The Covid- 19 Pandemy has brought several challenges to the health care systems throughout the planet since it requires complex strategies and public policies of contention, diagnosis, and treatment.
Especiﬁcally, the high transmissibility of the virus is a critical point of the pandemic, which turns the medical teams highly vulnerable.
However, the role of the eyes and tears both as entry routes for the causative virus, SARS-CoV-2, and as sources of contagion is still the subject of debate, and relatively less is known about the ophthalmic implications of the disease.
It would appear from some recent studies that patients who experience the more severe forms of COVID-19 and present with pneumonia commonly display ocular symptoms.
However, the authors of a recent Chinese study of 40 patients concluded that although a third of patients with the disease had ocular abnormalities, there was a low prevalence of the virus in tears.
Nevertheless, it is possible that contact with infected eyes could be a route of transmission of SARS-CoV-2, especially given the knowledge that it can be spread via direct or indirect contact with other mucous membranes (the mouth and nose), so ophthalmologists should err on the side of caution and ensure rigorous prevention protocols are put in place.
In a literature review recently published in Ophthalmology and Therapy, Prof. Jorge Alió and Dr. Alejandra Amesty reported that when it occurred, conjunctivitis was the most common ophthalmologic sign related to coronavirus infection.
And there are clues from previous coronavirus outbreaks as to why this should be the case: inflammation of the conjunctiva was first associated with a human coronavirus back in 2004 when children started to fall prey to the symptoms during the severe acute respiratory syndrome (SARS) crisis.
Genetically speaking, SARS-CoV-2, the virus that caused SARS, is around 70% similar to SARS-CoV and uses the same receptor (ACE2) to insert itself into human cells. This is potentially quite significant when one considers that ACE2 receptors have been found in the aqueous humor.
But could the fact that conjunctivitis is mainly being seen in the most poorly patients mean that the presence of the virus on the surface of the eye and subsequent ocular events are down to decreased immune function?
The researchers do not think so: “Both viral diseases and immune problems can lead to ocular manifestations, such as conjunctivitis, uveitis, and retinitis, among others. It is difficult to determine the pathology of ophthalmic involvement.”
However, since the virus has been cultured from conjunctival secretions, COVID-19 ophthalmopathy is more likely to be related to the actual virus infestation rather than the secondary immune reaction that the infection may cause.
Any sign of conjunctivitis in the clinical setting should be considered to be a “possible coronavirus conjunctivitis, especially when accompanied by other respiratory tract problems or fever”, the authors pointed out.
Thankfully, viral conjunctivitis usually amounts to no more than an uncomfortable nuisance, so treatment strategies are typically supportive in nature. That said, it is important to try to lessen the potential viral load on the ocular surface and some of the general ophthalmic recommendations for viral conjunctivitis could also apply to COVID-19 patients.
“These include hygienic measures (frequent hand washing, especially when eye drops need to be applied or contact lenses worn; avoiding touching or rubbing the eyes; changing pillowcases, sheets) … we should be meticulous when examining patients who have tested positive for COVID-19.”
The close face-to-face proximity of ophthalmologists to their patients and frequent exposure to tears and ocular discharge, as well as regular handling of equipment such as slit lamps, tonometers, and lasers, means they are perhaps at a higher risk of contracting COVID-19 than other types of healthcare professionals, the researchers said, referring to recent guidelines that have been published in an attempt to minimize the chances of infection spreading in ophthalmology clinics and hospital departments.
In the guidance, ophthalmologists are advised to impose limits on the number of attending patients and to adhere to strict appointment timetables to prevent people from gathering in clinic waiting rooms.
Online platforms, such as hospitals’ official websites, should be readily used, whilst simply making more telephone calls could reduce the need for patients to visit hospitals, for example, by helping them to distinguish between urgent and nonurgent ocular problems.
The guidelines go on to recommend triage systems to help to flag up patients with symptoms consistent with COVID-19 infection such as fever, and online ordering and delivery of prescribed medication, especially for chronic eye diseases such as glaucoma.
Also, slit lamps should be protected by shields and direct ophthalmoscope examination could be replaced by slit light lenses, optical coherence tomography, or fundus photography. For inpatients, the suggested adaptations include preoperative infection screening and the use of local rather than general anesthesia to avoid contamination.
Negative-pressure operating rooms should be used for emergency operations on any COVID-19-positive patients.
Human coronavirus is believed to be able to remain infectious on inanimate surfaces for as many as 9 days, so disinfecting surfaces with water, detergent, and commonly used disinfectants is extremely important.
Also, they suggested that some ocular spray disinfectants that contain hypochlorous acid (usually applied to treat blepharitis to reduce the bacterial and viral load on the skin and eyelashes) could be used as “a measurement of prevention for the facial area where many other chemical agents cannot be applied”.
However, more studies are needed to establish a specific antiviral product that could be used to reduce the viral load on infected patients’ conjunctiva and lower the transmission rate via the eyes/tears.
The authors conceded that this is no easy task when “so many doubts remain regarding the ophthalmic implications” of the infection.
More research Summarising, the authors have called for “well-designed trials” to be conducted “to rule out other ocular manifestations [besides conjunctivitis] that may result from COVID-19 infection and to better elucidate the mechanisms of transmission through the eyes.”
Until more light can be shed on the ophthalmic implications of COVID19, ophthalmologists can only remain as up-to-date as possible on emerging disease findings, whilst maintaining a cautious approach when dealing with patients before, during, and after appointments.