Two years of SARS-CoV-2 pandemic

Hygiene recommendations for optometrists and contact lens specialists have existed for decades. The need for hygienic measures for the optometric examination and education of patients and their handling of contact lenses becomes much more relevant during the Corona pandemic. Already after the outbreak of SARS-CoV, mainly in the Asian region in 2003, numerous studies were conducted and working methods developed to protect ophthalmic personnel.¹ They apply to their relevant fields of activity as well as to the specific premises used. Since the emergence of SARS-CoV-2 in Germany, specific hygiene recommendations and government-mandated guidelines have emerged, which change from time to time and are adapted to the prevailing conditions.

The feasibility of optometric examination and contact lens care during the pandemic is ensured by appropriate hygienic measures and infection control. Protective measures reduce the likelihood of infection and the spread of the coronavirus.

Viruses such as hepatitis C, among others, use the conjunctiva as a portal of entry into the body by binding to the cells of the ocular surface to cause infection.² SARS-CoV-2 does not follow this pattern.³

SARS-CoV-2 requires the membrane-bound enzyme ACE2 as a receptor and the serine protease TMPRSS2 as a binding site in order to infect a human cell and replicate.⁴ SARS-CoV-2 itself has a viral envelope with an outwardly projecting protein structure called a spike protein (S-glycoprotein). The spike protein attaches to the enzyme ACE2, which activates the serine protease TMPRSS2 and results in membrane fusion and release of the viral RNA in the host cell. This process is called endocytosis.

Expression of ACE2 receptors and TMPRSS2 can be detected in the epithelia of corneal and conjunctival epithelial cells, but occurs only at low levels. The conjunctival-mediated route of infection can therefore still not be ruled out.⁴

COVID-19 patients with ocular involvement have tested positive for coronavirus particles in the tear film in a few cases. However, this is no proof of the presence of infectious virus particles.⁵ Whether healthy people can become infected via the tear film was not clarified. However, any upper respiratory tract infection can lead to viral conjunctivitis as a secondary complication, including COVID-19.⁶ Triggers may include contact with aerosols or hand-eye contact. Therefore, the WHO and the American Academy of Ophthalmology (AAO) recommend that eye protection (e.g. goggles or shields) be worn during ophthalmic treatment of patients with suspected COVID-19 to prevent droplet infection.⁷ Optometrists, opticians and contact lens specialists should always proceed as usual in this regard and identify the cause of any conjunctivitis or corneal inflammation the patient presents with. Viral conjunctivitis, like K. epidemica (KCE), can be highly contagious and should always be referred to the ophthalmologist for further treatment.

Initially, classical droplet infection was considered the main route of transmission for SARS-CoV-2. After successful interdisciplinary, international research work, it is now known that transmission occurs mainly through very small airborne particles (aerosols) emitted by an infected person. Aerosols are emitted every time a person speaks, sings, sneezes, coughs, etc. and float in the air for different lengths of time depending on their size. At direct contact, less than 1.5 metres away, exposure to large droplets and aerosol is higher and decreases as the distance increases.⁸ Most respiratory droplets concentrate within 0.5 metres of a person's mouth before either becoming aerosols or falling to the ground.⁹ Providing as much fresh air as possible by regularly opening windows and doors or by using a room air conditioning system ensures a dilution effect of the virus load that may be present per cubic metre of air through targeted air exchange.

From the findings so far, the importance of an existing distance regulation indoors and outdoors of 1.5 metres between individual persons as well as the reduction of aerosols indoors by wearing a mouth-nose mask and by consistent ventilation and the proper use of ventilation technology can be justified. With increasing contact time and less distance to others, the risk of infection is more likely to occur.

The risk of contracting the multi-organ disease Covid-19 increases for each individual with the mutation of the SARS-CoV-2 variants Delta as well as the newly discovered variant Omicron in November 2021. Not proven for Omicron at this time (2 December 2021), but true for Delta, the variant is far more infectious than the SARS-CoV-2 virus that first appeared in Wuhan. Ocular involvement mainly manifests as conjunctivitis. In the cases detected, the conjunctivitis was mostly mild and follicular and could not be distinguished from other viral conjunctivitis.¹⁰ The causality between conjunctivitis and SARS-CoV-2 remains unclear and cannot be clearly determined.

This makes hygiene in one's own company and the implementation of the applicable country-specific regulations all the more important. Due to the many different operational situations in optometry, individual hygiene plans are necessary in order to maintain the protection of patients as well as to ensure the safety of the staff. Despite the reduction in the number of infections during the summer in Germany, the hygiene concepts that have been drawn up as well as individual, respective regulations in the federal states must be fully decided and consistently implemented. By September 2020, more than 24 million people had been proven to be infected with the SARS-CoV-2 coronavirus; in the meantime, around 263 million people have fallen ill and 5.22 million people have died worldwide.

The need for hygienic measures for the examination and education of patients and their handling of contact lenses remains highly relevant.

Fitting of contact lenses is and will remain a matter of discretion in some cases where it is unclear whether the prescribed hygienic recommendations are/can be followed by the patient. Contact lens wear is equally safe during the corona pandemic, provided that all hygiene rules of normal contact lens wear are continuously applied.¹¹

Contact lens hygiene should be supplemented by additional hand hygiene after putting on and taking off contact lenses. Hand washing after putting on and taking them off is for the protection of others. In accordance with guidelines for other types of disease, contact lens wear should be discontinued during illness.¹² The following hygiene rules should be communicated to the patient at each visit with increased urgency:

• Contact lens wearers must strictly comply with the manufacturers recommended wearing times.
• Reusable contact lenses must always be disinfected after each use. This requires thorough and extensive cleaning of the contact lenses. In any case, the contact lenses should be rubbed manually from both sides (at least 30 seconds) in the care product.
• The contact lens care solution must be used according to the manufacturer's recommendations.
• Contact lens care products must be resealed after use.
• In the case of COVID-19 disease, the previously used contact lenses and the opened care product must not be reused. The used contact lens case and other aids, such as tweezers, must be disposed as well or, if the material permits, sterilised.
• Contact lens wearers are advised to wear glasses during an illness to avoid infection of the conjunctiva.
• After full recovery, a new pair of contact lenses, an unopened lens solution and a new, unused lens case should be taken.

In managing COVID-19, most people are aware - but no one should tire of continuing to observe and follow the rules to limit the spread of SARS-CoV-2 as much as possible. For optometric practice, it is crucial that patients accept changes in their usual routine more than ever. They are not only confronted with this at the optician.

The general acceptance of hand hygiene is currently strong and this opens up the opportunity to increase compliance among contact lens wearers. Optometrists as well as contact lens specialists must be a trustworthy contact partner especially during this time.

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