Coronavirus disease 2019 (COVID-19) is caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). SARS-CoV-2 belongs to the group IV Coronavirinae in the subfamily Orthocoronavirinae, order Nidovirales, with four genera: alphacoronavirus, betacoronavirus, gammacoronavirus, and deltacoronavirus (not to be confused with the variants of SARS-CoV-2, which have similar names). Members of the alpha and beta genera can cause infections in humans. Seven strains have been isolated from human infections: 229E (α), NL63 (α), OC43 (β), HKU1 (β), MERS-CoV (β), SARS-CoV (β),¹ and SARS-CoV-2 (β). Strains 229E, NL63, HKU1, and OC43 cause mild-to-moderate respiratory infections and represent one-third of common colds; MERS-CoV, SARS-CoV, and SARS-CoV-2 infection can lead to death.^1,2

SARS-CoV-2 is a member of the sarbecovirus subgenera of the betacoronavirus. SARS-CoV-2 most likely evolved from bat coronaviruses, as its genetic sequence is closely aligned with those from bats (88% to 96% identify), but it has only 80% similarity with SARS-CoV and 50% similarity with MERS-CoV.³ The divergence of SARS-CoV-2 and the bat sarbecovirus reservoir is estimated to have occurred between 1948 and 1982,⁴ indicating that SARS-CoV-2 has been circulating unnoticed in bats for several decades. All human coronaviruses are believed to have evolved in bats or rodents and may be directly transmitted from these to humans or through intermediate animal hosts, such as camels for MERS-CoV.⁵

EVOLUTION OF SARS-COV-2: PRODUCTION OF VARIANTS

While the interaction of the SARS-CoV-2 spike protein with angiotensin-converting enzyme-2 (ACE2) initiates the infection process, it is the replication of the viral genome that gives rise to SARS-CoV-2 variants. All coronaviruses carry their genetic code as positive-sense, single-stranded ribonucleic acid (RNA). “Positive-sense” means that the RNA is similar to our messenger RNA and can be directly translated into proteins. This means that positive-strand RNA viruses need to encode an RNA-dependent RNA polymerase to produce a negative-sense copy of their genome, which is then transcribed into their positive-sense RNA.

Coronavirus genetic diversity is facilitated by: 1) their large genomes, giving a greater likelihood for mutations; 2) infidelity of RNA-polymerase, leading to substitution of nucleotides in the RNA code; and 3) a high recombination frequency, meaning that cells infected by two different coronaviruses can exchange their RNA to produce genetically distinct progeny. Mutations that allow faster replication, better transmission, and/or evasion of immune systems are selected.

The variants that we are currently familiar with—alpha, beta, gamma, delta, and omicron—all have genetic changes. The most reported changes are those that occur in the spike protein, which confers changes to interactions with ACE2. The delta variant has nine genetic variations, resulting in amino acid substitutions, including L452R, T478K, D614G, and P681R, in the spike protein. These designations refer to the position of the amino acid in the protein’s sequence and to the amino acid changes. Thus, L452R indicates a change from leucine (L) to arginine (R) at position 452, and so on.

Omicron, on the other hand, has 34 changes to its spike protein⁶ as well as changes to other proteins such as its envelope, membrane, and nucleocapsid proteins. Presumably, these changes occurred because of selection pressures exerted on the virus; some may simply have occurred randomly. The mutation N501Y increases the spike protein’s binding to ACE2 receptors, and its combination with Q498R may increase the binding affinity. The changes H655Y, N679K, and P681H may increase the cleavage of the spike protein, an important step for fusion of the viral membrane with the host cell membrane.

COVID-19 AND THE EYE

Because this topic is so extensive, we discuss only a few studies in this section. For a more in-depth analysis, readers may refer to the papers referenced as well as to reviews specifically covering this topic.^7,8

Ocular complications, usually conjunctivitis, may be the first symptom of COVID-19 in fewer than 2% of cases.^9-11 Only 2% to 11% of patients who have confirmed or suspected COVID-19 show at least one ocular symptom.^12-14 The most common ocular complications, in order of most common to least common, include redness, dry eye or foreign body sensation, tearing, itching, discharge, vision impairment, and eye pain.^12,15 Ocular complications post-vaccination, while rare, have included optic neuritis, diplopia, and cranial nerve palsies.^16,17 These data tend to suggest that ocular manifestations occur after the initial stages of the disease and when the disease is worsening.

An interesting study demonstrated the efficacy of a 1% povidone iodine (PVP-I) mouthwash/gargle, nasal drop, or eye drop administered to COVID-19 patients. The patients receiving the 1% PVP-I had reduced mortality, morbidity, hospitalization, and financial burden.¹⁸

There have been reports of ocular mucormycosis during COVID-19.^19,20 This rare fungal infection is caused by a group of molds called mucormycetes (Figure 1). To the best of our knowledge, there is no evidence that contact lens wear is associated with this disease. The disease during COVID-19 most likely results from patients being prescribed corticosteroids to reduce inflammation.

