Coronavirus: How to disinfect optical equipment and premises

Guidance on cleaning surfaces and equipment following patient contact

optical equipment

We have received a number of questions over what is the best way to clean surfaces and equipment following patient contact. The first point is that before using any cleaning products you should be aware of what they contain and if they are suitable for the equipment in question.

The data on SARS-CoV-2, the virus that causes COVID-19 is still emerging and as with all information on this disease, is liable to change quickly and often.

What should I use for precautionary cleaning in optometric practice? 

There is a current lack of research into surface cleaning for SARS-CoV-2, however, there is some research on other coronaviruses.

Table 1: Antimicrobial agents

Ethanol
Concentration: 70%
Exposure time: One minute 
Virus reduction (%): >99.9

Sodium hypocholorite 
Concentration: 0.1%
Exposure time: One minute 
Virus reduction (%): >99.9

Sodium hypocholorite 
Concentration: 0.5%
Exposure time: One minute
Virus reduction (%): >99.9

Research shows1 that sodium hypochlorite 0.1% and a solution containing 70% ethanol were effective against other coronaviruses on small surfaces. For larger areas such as floors, 0.5% sodium hypochlorite is advised.

Similar results were obtained for common disinfectant/detergents containing sodium lauryl ether sulphate, alkyl polyglycosides or coco-fatty acid diethanolamide, although they may require a longer contact time (five minutes) to achieve the same results2.

Where can I find those chemicals?

Sodium hypochlorite is found in most household bleaches. Therefore, if the household bleach has a 5% concentration to begin with, a 1:50 dilution will give the required concentration of 0.1%. If you require a different concentration or the initial concentration varies you will need to adjust the ratio.

Note: Household bleach will be damaging to some surfaces, in those cases decontamination can be carried out with a household detergent followed by a solution containing at least 70% ethanol.

  • Sodium lauryl ether sulphate also known as sodium laureth sulphate is found in many soaps and cleaners
  • Alkyl polyglycosides are a class of surfactants also found in cleaning products
  • Coco-fatty acid diethanolamide also known as cocamide DEA, or cocamide diethanolamine is also found in soaps

Why do these products work on coronaviruses?

Soaps disrupt the outer lipid layer of the coronavirus, breaking them apart and then trapping any virus fragments allowing them to be rinsed away.

Ethanol and sodium hypochlorite can also both disrupt the outer layer and damage the protein structure.

How quickly do they work?

Sodium hypochlorite 0.1%, 0.5% and ethanol 70% were shown to reduce coronavirus activity by a significant amount after one-minute exposure time.

What should I do in practice?

First you need to check the manufacturer’s instructions to make sure the cleaning products won’t harm equipment or fixtures and fittings. As you may be using a bleach-based product you will need to consider the effect on the colour of anything cleaned. If in any doubt contact the manufacturer.

To be effective you need to:

  • Ensure that the cleaning agents contain ingredients proven to work on coronaviruses, and
  • Allow cleaning products sufficient contact time before being wiped away

Wherever possible use a disinfectant/detergent solution followed by either a sodium hypochlorite 0.1% solution or a 70% ethanol solution. However, in some instances that won’t be practical or possible:

  • The World Health Organisation (WHO) recommends 70% ethanol solutions are used to disinfect reusable equipment between patient uses as long as it is safe to do so. This would apply to headrests, chinrests, handles, trial frames and similar
  • For commonly touched surfaces the WHO recommends 0.5% sodium hypochlorite solution for healthcare facilities3
  • The European Centre for Disease Prevention and Control (ECDC) recommends a 0.1% sodium hypochlorite solution for non-healthcare settings4

Evidence suggests that 0.1% sodium hypochlorite solution is effective against other coronaviruses. Therefore, in our opinion, 0.1% sodium hypochlorite is sufficient for general cleaning purposes as practices should not be seeing patients with COVID-19.

Can I use antimicrobial wipes?

Yes, for wiping down equipment and frames (as long as they won’t damage them) but you must ensure they contain one of the active ingredients in sufficient quantities and that you can get sufficient contact time for the active ingredients to work.

Examples of antimicrobial wipes include:

  • Clinell wipes
  • AZO wipes with 70% IPA

Any other wipes with a 70% ethanol content should be equally suitable.

What about soft surfaces such as chairs? 

Soft surfaces are far more difficult to clean effectively and are more likely to be damaged by bleach-based cleaners. Our view is that for now any soft surfaces should be replaced with hard surfaces to aid cleaning. If they cannot be replaced, consider if they can be removed from patient areas in the short term.

Do I need to wear PPE?

Yes, you should wear PPE especially if conducting a deep clean. That means a suitable facemask (Type IIR), gloves, apron and eye protection. Facemasks and goggles (if worn) are sessional items and may be left on as long as they are not contaminated. Remember, gloves and aprons must be changed between patients.

Watch our video - COVID-19: Premises and equipment disinfection guide

References

1 G. Kampf et al. / Journal of Hospital Infection 104 (2020) 246e251
2 MY Lai et al. Clin Infect Dis. 2005 Oct 1;41(7):e67-71. Epub 2005 Aug 22
3 Q&A on infection prevention and control for health care workers caring for patients with suspected or confirmed 2019-nCoV  (accessed 20th April 2020)
4 ECDC TECHNICAL REPORT Interim guidance for environmental cleaning in non-healthcare facilities exposed to SARS-CoV-2 February 2020