INTRODUCTION

Optometrists have an obligation to take reasonable precautionary measures to ensure that their patients and staff are not exposed to infection, while attending or working in the practice. Understanding the vectors and the mechanism of the spread of infection will assist them in minimising the risk of transmission of infection in the optometric practice.

WHY IS INFECTION CONTROL IMPORTANT?

Patients, and all staff at an optometric practice are exposed to common items such as door handles, pens and working surfaces. Also, all patients are exposed to the same equipment chin rests, forehead rests and instrument surfaces. Research has shown that the majority of people simply do not wash their hands after visiting the toilet. In addition, the world is seen as a global village, making the spread of infections and illnesses so easily communicable.

All optometrists need to be aware of the mechanism of infection and cross infection. In optometric practice, infection may be transmitted from patient to staff, staff to patients, patient to patient and staff to staff by direct contact, contamination of furniture, equipment or instruments in the practice.

Optometrists, as primary health practitioners, are now providing an expanded scope of service in the treatment and management of eye diseases and eye injuries. Many eye diseases are manually transmissible. There are several instances in which optometrists may be exposed to blood, tears and mucous membranes or to infection. Rigorous attention to infection control is warranted in the following circumstances: removal of foreign bodies, assessment of patients with ocular trauma, assessment of patients with red eyes (especially conjunctivitis), assessment of patients with microbial keratitis, eye irrigation, removal of eyelashes, expression of meibomian glands, expressing hordeola, lancing cysts, contact lens fitting, and assessment of patients who are incontinent. Some communicable diseases that could be encountered in optometric practice are human immunodeficiency virus (HIV)/(AIDS), hepatitis A, B and C, tuberculosis, measles, mumps, rubella, chicken pox, shingles, mononucleosis (glandular fever), herpes, influenza, impetigo, adenovirus and Creutzfeld-Jakob Disease (CJD). HIV has been isolated from the tears, contact lenses and ocular tissues. However, there is no evidence of transmission through these. Infection requires direct contact between blood/body fluids and mucous membranes or damaged skin for example, through sexual contact or sharing needles and/or syringes with an infected person, through transfusions of infected blood or blood clotting factors. Injuries from needles containing HIV-infected blood or infected blood entering an open cut or a mucous membrane have also been reported as causing HIV infection. Hepatitis B surface antigen may be present in the conjunctival fluid and there is a risk that it may be transferred to a tonometer or contact lenses. There is no evidence that it is a significant risk in optometric practice. Similarly, there is no evidence of CJD transmission by contact with intact skin. As there is lymphoid tissue in the cornea, there is a theoretical possibility of transmission of vCJD and other forms of CJD between patients through ophthalmic devices that contact the eye, for example, diagnostic contact lenses and tonometers. Such transmission is described as ‘highly improbable’. Adenoviruses are highly contagious and can survive outside the host for long periods, even on dry surfaces.

INFECTION AND STERILISATION CONTROL MEASURES

Optometrists should be familiar with terminology that is used to describe infection control procedures and measures.

A ‘hygienic’ state is a state of cleanliness that offers little or no threat to health.

‘Sanitary conditions’ are those that are physically clean and healthy. ‘Cleaning’ is the removal of foreign material using water and detergents or enzymatic products. Cleaning of instruments is an essential pre-requisite, as organic material such as make-up, dried mucous and tears, may harbour infective organisms. Cleaning may require scrubbing of all surfaces of an instrument to remove debris. Insoluble deposits may require utilisation of isopropyl alcohol, however, alcohol can damage some materials, so its use will depend on the type of material to be cleaned.

‘Disinfection’ is the term used for the inactivation of virtually all pathogenic micro-organisms, but not necessarily all microbial forms. For example, bacterial endospores, fungi, protozoa. Disinfection is usually achieved using thermal (heat and water) or chemical means.

‘Sterilisation’ is usually achieved through autoclaving. This involves exposure of the item to high temperature and pressure, when all viable micro-organisms are eliminated, including bacterial spores.

