Discussion
Episcleritis has been previously found in a patient confirmed with
COVID-19 infection (8, 9). In this report, we presented a case of
scleritis after the third dose of COVID-19 vaccination with inactivated
Sinopharm vaccine. Recently, Pichi and colleagues reported four cases
scleritis and episcleritis following the first dose of COVID-19
Sinopharm vaccination (10). There has been few reports of mild scleritis
or episcleritis caused by live virus vaccination previously (11).
Regarding various reports of ocular adverse events induced after
vaccination, COVID-19 vaccination-associated scleritis would not be
exempt in surprising. The pathogenesis and mechanism of this immune
response, remains the question. The most frequently proposed mechanism
include molecular mimicry between scleral and vaccine peptides as well
as hypersensitivity due to antigen-specific cell and antibody reactions
(12). Moreover, although safe in most of the population, vaccine
adjuvants that were added to achieve the desired protection, led to
autoinflammatory syndromes particularly connective tissue disorders due
to different nucleic acid metabolism (9, 13, 14). Noteworthy,
inactivated COVID-19 vaccines stimulate T helper 2 cell reactions
causing an increase in inflammatory (15). The addition of alum as an
adjuvant aggravated immunopathologic reactions (16).
The genes for immunity, inflammation, and coagulation are part of X
chromosome, so we may suspect that viral interactions associated with
human genes could induce an abnormal immune response in COVID-19.
Besides, according to Manzo et al., the presence of excess antigen and
the formation of relatively resistant soluble antigen-antibody immune
complexes after exposure to SARS-CoV-2 may cause persistent inflammation
in organs (17). There are several reported cases of ocular inflammation
and related conditions following COVID-19 vaccination. These include
anterior uveitis (7, 18), scleritis (7), episcleritis (7), multiple
evanescent white dot syndrome, Vogt-Koyanagi-Harada disease (19),
panuveitis (20), choroiditis (21), and central serous chorioretinopathy
(22). Most cases were successfully treated with corticosteroid therapy,
including topical, intravitreal, and/or systemic administration, and
many patients achieved complete recovery of their baseline visual
acuity. A case series of orbital inflammation following mRNA vaccines
was also described, with all cases successfully treated with oral
prednisolone (23). It is important for healthcare providers to be aware
of these potential ocular reactions to COVID-19 vaccination and to
monitor patients closely for any signs or symptoms of ocular
inflammation or related conditions.
As mentioned, our patient didn’t show any serious reaction to previous
doses of inoculation until the first booster. These reactions were found
to be induced by activation of the secondary immune response; the memory
cells (24). Comparing to the first and second doses of vaccinations,
Rahmani et al. Reported that booster doses are more probable to
stimulate rare AEs including neurological symptoms (25). Moreover,
authors suggested hormonal, genetic, and behavioural factors along with
the time between the primary cycle to the first booster dose. The more
the time between the booster dose and the first administration, the
higher the immunogenic effect after the third shot (25). Consequently,
further studies could elucidate the proper time of the booster
inoculations, particularly for high-risk patients in order to prevent
serious reactions.
Vaccine-associated maladaptive immune response becomes more important in
patients with autoimmune diseases. A study demonstrated that ocular
inflammatory AEs following vaccination could be the first presentation
of an undiagnosed autoimmune disease (26). Thus, there should be further
assessments in patients presenting with ophthalmologic inflammatory
reactions following COVID-19 vaccination.