Background/Objectives: This study aimed to analyze optic nerve parameters, retinal nerve fiber layer thickness (RNFLT), ganglion cell layer thickness (GCLT), and subfoveal choroidal thickness (ChT) in patients who have recovered from coronavirus disease 2019 (COVID-19). Methods: This comparative study included 78 recovered COVID-19 patients (16 men, 62 women) and 56 age- and sex-matched healthy controls (18 men, 38 women). COVID-19 was confirmed in all patients, either through the detection of viral RNA in nasopharyngeal swabs via reverse transcriptase polymerase chain reaction or by serological testing for SARS-CoV-2 antibodies. Spectral-domain optical coherence tomography (SD-OCT) was used to assess optic nerve parameters, RNFLT, GCLT, and ChT. Results: The mean age was 35.0 ± 8.3 years in the COVID-19 group and 31.5 ± 8.3 years in the control group, with no statistically significant differences in age or sex distribution between groups (p = 0.41 and p = 0.16, respectively). Optic nerve parameters and RNFLT (overall and across the four peripapillary quadrants) did not differ significantly between the COVID-19 and control groups. However, the mean ganglion cell-inner plexiform layer (GC-IPL) thickness was significantly reduced in all quadrants in the COVID-19 group compared to the controls. No significant difference was observed in mean subfoveal ChT between groups. Conclusions: A significant reduction in ganglion GCLT was observed in recovered COVID-19 patients compared to healthy controls, suggesting a potential neurodegenerative effect of the disease on the optic nerve.

To evaluate the impact of coronavirus disease 2019 (COVID-19) on postoperative visual acuity, optical quality, and severity of dry eye disease in patients after small incision lenticule extraction (SMILE).

This is a retrospective, comparative study. Patients who underwent SMILE were included and divided into two groups according to the period at the eye center of the Second Affiliated Hospital of Zhejiang University. The first group included patients who underwent SMILE before the large-scale COVID-19 pandemic in China (Group 1). The second group comprised patients who underwent SMILE during the pandemic with a confirmed infection of COVID-19 (Group 2). The visual acuity, the severity of dry eye, ocular surface disease index (OSDI), oculus keratography analysis, and individual Zernike coefficients were evaluated and compared between the 2 groups.

A total of 43 eyes of 23 patients and 45 eyes of 26 patients were included in Groups 1 and 2, respectively. The OSDI score in Group 2 was significantly higher than Group 1 (P ​< ​0.01). The corrected distance visual acuity (CDVA, logMAR) at 3 months postoperatively in Group 1 was better than in Group 2 (P ​< ​0.001). Despite the improvement over 1 month after the COVID-19 infection, the OSDI score was still higher in Group 2 than in Group 1 (P ​< ​0.01). The bulbar and limbal redness were significantly higher in Group 2 than in Group 1 ​at both 1 month and 3 months (P ​< ​0.05), while no significant differences were found in tear breakup time or tear meniscus height. Spherical aberration (SA) at the 4 ​mm zone was significantly higher in Group 2 than in Group 1 both at 1 month and 3 months (P ​< ​0.001), while no significant changes were observed in corneal total higher-order aberrations. No significant correlation was found between the bulbar/limbal redness index and SA.

COVID-19 infection impaired visual outcomes and aggravated dry eye severity among postoperative SMILE patients.

Our study aimed to investigate the prevalence and timing of ocular surface manifestations in hospitalized COVID-19 patients, providing insights into the occurrence of eye involvement before, during, or after the illness. This study contributes to understanding the extent of ocular involvement in COVID-19, which has been suggested to occur due to potential viral entry through the eyes.

451 confirmed COVID-19 patients had a history of hospitalization in Styria, Austria. The study included 176 patients aged 18-95 years who tested positive for SARS-CoV-2 in nasopharyngeal swabs by RT-PCR and received treatment at two hospitals. Telephone interviews were conducted after recovery, focusing on ocular symptoms and medical history (openMEDOCS).

