eye

Coronavirus Disease (COVID 19) and Eye

  • blog
  • 26th May, 2021
eye

INTRODUCTION

Coronavirus Disease 19 (COVID 19), is caused by the highly transmissible Severe Acute Respiratory Syndrome Corona Virus type 2(SARS-CoV-2) previously named as novel coronavirus 2019. It is a single-stranded, positive-sense, enveloped RNA Virus. Coronaviruses are separated into 4 types. Alpha coronavirus, Beta coronavirus, Gamma coronavirus and Delta coronavirus.

Alpha coronavirus and Beta coronavirus predominantly infect mammals (Human as well) Of the coronaviruses known so far, SARS-CoV-2 is a novel member of the beta coronavirus genus. The first cases emerged in December 2019 in Wuhan, China.
On 30th January 2020 the World Health Organization confirmed the outbreak as a public health emergency of international concern and on March 11, 2020, they declared it a global pandemic. Coronavirus disease is an ongoing global public health problem and most of the COVID-19 research mainly focuses on the respiratory system because of life-threatening results.
However, manifestations in other organs should not ignore, since they can also be a mode of transmission. Likewise, the ocular mode of transmission also suspected to date. In fact, there are increasing reports suggesting that a few COVID-19 cases began with ocular infection as the initial symptom following contact with the infected person.

Morphology

Corona viruses are termed as ‘enveloped’ due to lipid membrane that surrounds their capsid (protein). Capsid contains RNA as the genetic material. Proteins protrude from their lipid envelope giving crown like appearance to them and hence the term “corona” is used for the virus.

It contains 4 types of protein: Membrane, Nucleocapsid, Structural, and Spike. Spike protein is involved in binding to the host cells whereas the rest are mainly involved in forming and structuring the virus.

Mode of Transmission

Human to human transmission through direct contact and droplet transmission while coughing, sneezing, breathing, and talking without maintaining any physical distancing. Contaminated objects or surfaces from an infected person. Indirect viral acquisition from fomites, through the mucous membranes of the mouth, eyes, and nose. Though ocular transmission remains controversial, it is also a suspected route.

Possible Route of Transmission from conjunctiva

The eye appears to play a key role in virus downstream transmission since it is an open microenvironment. Following are the ways on the ocular mode of transmission.

  1. Direct inoculation to the ocular tissues from respiratory droplets or aerosolized viral particles.
  2. Touching the nose by hands contaminated with virus from tears.
  3. Migration from the nasopharynx to the respiratory tract through the nasolacrimal duct.
  4. Hematogenous spend through the lacrimal gland.

How virus replicate in Ocular Tissues?

The eye constitutes a potential site of coronavirus replication as that of the respiratory tract.

  1. SARs-CoV2 binds to Angiotensin-Converting Enzyme 2 (ACE 2) to facilitate infection in humans.
  2. The spike protein present in the virus helps in its binding to the host.
  3. The binding required to infect the cells.

Importantly, ACE 2 receptors have identified in the eye not only on the ocular surfaces such as cornea and conjunctiva but also in deeper intraocular tissues such as retina.

Ocular Manifestations

Conjunctivitis may occur as a sole manifestation of COVID-19 which needs to be carefully evaluated by health care workers and eye care professionals during the pandemic. However, ocular manifestation found to be rare in COVID-19 patients.
Ocular symptoms include:

  1. Redness
  2. Photophobia
  3. Itchiness
  4. Burning Sensation
  5. Foreign Body Sensation
  6. Tearing

Why is there rare ocular manifestation?

  1. The ocular tissues comprise the above defense mechanism.
  2. Mechanical barriers comprise the eyelids and eyelashes. The tight intercellular junctions of the corneal epithelium and conjunctival mucosa.
  3. Tears contain anti-microbial proteins such as Lactoferrin and immunoglobulins.
  4. Lactoferrin inhibits the binding of the viral particles to the ocular tissues.
  5. Tear IgA has proven to provide an effective immune against a wide variety of viruses.
  6. The Lacrimal Drainage System acts as a physical self-cleaning system that clears the pathogen from the ocular system.

Evaluation

  1. Through History to rule out any travel history and presence of any COVID-19 symptoms.
  2. Measurement of Visual Acuity.
  3. Anterior segment examination.
  4. Intraocular Pressure measurement.
  5. RT-PCR of conjunctival secretion collected with swab since tears and conjunctival secretions might contain viral particles in the infected person.

Management

An ocular manifestation of COVID-19 pretended to be self-limited and managed with symptomatic care. Frequent preservative-free artificial tears, cold compress, and lubricating ophthalmic ointment along with topical antibiotics can a Medication Therapy.

Let’s protect our EYES in this pandemic.
Let’s Have our EYE PROTECTION compulsory.