‘Reprocessing’ is the process of cleaning and disinfection and/or sterilisation of a device that is to be reused.

Patients with short-term infectious illnesses should be treated for the infection first and asked to reschedule their appointment for refraction. Optometrists and staff with infectious diseases need to be aware of the precautions to take to avoid the transmission of disease when dealing with patients and the conditions that should exclude them from attending work. Examples include influenza and conjunctivitis. Patients with influenza should be provided with tissues and asked to use them to cover the nose and mouth when coughing or sneezing and dispose of them immediately into a hands-free waste receptacle.

Hand-washing is considered to be the most important measure in preventing the spread of infection in all healthcare settings. The prevalence of infection decreases as hand hygiene is improved. In light of this, the KZN Department of Health has formulated a chart to demonstrate proper handwashing.  The aim of hand-washing is to remove transient flora that colonise the superficial layers of the skin, which are most frequently associated with healthcare-associated infections. Usually, resident flora is attached to deeper layers of the skin and are more resistant to removal, but are less likely to cause infection. Hand-washing must be performed before and after significant contact with any patient and after activities that are likely to cause contamination, for example, handling food, emptying waste paper baskets, going to the toilet, blowing one’s nose. Hand-washing should also be performed after the removal of gloves. When consulting patients, optometrists must avoid touching their own face, nose, mouth and eyes. Hand-basins should be fitted in all consulting rooms and locations, where contact lenses may be inserted or removed and must be kept clean. When redesigning the office, consider elbow or foot controls to regulate the flow of water. Hand hygiene products, in order from most to least effective, are alcohol formulations, chlorhexidine, iodophors, triclosan, plain soap. Ordinary soap is not recommended for use by health-care workers, as it has minimal antimicrobial activity. It can remove loosely adherent transient bacteria and it can become contaminated with gram-negative bacteria. Alcohol-based hand antiseptics contain isopropanol, ethanol, n-propanol or a combination of two agents; they denature proteins and are effective against gram-positive and gram-negative bacteria, mycobacteria, fungi, enveloped viruses (HSV, HIV, influenza), hepatitis B (less susceptible) and hepatitis C. They are not effective against bacterial spores, protozoan cysts (for example, Acanthamoeba), certain non-enveloped viruses and CJD.  Preparations that use 4% chlorhexidine are most effective. Chlorhexidine has residual activity on the skin, but allergic reactions are uncommon. Infection rates have been reported as being lower after antiseptic hand-washing, using chlorhexidine, rather than after hand-washing with plain soap or alcohol-based hand rinse. Iodine and iodophors have good bactericidal activity but cause more irritant contact dermatitis. Quaternary ammonium compounds for example, benzalkonium chloride, are only bacteriostatic and fungistatic and are affected by organic material. Triclosan (found in antibacterial hand-wash for home use) is often only bacteriostatic and has poor activity against gram-negative bacteria. Alcohol-based hand rubs/gels are unsuitable for use in contact lens practice because the residual debris and bacterial toxins on the hands, and chemicals from the hand-rub, may be transferred to the lens prior to insertion in the patient’s eye.

Powder-free surgical gloves should be available for use in all practices. Gloves should be worn when there is a possibility of contamination with blood or body fluid (for example, where either the patient or the optometrist has open wounds), or when optometrists or their staff are in contact with high-risk patients (for example, those with serious communicable diseases, such as hepatitis B, active herpetic lesions). Optometrists should frequently check their hands for cuts or abrasions. Gloves do not replace hand-washing; hands should be washed before and after using gloves. Although broken skin may be detected through stinging when the hands are wiped with an alcohol swab, there is the possibility of contact dermatitis developing from alcohol swab use. Latex gloves are not suitable for all optometrists and patients because of reported latex allergy. Surgical masks should be used, if either the optometrist or the patient has a cold or influenza. Gloves are also recommended when contact with cleaning solutions such as glutaraldehyde or sodium hypochlorite.