Seventeen percent (n=30) reported new-onset ocular symptoms in the context of COVID-19. Patients with ocular symptoms were younger (p<0.001). Sore throat (p=0.013) and high fever (p=0.038) were significantly more prevalent in patients with new-onset ocular symptoms. Persistent ocular symptoms beyond the duration of hospitalization affected more than half (56.7%) of the participants with new-onset ocular symptoms. However, there were no differences in blood parameters, lung imaging, or comorbidities between groups with and without ocular symptoms.

In hospitalized COVID-19 patients, ocular symptoms occur with a significant prevalence of 17%. Younger age (p<0.001) and the presence of sore throat (p=0.013) are associated with an increased risk of developing new-onset ocular symptoms in the context of COVID-19.

We aimed to investigate changes in the ocular disease spectrum during the coronavirus disease-2019 (COVID-19) pandemic in late 2022 in the Hubei Province. This retrospective observational study was conducted in two parts. The first part involved collecting COVID-19-related information from residents of Hubei Province through an online questionnaire survey. The second part involved extracting electronic medical records from ophthalmology outpatient departments at two hospitals in Hubei Province during the pandemic and epidemic prevention and control periods, analyzing changes in the spectrum of ocular diseases. In the first part, 31.65% of patients with systemic symptoms of COVID-19 experienced ocular discomfort. The most common ocular symptoms were eye fatigue, ocular pain and dry eye. In the second part, 76.5% of patients who visited the ophthalmic clinic had COVID-19-related systemic symptoms during pandemic period. The proportion of patients with cornea/keratitis, glaucoma/acute angle-closure glaucoma (AACG) and vitreoretinal disease/retinal vein obstruction (RVO)/acute macular neuroretinalpathy (AMN) increased markedly during pandemic period. Additionally, the number of patients under 18 years and over 60 years decreased significantly compared to the same age groups pre- & post-pandemic. The COVID-19 pandemic has led to certain changes in the spectrum of ocular diseases, which warrants the attention of ophthalmologists.

With the consistent occurrence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, the prevalence of various ocular complications has increased over time. SARS-CoV-2 infection has been shown to have neurotropism and therefore to lead to not only peripheral inflammatory responses but also neuroinflammation. Because the receptor for SARS-CoV-2, angiotensin-converting enzyme 2 (ACE2), can be found in many intraocular tissues, coronavirus disease 2019 (COVID-19) may also contribute to persistent intraocular neuroinflammation, microcirculation dysfunction and ocular symptoms. Increased awareness of neuroinflammation and future research on interventional strategies for SARS-CoV-2 infection are important for improving long-term outcomes, reducing disease burden, and improving quality of life. Therefore, the aim of this review is to focus on SARS-CoV-2 infection and intraocular neuroinflammation and to discuss current evidence and future perspectives, especially possible connections between conditions and potential treatment strategies.

In the third wave of the coronavirus disease 2019 (COVID-19) pandemic, despite progressive vaccination coverage, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was rapidly spreading and the possibility for ocular transmission of COVID-19 was most relevant. This study aimed to determine the presence of SARS-CoV-2 RNA in tears as detected by real-time polymerase chain reaction (RT-PCR), among individuals who tested COVID-positive during the third wave of the COVID pandemic.

Among 90 patients admitted with mild to severe COVID-19 infection (ranging from asymptomatic to severe symptoms), separate conjunctival samples were obtained from both eyes without topical anesthesia taking precautions to avoid contamination. Inferior fornices of the eyes were swept slowly with sterile Dacron swabs for 10 s or until visibly wet. They were inoculated directly in a viral lysis buffer containing carrier RNA and transported to the Virology Laboratory for the detection of SARS-CoV-2 RNA by RT-PCR. Conjunctival swabs were declared positive based on cycle threshold values of <37.

Seven of 180 conjunctival swabs were positive (3.9%). Five patients had unilateral positive and one patient had bilateral positive conjunctival swabs. Thirty-six (40%) patients had their conjunctival swabs taken on the same day of detection of the first positive nasopharyngeal swab, while the rest (54) had their conjunctival swabs taken up to 3 days later. Overall, 20 (22.2%) patients were symptomatic for COVID-19.

Considering the contagious nature of SARS-CoV-2 in the third wave, there is a possibility that ocular surface fluid might have been a contributing factor along with other modes of transmission of COVID-19.

