INTRODUCTION
The latest pandemic, which started on December 31st, 2019, when cases of
pneumonia of unknown etiology in Wuhan, Hubei province of China, were
reported to the World Health Organization (WHO), has continued with the
identification of a new coronavirus (2019-nCoV), and this new virus has
spread rapidly and become a global problem. The new virus was named
(SARS-CoV-2) due to its close similarity to severe acute respiratory
syndrome coronavirus (SARS-CoV), and the disease caused by the virus was
named COVID-19. In limited studies for SARS-CoV-2, the average
incubation period has been determined as 5-6 days. Symptoms may occur
within 2-14 days after contact and contamination may begin 1-2 days
earlier. In the clinical presentation of COVID-19, fever, dry cough, and
respiratory distress are considered as major findings (1,2). Although
patients mostly present with an asymptomatic or mild clinical picture,
it may progress to pneumonia or acute respiratory distress syndrome in
patients with additional disease and those aged over 65 years (3)(4).
Infection is transmitted from person to person by inhalation of droplets
or contact with the eyes, nose, and mouth after touching surfaces
contaminated by the virus (5).
Some respiratory system viruses such as adenovirus and H7 influenza
virus can strongly stimulate the immune system in the cornea and
conjunctiva, causing the inflammatory pathway to be activated and to
consequently form conjunctivitis or keratoconjunctivitis (6).
Coronaviruses that can cause conjunctivitis in humans have also been
reported. Human coronavirus NL 63 (HCoV-NL63) was first identified with
bronchiolitis and conjunctivitis in an infant. Then, conjunctivitis was
defined in 17% of 29 In pediatric patients with HCoV-NL63. No ocular
involvement was reported in Middle East respiratory syndrome-related
coronavirus (MERS-CoV) or SARS-CoV infections (7). However, in animal
studies, ocular infection was observed as a result of direct inoculation
of SARS-COV in the mouth, nose or eye (8)(9)(10). A tear film mostly
covers the eye surface and prevents bacteria and viruses from adhering
to the cornea and conjunctiva with antimicrobial agents and the
immunoglobulins it contains (11).
It has been shown that SARS-CoV-2 infects host cells via
angiotensin-converting enzyme 2 (ACE2) just like SARS-CoV and has
similar receptor binding sites (12). ACE-2 receptor has been detected in
the retina (13), choroid (14) and conjunctival epithelium (15) in the
human eye. In previous studies, findings such as acute follicular
conjunctivitis, conjunctival hyperemia, chemosis, epiphora, and
increased secretion have been described in patients with COVID-19 (16).
As with other viral infections, it is assumed that the ocular symptoms
of COVID-19 are self-limited and can be managed with symptomatic
treatment.
It is known that SARS-COV-2 can be found in tears and adhere to the
ocular surface. Conjunctivitis in patients with COVID-19 has been
reported at different rates in various studies. It is not clear whether
it causes different findings or subclinical conditions on the ocular
surface.
The aim of this study was to evaluate the frequency of ocular
involvement in hospitalized patients with COVID-19 and to compare the
demographic findings and various blood parameters of patients with and
without ocular findings.