Optometrists should consider being immunised against influenza yearly, hepatitis A (when seeing institutionalised patients, including nursing homes) and hepatitis B. In addition, optometrists should consider being immunised against measles/mumps/rubella.

DAILY HYGIENE REGIMEN OF WAITING ROOM AND OFFICES

There should be regular cleaning and disinfecting of all surfaces. The same goes for the bench surfaces, chairs and equipment. Clean bench tops with a regular household detergent and water.  Clean the sink with household detergent and water, then dry with a disposable towel.  Remove all visible soil and dirt from floors and walls (damp mopping is recommended where possible).  As computers and iPads in health-care settings may become contaminated with potentially harmful micro-organisms, wipe computer keyboards with a disinfecting cloth each day.

Infection control also includes regular and effective cleaning of all areas of the practice, using plastic liners in wastebaskets, proper disposal of waste, and vermin control within the office.

DAILY HYGIENE REGIMEN OF INSTRUMENTATION IN OPTOMETRIC PRACTICE

Put covers on equipment (for example, slit-lamp) when not in use. Where the patient comes into contact with examining equipment, wipe the counter surfaces and areas with isopropyl alcohol tissues, 30% alcohol solution, or sodium hypochlorite solution (a 1% solution can be obtained by a 1:5 dilution of 5% household bleach).

Single-use instruments and equipment should be used whenever possible in optometric practice, but there are several items in optometric practice that are reused. All reusable instruments need to be cleaned immediately and then disinfected or sterilised.  As applanation tonometer probes are the most common item in the consulting room to regularly come into contact with mucous membranes and tears of patients, optometrists must ensure that they are cleaned and maintained appropriately. They should be cleaned before and after use. Although alcohol swabs are commonly used to clean tonometer prisms, continuous soaking with alcohol have been reported to cause damage to tonometer prisms, such as surface scratching and dissolving of the glue holding the tonometer prism together. Instead use 3% hydrogen peroxide to clean tonometer prims, gonio lenses, and fundus lenses. A five-minute soak in 3% hydrogen peroxide is capable of removing the hepatitis B, hepatitis C virus, adenovirus, (a common cause of epidemic keratoconjunctivitis) and Acanthamoeba. Thereafter, rinse thoroughly with cold water, dry with tissue. Store in a clean, dry container.

External rims of diagnostic bottles (i.e., anaesthetic, mydriatic, fluress, and saline bottles) may become contaminated. Optometrists should ensure the bottle tip never touches the patient’s eyes or the optometrist’s hands, and the bottle cap should be replaced immediately after use. Ensure that the eye drop has not reached its expiration date. It is advisable to mark on the bottle the date it was opened. Refrigerate eye drops if appropriate. However, it is recommended that food is not kept in refrigerators where drugs are kept. The practice should have a well-equipped first aid kit. Infectious material must be disposed of as biohazardous waste. To avoid needle stick injury, needles should not be re-sheathed or removed from disposable syringes. ‘Sharps’ must be discarded in clearly labelled, puncture-proof containers. Collection of ‘sharps’ and potentially infectious waste can be organised through a collection service or arrangements made with a local general medical practitioner.

CONTACT LENS DISINFECTION

Contact lenses should be applied or removed only after proper hand washing. Ideally, trial hydrogel contact lenses should be used only once. If it is necessary to use diagnostic lenses on a number of patients, in practice disinfection procedures must be effective against bacteria, viruses (adenovirus, hepatitis, HIV), fungi and Acanthamoeba. Although there is a theoretical risk of transmission of HIV via trial contact lenses, there have been no reported cases. All trial contact lenses used in patients who are carriers of infectious diseases (for example, CJD, HSV, hepatitis, HIV or adenovirus), must be disposed of immediately. All diagnostic contact lenses should be cleaned and rinsed just prior to and immediately after use.