This study aimed to evaluate ocular surface temperature (OST) in post-COVID-19 patients with different degrees of fever via infrared thermal imaging. There were 16 participants (32 eyes) in the control group, 22 participants (44 eyes) in the moderate and low post-COVID-19 fever group (M & L fever group), and 18 participants (36 eyes) in the high post-COVID-19 fever group (H fever group). All participants underwent an ophthalmic slit lamp examination and ocular thermography. Among the control group, M & L fever group and H fever group, there were no significant differences in the upper eyelid temperature (UET), inner canthus temperature (ICT), outer canthus temperature (OCT), initial central corneal temperature (initial CCT), third-second central corneal temperature (3s-CCT), or sixth-second central corneal temperature (6s-CCT). However, the change in central corneal temperature measured within 1, 3, and 6 s (change in CCT within 1, 3, and 6 s) of the H fever group were significantly greater than those of the control group (0.15 ± 0.12 °C vs. 0.08 ± 0.09 °C, p = 0.007; 0.30 ± 0.22 °C vs. 0.17 ± 0.17 °C, p = 0.005; 0.45 ± 0.30 °C vs. 0.26 ± 0.23 °C, p = 0.004, respectively) and M & L fever group (0.15 ± 0.12 °C vs. 0.08 ± 0.08 °C, p = 0.008; 0.30 ± 0.22 °C vs. 0.16 ± 0.14 °C, p = 0.001; 0.45 ± 0.30 °C vs. 0.23 ± 0.20 °C, p < 0.001, respectively). To further investigate the relationship between OST and post-COVID-19 fever, we compared the OST of long recovery time (5 days < recovery time < 14 days; 9 patients, 18 eyes) and short recovery time (recovery time ≤ 5 days; 9 patients, 18 eyes) in the H fever group. We found that the 6s-CCT in the short recovery time group was significantly lower than that in the long recovery time group (32.43 ± 1.09 °C vs.33.10 ± 0.82 °C, p = 0.044). Additionally, the change in CCT within 1 s, 3 s, and 6 s in the short recovery time group were all significantly greater than those in the long recovery time group (0.19 ± 0.13 °C vs. 0.11 ± 0.10 °C, p = 0.048; 0.38 ± 0.24 °C vs. 0.22 ± 0.17 °C, p = 0.026; 0.58 ± 0.31 °C vs. 0.32 ± 0.24 °C, p = 0.016, respectively). In conclusion, the central corneal temperature (CCT) of patients who have an insufficient recovery time from COVID-19 infection or who exhibit severe infection symptoms could decrease faster when the eyes open. This may be due to dry eye disease.

Macular damage is a rare yet significant ocular complication of coronavirus disease 2019 (COVID-19) infection. This report highlights the clinical features, diagnosis, treatment, and outcomes in 2 cases of COVID-19-associated macular damage, contributing to the understanding of its pathophysiology and management.

Both patients presented with a sudden onset of visual impairment and black shadows in their central visual fields shortly after contracting COVID-19.

The first patient, a 15-year-old male, was diagnosed with acute macular neuroretinopathy, evidenced by optical coherence tomography (OCT) imaging showing high-density shadows in the macular area. The second patient, a 28-year-old female, presented with more extensive macular lesions, confirmed via fundus photography and OCT imaging.

Both patients received systemic corticosteroid therapy (oral prednisone acetate, 30 mg daily). The male patient was treated for 5 days, while the female patient underwent a 3-day treatment course.

The male patient showed significant improvement in visual acuity, with OCT imaging revealing the resolution of high-density shadows but persistent disruption of the ellipsoid zone. The female patient demonstrated partial improvement in visual symptoms, though residual macular abnormalities remained evident on imaging.

COVID-19-associated macular damage appears to involve inflammatory and vascular mechanisms. Early systemic corticosteroid therapy may offer symptomatic relief and partially restore visual function. However, long-term monitoring is essential to address potential residual or progressive retinal damage.

This study aimed to report the ocular manifestations in individuals with coronavirus disease 2019 (COVID-19) and investigate any correlation between the occurrence of ocular symptoms and systemic symptoms.

