Caused by the SARS-CoV-2 virus, COVID-19 is a global health crisis which has rapidly spread around the world. As of the time of writing, there have been 87,753,382 cases worldwide with 21,481,788 cases in the US per the data from Johns Hopkins University
This virus emerged in Wuhan, China and the first doctor to recognize it was Dr. Li Wenliang, an ophthalmologist, who alerted his colleagues when he encountered multiple cases of pneumonia resembling severe acute respiratory syndrome (SARS) in his hospital.1 Unfortunately, Dr. Li later contracted this virus from an infected but asymptomatic glaucoma patient and passed away from the disease on February 7th, 2020.
“Infectious diseases often present with ocular symptoms, and eyecare professionals must be prepared to recognize these signs when they present in our chair.”
As the pandemic continues throughout the world, we will get patients who have recovered from this disease in our chair and it is important for us to recognize how this virus has impacted their eyes. Not only that, but we must also be prepared to recognize any signs of the virus in currently infected asymptomatic patients, both to protect ourselves from getting the virus as well as warning these patients. Let’s look at all the places in our eyes where this virus is showing its effect.
This is the most well-known ocular symptom of COVID-19. There are multiple reports of conjunctival congestion and conjunctivitis being the first symptom in patients infected with SARS-CoV-2, and even the ocular secretions of these patients contained the virus.1 These patients with conjunctivitis could present to clinic with headache, fever, chills or cough which could be a warning sign for the doctor. Thus, eye care professionals may be the first in line to assess and alert the patient potentially infected with the virus.
If the virus is present in the ocular secretions that means it can also be transmitted via the ocular surface as well. There are reports on transmission by aerosol contact with conjunctiva if there is no eye protection being worn.2 Thus optometrists and ophthalmologists may be the first health care providers encountering a possible COVID-19 positive patient.1 Due to the proximity between the patient and the doctor during slit-lamp examination, this can pose a direct risk of transmission to the doctor. It is highly recommended for these doctors to have some form of eye protection (face shield or safety goggles) in addition to N95 mask to reduce the chances of transconjunctival aerosol infection.
Coronavirus in cornea
We know that the conjunctival tissue and its secretions contain coronavirus in positive patients, but does this virus penetrate further into the ocular surface or through the cornea?
One study looked at the prevalence of SARS-CoV-2 virus in human post-mortem ocular tissues and it showed a small but noteworthy prevalence of SARS-CoV-2 in ocular tissues from COVID-19 donors.3 In the study, ten COVID-19 positive donor ocular tissues were assessed and out of them three conjunctival, one anterior corneal, five posterior corneal, and three vitreous swabs tested positive for SARS-CoV-2 RNA.3 The study did not show if the transfer of infection was possible during corneal transplant with tissue from an infected donor.
Even though the prevalence in ocular tissues is small, it does raise questions about the route of transmission of the virus through ocular tissues. The primary route of SARS-CoV-2 infiltration is known to be through the respiratory droplets but a non-respiratory route of transmission still could not be ignored.3 It was not clear if the virus RNA got there due to initial ocular infection or retrograde transfer from nasolacrimal duct.3 The study is again reminding us about the necessity of our eye protection during eye exams.
The effect on retina
Due to the novelty of the virus, very few studies have yet looked at the retinal complications caused by this disease. Many of the patients who recovered from the condition have started going to their eye doctor for their regular exams, and retinal complications or OCT changes have started to appear in these patients.
A recent study looked into the retinal findings in hospitalized patients. Dilated fundus exam was performed on patients hospitalized due to COVID-19 and retinal vascular lesions, such as flame-shaped hemorrhages and cotton wool spots, were the main findings. One patient had retinal sectorial pallor suggestive of recent retina ischemia.4 The study was first of its kind, making direct correlation between tissue damage due to SARS-CoV-2 or thrombotic complications difficult to distinguish.4
A second study further examined the OCT angiography of patients who have recovered from COVID-19. The course of COVID-19 was mild in these patients and very few of them required hospitalization. In the study, vessel density (VD) of the superficial (SCP) and deep retinal capillary plexus (DCP) and the area of the foveal avascular zone (FAZ) were measured in COVID-19 recovered patients versus age-matched controls.5 The VD in SCP and DCP were significantly reduced in foveal and parafoveal regions and FAZ was also greater but not significantly in these patients.5 These patients may be at risk of retinal vascular complications.5
The effects of COVID-19 on the retina may still require further research, but the closures and lockdown due to the pandemic have changed the characteristics of retinal detachments at first presentation. There is a report of a significant increase in the number of RDs presenting with macular detachment, poor baseline VA and larger areas of detached retina between May and September 2020.6 The reasons noted include patients avoiding going to ER due to fear of COVID-19, as many were not sure if eye clinics were open or not and some could not understand the urgency of their symptoms.6 Patient education regarding the signs and symptoms of retinal detachment at their initial visit for a general eye exam could help save their vision in the future.
