Infection Control in Ophthalmology
Ophthalmic equipment that contacts patients' eyes can transmit pathogens -- including bacteria, viruses, and prions -- between patients. The CPOA is often responsible for ensuring that instruments are properly disinfected between uses. Inadequate disinfection can cause serious, preventable infections, including epidemic keratoconjunctivitis (EKC), corneal ulcers, and rarely, Creutzfeldt-Jakob disease (CJD) from prion-contaminated instruments.
Levels of Disinfection
| Level | What It Eliminates | Example Uses |
|---|---|---|
| Sterilization | All microorganisms including spores | Surgical instruments, items penetrating sterile tissue |
| High-level disinfection (HLD) | All organisms except large numbers of spores | Semi-critical items (contact with mucous membranes) |
| Intermediate-level disinfection | Vegetative bacteria, most viruses and fungi; not all spores | Non-critical items with surface contamination; some semi-critical |
| Low-level disinfection | Most bacteria and viruses; not TB or spores | Environmental surfaces; non-critical items |
Spaulding Classification
The CDC's Spaulding classification categorizes medical items by risk and required disinfection level:
- Critical items (penetrate sterile tissue): require sterilization (e.g., surgical instruments, needles)
- Semi-critical items (contact mucous membranes or non-intact skin): require high-level disinfection (e.g., tonometer tips, contact lens trial kits, gonioscopy lenses)
- Non-critical items (contact intact skin): require low- to intermediate-level disinfection (e.g., slit lamp chin rest, trial frame, slit lamp joystick)
Tonometer Tip Disinfection
The Goldmann applanation tonometer tip contacts the corneal surface and must be disinfected between patients. Recommended methods:
- 3% hydrogen peroxide wipe for 1 minute, then rinse with sterile water and allow to dry
- Sodium hypochlorite (diluted bleach) solution (1:10 dilution), wipe, rinse with sterile water, and allow to dry
- Alcohol wipes (70% isopropyl) for intermediate-level disinfection -- must wipe and allow to air dry for at least 5 minutes; alcohol vapor can damage the corneal epithelium if used while still wet
- Disposable tonometer probe covers (single-use Tono-Pens or ocular tonometer covers) eliminate the need for disinfection between patients
⚠️ Common Mistake: Using an alcohol wipe and immediately placing the tonometer tip on the patient's eye can cause corneal toxicity. Alcohol must fully evaporate before contact. Allow at least 5 minutes after wiping, or rinse with sterile saline before use.
Slit Lamp Disinfection
The slit lamp chin rest and forehead rest contact patients' skin (non-critical items) and should be wiped with a 70% alcohol wipe or equivalent low-to-intermediate disinfectant between patients. Lenses used during the exam (Volk-type fundus lenses, gonioscopy lenses) that contact the cornea are semi-critical and require high-level disinfection.
Epidemic Keratoconjunctivitis (EKC) Precautions
Adenoviral conjunctivitis (EKC) is highly contagious and can survive on surfaces for extended periods. If an EKC-positive patient is examined:
- The tonometer tip and all contact lenses must be high-level disinfected
- All surfaces the patient touched (slit lamp joystick, chin rest) should be disinfected
- The examiner should wash hands thoroughly
- Consider scheduling EKC patients at the end of the day to prevent cross-contamination
Standard Precautions (Universal Precautions)
Standard precautions assume all patients' blood and body fluids may be infectious. The CPOA must:
- Wear gloves when there is potential contact with blood or body fluids (e.g., during procedures involving needles or wounds)
- Perform hand hygiene before and after patient contact (wash hands or use alcohol-based hand rub)
- Use PPE (gloves, mask, eye protection) as appropriate
- Properly dispose of sharps (needles, blades) in labeled sharps containers
- Follow exposure protocols if a needlestick or splash occurs
Autoclave (Steam Sterilization)
Surgical instruments used in the office (such as chalazion curettes, foreign body spuds, or surgical trays) are sterilized by autoclave -- pressurized steam at 121-134°C. Key points:
- Instruments must be cleaned (removing bioburden) before sterilization
- Sterilization indicators (chemical strips or biological spore tests) confirm proper function
- Sterile instruments must be stored in sealed pouches until use
- Date and lot number traceability is required for regulatory compliance
💡 Clinical Tip: Check the expiration or sterility assurance date on packaged sterile instruments before opening. A torn pouch or expired date means the item is considered non-sterile and must be reprocessed.
Key Takeaways
- Disinfection level depends on the Spaulding classification: critical = sterilize; semi-critical = high-level disinfect; non-critical = low-level disinfect
- Tonometer tips are semi-critical and require high-level disinfection between patients
- Alcohol wipes must be fully dry before a tonometer tip contacts the eye to prevent corneal injury
- EKC is highly contagious; strict disinfection of all patient-contact surfaces is required
- Standard precautions apply to all patients, assuming all body fluids are potentially infectious
- Autoclaved instruments must have clean surfaces, valid sterility indicators, and intact packaging