IS THE END IN SIGHT?

No, but we are in a better place than we were one year ago; and, hopefully, we will be in an even better place in another year.

Our hope is that SARS-CoV-2 will mutate to produce variants that cause only mild disease and do not result in long COVID. Certainly, SARS-CoV-2 will mutate, it is mutating now, to produce new variants. Hopefully, none are of greater pathogenicity.

In the meantime, we need to protect the whole world. Some countries have excellent vaccination rates. The United Arab Emirates, Brunei, and Portugal were ≥ 90% double-vaccinated in January 2021. However, many countries, such as Burundi, Democratic Republic of Congo, Haiti, and Chad, are struggling to achieve first-dose vaccination rates above 1%.²¹

We have effective vaccines and can produce new vaccines as needed. Studies examining transmission of the delta variant within vaccinated and unvaccinated individuals in the United Kingdom concluded that vaccination reduces transmission.^22,23 As of this writing, we have no peer-reviewed data about the efficacy of vaccines against the omicron variant; however, Pfizer-BioNTech is reporting that laboratory studies demonstrate that three doses provide protection.²⁴

HAVE OTHER MEASURES BEEN EFFECTIVE?

Mask wearing, social distancing, and other measures have had significant impacts on the spread of COVID-19 and of other diseases such as influenza, with Australia’s influenza cases at an all-time low.²⁵

Recommendations for ophthalmic healthcare practitioners to consider during the COVID-19 pandemic have included:

• Triaging patients before visits.
• Frequent hand washing.
• Frequently disinfecting surfaces.
• Social distancing when possible.
• Refraining from speaking during examinations.
• Using a protective shield on slit lamps.
• Disinfecting contact lenses, equipment, and trial sets with water and detergent, and frequently applying commonly used hospital-level disinfectants such as sodium hypochlorite, 70% alcohol, or 3% hydrogen peroxide.
• Using appropriate personal protective equipment (PPE).
• Minimizing the time of direct contact with patients.
• Performing only absolutely necessary procedures.
• Not attending work if feeling unwell.
• Using telehealth with patients.^26-30

Practitioners also may want to evaluate whether they need to be vaccinated (many countries are now requiring this) and whether they should require their patients to be vaccinated to help reduce the likelihood of disease transmission. In some countries, such as New Zealand, optometrists are administering vaccines.³¹

Surveys have assessed whether these recommendations have been implemented and what other measures practitioners are using. A survey of contact lens practitioners in Germany, Austria, and Switzerland reported that respondents expected to be wearing face masks (55% to 70%, depending on the tasks involved) and to be disinfecting hands (in addition to normal hand washing, approximately 90%), and they expected patients to take similar measures.³² A survey from Israel reported that experienced practitioners were less likely to see patients during a COVID-19 wave or between waves.³³ The most common PPE or hygiene procedures were wearing face masks (81% to 99% of respondents), hand washing (99.8%), and cleaning surfaces (93%); furthermore, after successive waves, more people used full face shields (6% to 32%) and slit lamp-protecting dividers (8% to 56%).^33,34

THE EFFECT OF COVID-19 ON CONTACT LENS WEAR

A study examining the advice that contact lens educators would give to future practitioners indicated that respondents (globally) expected students to use face masks, gloves, and eye shields (90%); sanitize hands (86%); disinfect contact lens equipment and trial sets (83%); use protective shields on equipment (81%); practice social distancing (81%); and reduce patient contact (65%).³⁵ The majority of respondents would advise students to pay more attention to hand hygiene and to lens care procedures (93%), keep unwashed hands away from faces (76%), recommend daily disposable rather than reusable lenses (63%), and recommend cessation of contact lens wear when unwell (57%). Only 18% of respondents expected to advise students to recommend spectacles rather than contact lenses.³⁵

Recommendations for contact lens wearers during the pandemic have included the following:

• Wash hands using soap and water, and dry hands with a disposable paper towel before applying or removing lenses.
• Disinfect the lens package and hands with 70% ethyl alcohol or another antiviral disinfectant.
• Maintain good contact lens hygiene.
• Avoid touching or rubbing eyes.
• Cease contact lens wear immediately if there are changes to the eyes, and be seen by a qualified eyecare practitioner as soon as possible.
• Consider changing to daily disposable contact lenses if they are available and appropriate (even though no studies have reported that this is a safer lens wear modality).^28,30,36-39

The Centers for Disease Control and Prevention (CDC) has recommended the use of hydrogen peroxide-based systems as contact lens disinfecting solutions.⁴⁰ A recent paper has reported that unless a rub-and-rinse step is incorporated into lens hygiene procedures, several multipurpose disinfecting solutions do not reduce the ability of a coronavirus surrogate of SARS-CoV-2 to infect cells; however, hydrogen peroxide or povidone-iodine solutions are effective and reduced the infective titer to below detectable limits.⁴¹