Neuro-ophthalmological manifestations of COVID-19
Neuroinvasive and neurotrophic capabilities of coronavirus have also been proposed but their pathways are not well understood. These studies have reported CNS involvement of the virus leading to acute encephalitis-like syndrome, acute disseminated encephalomyelitis, and multiple sclerosis.7 These reports on neurological manifestations of COVID-19 have been increasing on daily basis and include dizziness, headache, seizures, changes in mental status, ataxia, acute cerebrovascular disease, CNS vasculitis, posterior reversible encephalopathy syndrome, acute necrotizing myelitis, encephalitis, and impairment of taste and smell.7
Headache was the major symptom of the virus, whereas diplopia and ophthalmoparesis were also noted in two cases. There was also another case of facial nerve palsy with an unresponsive blink reflex.7 Lastly, optic neuritis was also noted with an animal coronavirus model but no data in the human model.7 The research presented a wide variety of neurological manifestations of the coronavirus, but the study had some limitations. Ocular and neurological examination in COVID-19-positive patients were hindered due to safety concerns, limiting a better understanding of any association.7
This article proves that eyecare professionals are first in line to encounter a positive patient as well as being the first to see the symptoms of coronavirus and alert the patient. This warrants us to have the best personal protective equipment to protect ourselves, our staff, and other patients. Eye care clinics should screen for fever and a COVID questionnaire at the point-of-entry and on phone call prior to booking an appointment. Patients with red eye should be screened and assessed in a separate room with staff and doctor geared in full personal protective equipment.2
Most of the studies about the association of coronavirus to ocular health are the first of their kind and are presenting initial data. All of these studies had similar limitations such as small sample sizes, lack of data, and other confounding factors such as comorbidities which could have skewed any results. These limitations will tend to improve as further studies are done with increasing cases throughout the world but also increasing recoveries. As more data and studies are presented, eye care professionals will also have a better understanding of assessing the eyes of patients post COVID-19 recovery.
CovalentCareers is committed to supporting optometrists and optometry students during the Coronavirus pandemic. For more optometry-specific resources and information, visit our Optometry COVID-19 Resource Center.
- Bacherini, D., Biagini, I., Lenzetti, C., Virgili, G., Rizzo, S., & Giansanti, F. (2020). The COVID-19 pandemic from an ophthalmologist’s perspective. Trends in Molecular Medicine.
- Khanna, R. C., & Honavar, S. G. (2020). All eyes on Coronavirus—What do we need to know as ophthalmologists. Indian journal of ophthalmology, 68(4), 549.
- Sawant, O. B., Singh, S., Wright III, R. E., Jones, K. M., Titus, M. S., Dennis, E., ... & Mian, S. I. (2020). Prevalence of SARS-CoV-2 in human post-mortem ocular tissues. The Ocular Surface.
- Pereira, L. A., Soares, L. C. M., Nascimento, P. A., Cirillo, L. R. N., Sakuma, H. T., da Veiga, G. L., ... & Abucham-Neto, J. Z. (2020). Retinal findings in hospitalized patients with severe COVID-19. British Journal of Ophthalmology.
- Abrishami, M., Emamverdian, Z., Shoeibi, N., Omidtabrizi, A., Daneshvar, R., Rezvani, T. S., ... & Sarraf, D. (2020). Optical coherence tomography angiography analysis of the retina in patients recovered from COVID-19: a case-control study. Canadian Journal of Ophthalmology.
- Arjmand, P., Murtaza, F., Eshtiaghi, A., Popovic, M. M., Kertes, P. J., & Eng, K. T. (2020). The Impact of the COVID-19 Pandemic on the Characteristics of Retinal Detachments: the Canadian Experience: Characteristics of Retinal Detachments during COVID-19. Canadian Journal of Ophthalmology.
- Luís, M. E., Hipólito-Fernandes, D., Mota, C., Maleita, D., Xavier, C., Maio, T., ... & Ferreira, J. T. (2020). A Review of Neuro-Ophthalmological Manifestations of Human Coronavirus Infection. Eye and brain, 12, 129.