instrument contaminates a set. Flash provides no post-cycle shelf life - use immediately. National guidelines (e.g., CDC, AORN) strongly discourage routine use and reject it as a substitute for proper inventory, citing cleaning skips and contamination risks in audits.

Suitable for: Stainless steel and titanium instruments - including forceps, scissors, needle holders, speculums, and reusable cannulas.
Unsuitable for: Heat-sensitive plastics, rubber components (e.g., silicone tips), or instruments with lumens impervious to steam penetration (>500mm long).

Low-Temperature Sterilization

Ethylene Oxide (EtO) Gas

• Principle: A highly toxic alkylating agent that kills microbes by disrupting DNA. Effective sterilization demands precise gas concentration (450-600 mg/L), relative humidity (40-80% RH), temperature (29-65°C), and exposure (3–4 hours), followed by 8-12 hour aeration. SAL matches steam.
• Suitable for: Heat- and moisture-sensitive plastics or rubbers, such as irrigation tubing, phaco handpiece components, or IOL inserters.
• Critical Considerations: EtO is highly toxic (carcinogen), demanding lengthy aeration to off-gas from instruments (residuals >10 ppm risk toxicity). Use only in well-ventilated areas under strict safety controls; EPA regulates emissions.
  

Hydrogen Peroxide Gas Plasma

• Principle: A low-temperature (45-55°C), toxin-free method using hydrogen peroxide vapor (H2O2) activated into plasma radicals to eliminate microorganisms. Byproducts are just harmless oxygen and water; cycle time 45-75 min.
• Suitable for: Devices sensitive to heat and moisture, like polymer-coated forceps or flexible endoscopes.
• Limitations: Ineffective on certain lumens (e.g., metallic ones <3 mm diameter or >400 mm long/cellulose materials). Always consult the manufacturer's Instructions for Use (IFU) for compatibility; not for liquids or powders.
  

WARNING! Gas plasma sterilization is not recommended for RUMEX instruments as delicate instruments might be physically damaged when exposed to low pressure.

Chemical (Cold) Sterilization

• Principle: Employs liquid chemical sterilants like glutaraldehyde (most common, 2-3.4%) or peracetic acid (0.2%).
• Suitability: Glutaraldehyde serves mainly as a high-level disinfectant but sterilizes when instruments immerse for 10–12 hours at room temperature (20-25°C), with efficacy against mycobacteria and spores. Peracetic acid acts faster (12-30 min) but is corrosive.
• Critical Considerations: Glutaraldehyde evaporates fast, emits a strong irritating odor, and risks TASS if residues linger - never ideal for critical intraocular devices, per ASCRS warnings. Monitor immersion timers rigorously; rinse post-exposure.

Flash Sterilization

Flash (immediate-use) sterilization fits only true emergencies - like dropping a one-of-a-kind instrument during a vitreoretomy. Key drawbacks: inadequate cleaning time, no sterile packaging for post-cycle sterility, and unvalidated cycles. Many manufacturers now omit flash instructions, preventing compliance verification. Avoid it entirely for routine sets; track usage to <1% of cycles.

Please refer to our official manual for a complete guide on sterilization of RUMEX instruments: General Instructions for Care, Cleaning and Sterilization of Reusable Instruments for Ophthalmic Applications.