A retrospective electronic survey was conducted among the general public in northern China from December 2022 through February 2023. Inclusion criteria for COVID-19 was confirmed testing positive via a polymerase chain reaction (PCR) test or testing positive for COVID-19 via an antigen kit. The anonymous survey collected information on demographics, systemic COVID-19 symptoms, ocular diagnosis and symptoms, comorbidities and disease history.

A total of 2,405 survey responses were collected and the final analysis included individuals in the 335 COVID-19 positive group and 434 individuals in the COVID-19 negative group. Among COVID-19 positive patients 66.3% (n = 222) reported experiencing ocular symptoms. Dryness (n = 106, 31.6%), blurred vision (n = 81, 24.2%), eye pain (n = 72, 21.5%), and itching (n = 71, 21.2%) were the main features. COVID-19 was found to be associated with a higher prevalence of conjunctivitis, iritis, uveitis, retinal vein occlusion and optic neuritis. The majority of individuals (51.0%) developed eye symptoms after the onset of COVID-19 systemic symptoms. There was no significant association between the severity of systemic symptoms and ocular symptoms.

Individuals with COVID-19 were significantly more likely to experience ocular symptoms. COVID-19 was found to be associated with a higher prevalence of retinal diseases. The majority of individuals developed ocular symptoms right after the onset of systemic symptoms.

COVID-19, caused by SARS-CoV-2, has presented formidable challenges to global health since its emergence in late 2019. While primarily known for respiratory symptoms, it can also affect the ocular surface. This review summarizes the effects of SARS-CoV-2 on ocular surface immunity and inflammation, focusing on infection mechanisms, immune responses, and clinical manifestations. Ocular symptoms, though uncommon, include conjunctivitis, dry eye, and blurred vision. SARS-CoV-2 binds to ACE2 receptors in ocular surface epithelial cells, facilitating viral entry, replication, and local dissemination. The innate immune responses involving corneal epithelial cells and immune cells are discussed, alongside mechanisms of antigen presentation and adaptive immunity. The review also examines the roles of cytokines and chemokines in mediating ocular surface inflammation and explores the impact of cytokine storms and chronic inflammation on ocular health. Additionally, the interplay between systemic and ocular immune responses is highlighted, analyzing how systemic COVID-19 inflammation influences ocular surface health. These insights underscore the broader implications of COVID-19 beyond localized ocular infection. By consolidating current findings, this review aims to guide preventive and therapeutic strategies while identifying directions for future research to mitigate the ocular consequences of COVID-19.

The SARS-CoV-2 virus that resulted in the COVID-19 pandemic has been implicated in a range of neurological issues, such as encephalopathy, stroke, and cognitive decline. Although the precise mechanism causing these issues is unknown, mounting evidence shows that blood-brain barrier (BBB) disruption is probable2 a major factor. The integrity of the blood-brain barrier (BBB), a highly selective barrier that divides the brain from the systemic circulation, is crucial for preserving normal brain function. By analysing the multi-transcriptome data, this work explores the neurological impacts of the SARS-CoV-2 virus and provides insight into the molecular mechanisms behind BBB breakdown and neurological symptoms in COVID-19 patients. The endothelial cells of BBB expresses inflammatory genes in response to the systemic inflammation induced due to SARS-CoV-2 remnants in the body. This raises the possibility that systemic inflammation brought on by SARS-CoV-2 and BBB integrity are correlated. Furthermore, the study highlights the pathways involved in oxidative stress and endothelial cell activation, revealing their role in COVID-19 passage through BBB and induction of systemic inflammation and advancement toward neurological disorders. The article showcases the evidence that mitochondrial dysfunction is a major aftermath associated with SARS-CoV-2 infection as the impaired Mitochondria leads to an accumulation of reactive oxygen species (ROS), triggering endothelial dysfunction, and leading to the passage of harmful molecules across the BBB. This study offers insightful information that may open up the possibilities for new treatment plans by targeting biomarkers specifically associated with inflammation and BBB dysfunctioning conditions.