Another recommendation has been to cease contact lens use altogether³⁹ except for cases in which other measures cannot be applied as a means of vision correction.³⁸ Nevertheless, no reports have shown that contact lens wearers are at increased risk of infection with SARS-CoV-2.^39,42 Despite the lack of evidence, there have been claims that contact lens wear is risky during the COVID-19 pandemic.^36,42,43 Again, with no evidence, others have stated that contact lens wear is not associated with COVID-19 risk.^44,45 Yet others have hypothesized but not shown evidence that contact lens wear may protect the eyes from infection by SARS-CoV-2 by acting as a sink to bind SARS-CoV-2 before it can bind to the ocular surface.⁴⁶ The only data that we could find on COVID-19 and contact lens wear was a study examining hospital inpatients (having significantly higher comorbidities) and outpatients that showed no difference in rates of contact lens wear (0.26% versus 0.28%, P = 0.838).⁴⁷

Contact lens wear does appear to have decreased during the pandemic, but fear of infection from COVID-19 usually accounted for only a small proportion (4% to 28%) of people reducing or ceasing lens wear.^48-51 In one questionnaire, 41% to 45% of respondents disagreed or strongly disagreed with the statement “contact lens use increases the danger of infection,” while 17% to 20% strongly agreed or agreed.⁵⁰ Similarly, 82% of people polled for another study did not believe that their risk of contracting COVID-19 would increase with contact lens wear.⁵²

A survey of optometrists from Mexico reported that 63% had decreased the frequency of fitting and/or refitting contact lenses; 58% also noted a decrease in sales of contact lenses.⁵³ In India, the lockdowns led to > 90% reduction in face-to-face consultations^54,55 and to a consequent increase in use of telemedicine.^56,57 Anecdotal evidence from India indicates a 30%-to-50% drop in contact lens sales.

Surveys/questionnaires conducted in the United Kingdom, Ireland, Spain, Portugal, Jordan, China, Australia, Saudi Arabia, and online have also shown that people are wearing contact lenses less during the pandemic.^48-52,58,63 The most common explanation was that contact lenses were less needed when spending more time at home.^48-51,59 One study examining the effect of face mask wear during contact lens wear found an increase in the number of people wearing contact lenses either sporadically or only two-to-three times per week, but this was related to spending more time at home, with only 16% relating this change to wearing face masks.⁴⁸ Most people reported that symptoms of discomfort in contact lenses did not change when wearing masks.⁴⁸

Some studies have examined the frequency of contact with eyecare professionals (optometrists and ophthalmologists) during the pandemic. In Jordan, 73% of respondents reported that they had contacted their eyecare practitioners less frequently during the pandemic.⁵¹ In addition, internet purchases of contact lenses increased from 6% before the pandemic to 12% during the pandemic.⁵¹ In one Spanish study, 88% of respondents indicated that no eyecare professional had offered them information related to contact lens wear and COVID-19, and 82% reported that they had not sought it on their own, highlighting that a lack of information could expose patients to higher avoidable risks during contact lens wear.⁵⁹ In another Spanish study, however, 54% of respondents received specific instructions, mostly about hand washing (93%) and storage case hygiene (49%).⁶⁰

Several studies have shown that contact lens wearers are often not heeding the advice for safety during lens wear. While several studies have reported that contact lens wearers are washing their hands more frequently during the pandemic,^51,52,58,59 inadequate hand washing continues to be the most frequent noncompliant behavior (36%).⁶⁰ Other studies reported that 48% of respondents used a shared towel to dry hands, and only 10% to 12% used a disposable paper towel.^58,61

While 57% of people still wearing contact lenses during the pandemic continued to rub and rinse their lenses as frequently as before the pandemic, 30% to 54% of respondents never rubbed their lenses before soaking, 42% never rinsed their lenses, 24% to 26% showered while wearing lenses, and only 10% reinforced this hygiene procedure.^58,59,61 Between 54% and 84% of contact lens wearers said that they would stop wearing lenses during the pandemic if they became infected or were unwell.^58,59,61

Between 18% and 67% of contact lens wearers were topping off lens care solutions in their lens cases frequently or occasionally.^58,61 Most people (82% to 86%) did not clean lens cases regularly and replaced lens cases less frequently than monthly (47% to 51%); 19% to 46% used tap water to rinse their cases.^58,61 However, a study from Jordan reported that 50% of contact lens wearers reinforced the habit of disinfecting their contact lens case during the COVID-19 pandemic.⁵¹

CONCLUSION

We will likely be living with SARS-CoV-2 for many years. Infections may wane, and the situation may not be classified as a pandemic if vaccination and other preventative measures continue to work and be used, or the virus may mutate to produce only mild disease. Many of the measures put in place during the SARS-CoV-2 pandemic have reinforced the role of hygiene in eyecare practice as well as hygiene practices of contact lens wearers. This may mean that they will be adopted for the longer term. We shall see. CLS

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