Asepsis and Sterilization in Eye Surgery

Asepsis Fundamentals - Sterile Start Secrets

• Asepsis: Practices preventing microbial contamination in surgical environments; aims to reduce pathogen load.
• Sterilization: Process eliminating all viable microorganisms, including resilient bacterial spores. Essential for instruments.
• Core Principles:
  • Strict surgical hand hygiene (scrubbing).
  • Patient skin antisepsis (e.g., 5-10% povidone-iodine).
  • Use of sterile drapes, gowns, gloves.
  • Maintaining an inviolable sterile field.
  • Ensuring instrument sterility (autoclaving, ETO).

⭐ Preoperative instillation of 5% povidone-iodine into the conjunctival cul-de-sac for at least 3 minutes is a critical step in endophthalmitis prophylaxis.

Pre-Op Protocols - Clean Sweep Crew

• Patient:
  • Skin: Povidone-iodine (PI) 5-10% (periorbital, allow contact time); PI 0.5-1% (conjunctival sac, e.g., 5% diluted 1:10).
  • Lashes: Clipped or isolated.
  • Antibiotics: Topical (e.g., Moxifloxacin gtts) pre-operatively.
  • Pupil: Mydriasis/miosis as indicated.
• Team:
  • Scrub: Chlorhexidine 4% or PI 7.5% (timed surgical scrub).
  • Attire: Sterile gown, gloves, mask, cap.
• OR:
  • Air: Positive pressure, HEPA filters (≥0.3 µm, 99.97% efficiency).
  • Surfaces: Cleaned and disinfected.
  • Instruments: Autoclaved and confirmed sterile.

⭐ Conjunctival sac irrigation with 0.5-1% Povidone-iodine (e.g., 5% PI diluted 1:10) for ≥30 seconds contact is a critical step to significantly ↓ endophthalmitis risk. (📌 PI Shield!)

Instrument Sterilization - Germ Warfare Gear

• Goal: Eradicate all microbes (spores too) to prevent endophthalmitis.
• Heat Sterilization Methods:
  • Autoclave (Moist Heat):
    • Standard: 121°C, 15 psi, 15-30 min.
    • Flash (emergency): 134°C, 3 min.
    • Use: Most metals; avoid delicate/sharp.
  • Dry Heat (Hot Air Oven):
    • Temperatures: 160°C for 2 hrs or 170°C for 1 hr.
    • Use: Sharps (less dulling), oils, powders.
• Chemical Sterilization (Cold Methods):
  • Ethylene Oxide (ETO) Gas:
    • Process: Low temp (30-60°C); for heat/moisture-sensitive (IOLs, cryoprobes).
    • Caution: Toxic, requires long aeration.
  • Hydrogen Peroxide Gas Plasma (e.g., Sterrad):
    • Process: Low temp (<50°C), rapid cycle.
    • Use: Delicate, heat-sensitive. Not for cellulose, liquids.
  • Glutaraldehyde (2-4% solution):
    • Sterilization: 6-10 hrs immersion.
    • Use: Heat-sensitive items; rinse thoroughly.
• Radiation Sterilization:
  • Method: Gamma rays, industrial use for disposables (e.g., IOLs, sutures).

⭐ Prions (CJD) need enhanced protocols: Autoclave 134°C (18-60 min) or 1N NaOH soak + autoclave.

Intra-Op Asepsis - No-Bug Zone Ops

• Maintain strict sterile field; address any breach immediately.
• Minimize OR traffic; only essential personnel present.
• Employ "no-touch" technique for instruments and IOLs.
• Isolate surgical site with impervious drapes.
• Utilize positive pressure ventilation and HEPA air filtration.
• Gentle wound irrigation with Balanced Salt Solution (BSS).

⭐ Intraoperative povidone-iodine 0.05% to 0.25% irrigation of the conjunctival sac can further reduce bacterial load during surgery for endophthalmitis prophylaxis.

High‑Yield Points - ⚡ Biggest Takeaways

• Povidone-iodine (5-10%) is crucial for ocular surface antisepsis before surgery.
• Autoclaving (121°C, 15 psi, 15-20 min) is gold standard for surgical instrument sterilization.
• Ethylene Oxide (ETO) sterilizes heat-sensitive materials like IOLs and plastics.
• Preoperative topical antibiotics significantly reduce postoperative endophthalmitis incidence.
• Strict adherence to aseptic techniques (e.g., hand scrubbing, sterile gowning, draping) is mandatory.
• TASS (Toxic Anterior Segment Syndrome) is sterile inflammation linked to sterilization/solution errors, distinct from endophthalmitis.