Clean hydrogel diagnostic contact lenses with a hydrogel lens cleaner via digital cleaning (20 seconds per side).  Rinse with sterile preserved saline. Fill glass vial with sterile saline.  Label with lens parameters and date of heating.  Sterilise in autoclave at 134 ⁰C, for at least three minutes or 121 ⁰C for at least 10 minutes.  Alternative: thermal disinfection unit 78 to 90 ⁰C for 20 to 60 minutes. Optometrists could consider asking a local dentist or general medical practitioner to autoclave contact lenses, if they do not want to purchase their own bench-top unit. Despite its efficacy, 3% hydrogen peroxide is not recommended, as contact lens parameter changes may occur with prolonged storage in peroxide. In addition, lenses cannot be stored for longer than 24 hours in the neutralised peroxide solution. Transfer to a new storage solution carries the risk of recontamination. Chemically preserved disinfectants are not suitable, as they have unknown efficacy against viruses and are questionable at limiting biofilm formation and fungal growth. Practitioners should take care to avoid cutting themselves when removing metal seals on contact lens containers.

Clean gas permeable contact lens with approved gas permeable (GP) cleaner via digital cleaning (20 seconds per side). Rinse with sterile preserved saline. Soak in 3% hydrogen peroxide for a minimum of three hours.  Rinse with sterile preserved saline. Dry GP lens with a clean tissue and store in a dry container. There is significantly less risk of contamination during dry storage compared to long-term storage in conditioning solutions.  GP lenses must be thoroughly surface cleaned and rinsed prior to reuse. GP lenses should not be heat disinfected because the lenses may warp. 

CLINICAL PEARLS

• Optometrists and optometric practice staff should adopt measures to minimise the risk of transmission of infection. These include appropriate hand-washing, staff vaccinations, single use instruments/equipment, appropriate disposal of waste, appropriate methods of reprocessing, where items are reused.
• Information provided to patients regarding infection control procedures in topical drug administration, contact lens wear and use of eye make-up are additional considerations for optometrists.
• Chlorhexidine-based hand-wash is commonly accepted as the most suitable hand hygiene product. When using an alcohol-based hand rub, the CDC recommends that the hands should be rubbed until dry, being careful to cover the entire skin surface of the hands and fingers.
• Fingernails should be of reasonable length and clean; wearing artificial nails is not recommended because they are a reservoir of gram-negative bacteria even after hand washing.
• Hands should be inspected frequently for cuts, abrasions, or breaks in the skin. Gloves are not a substitute for hand washing. Gloves are for single-use only and are discarded after each patient use. Hands should be washed after gloves are removed.
• Instruments that come in contact with the patient’s ocular surfaces, such as tonometers, gonioscopy lenses and fundus contact lenses, should be wiped clean and thoroughly disinfected and/or sterilised.
• Boiling is not an acceptable method for sterilising equipment, neither is the use of ultraviolet light. A small tabletop steam autoclave unit is the most efficient and cost-effective method of in-office sterilisation. Items requiring sterilisation should be properly prepared by wrapping in peel pouches before sterilisation to maintain instrument sterility after processing.
• Hydrogen peroxide is the only disinfection system approved by the CDC for the disinfection of HIV.

CONCLUSION

All optometrists are encouraged to actively adopt infection and sterilisation regimen to decrease the risk of transmitting an infection. Every office should have a protocol for common surfaces and instruments, as well as preventing patients and staff from acquiring an infection.

REFERENCES

1. Lakkis C, Lian KY, Napper G, Kiely PM. Infection control guidelines for optometrists 2007.Clin Exp Optom.2007 Nov;90(6):434-44.
2. Semes L. Infection control for ophthalmic patient-care items.Rev Optom Supp1997(The 1997 Clinical Guide to Ophthalmic drugs), 48A.
3. Cockburn DM, Lindsay RG. Infection control guidelines for optometric practice.Clin Exp Optom.1995 May;78(3): 110–2.