We report a case of chronic dacryoadenitis associated with SARS-CoV-2, confirmed by histological analysis. A previously healthy school-aged boy was admitted to the paediatric department with a 1 month history of both eyebrow swelling and very mild pain in the upper parts of both eyelids. Gadolinium-enhanced T1-weighted MRI revealed enlargement of both lacrimal glands. Clinicopathological analysis confirmed bilateral chronic dacryoadenitis. Topical steroids were given, resulting in slow resolution over 2 months, and clinical stability at 10 months. The patient had experienced mild respiratory symptoms and tested positive for SARS-CoV-2 antigen via PCR testing, diagnosed as SARS-CoV-2, 3 months prior to the onset of dacryoadenitis. Inflammatory cells around the lacrimal gland demonstrated immunoreactivity for SARS-CoV-2 nucleocapsid protein. However, PCR testing of lacrimal fluid for SARS-CoV-2 was negative. This case illustrates protean complications and suggests a probable pathogenetic mechanism of dacryoadenitis associated with SARS-CoV-2.

To determine whether severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection affects corneal morphology and optical quality.

In this cross-sectional study, ophthalmological indicators were examined during the peak of SARS-CoV-2 infection after adjusting for public health control measures. Participants were divided into control (remained uninfected), A (infected during follow-up), and B (infected prior to the first consultation) groups. Effects of varying SARS-CoV-2 infection levels were determined using reverse transcription polymerase chain reaction. Changes in corneal morphology, backscatter, and aberrations were measured. Corneal parameters, such as flat keratometry, steep keratometry, and surface variance, vertical asymmetry, height asymmetry, and height decentration indices were considered.

Overall, 110 participants (208 eyes, 42.7 % male; age 17-31 years) were enrolled. Eighteen (16.3 %) were infection-free during the outbreak with unchanged corneal morphology, backscatter, and aberration. In group A, 34.73 ± 9.30 days after infection, the backscatter of the anterior corneal layer and central layer (both p = 0.000) decreased. Total low-order aberration, defocus, horizontal coma, and spherical aberration of the cornea increased (p < 0.05), while corneal morphology after infection did not change (p > 0.05). In group B, a decrease in backscattering in the corneal middle layer and an increase in horizontal coma (p < 0.05) were noted.

Backscattering of the anterior and intermediate layers of the cornea decreased and corneal aberrations increased after SARS-CoV-2 infection, which affected corneal optical quality. However, corneal morphology and thickness remained unchanged. Ophthalmological indicators and optical quality should be monitored during SARS-CoV-2 infection.

To systematically review the characteristics of patients experiencing acute angle closure (AAC) attacks during the COVID-19 outbreak in Beijing. Patients with AAC attacks during the COVID-19 epidemic and those in the same period the following year were recruited. Demographic characteristics, ocular biometry, ocular signs, sequential relationships, and the prognosis of operative management outcome were recorded and compared between the 2 groups. We included 60 eyes of 55 patients with AAC attacks in the COVID-19 group and 34 eyes of 33 patients in the control group. There was a significantly higher incidence of bilateral attacks during the COVID-19 outbreak compared to the control group (9 vs 1, P = .043). Additionally, a higher proportion of AAC attacks were observed in the COVID-19 group (P = .035). The COVID-19 group had a higher mean peak intraocular pressure (53.42 ± 8.87 mm Hg vs 47.86 ± 11.22 mm Hg; P = .007), larger pupil diameter (5.75 ± 1.04 mm vs 4.86 ± 1.26 mm; P < .001), more pigmented keratic precipitates (39 vs 8, P < .001), and segmental atrophy of the iris (32 vs 10, P = .019). Coronavirus infection was simultaneous with or slightly preceded the appearance of AAC attacks. Most patients had an ideal prognosis after comprehensive management. An increased incidence of AAC attacks, more bilateral cases and severe anterior segment inflammation were observed during the COVID-19 outbreak in Beijing. There may be a correlation between the onset of AAC attacks and coronavirus infection, but further research is needed to explore this link.

Background Coronavirus disease (COVID-19), a widespread viral illness, has been linked to a range of respiratory and other systemic symptoms. Along with the respiratory symptoms caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2), many extrapulmonary manifestations have also been reported. This study was conducted to report the ocular manifestations of COVID-19 in confirmed cases from the Qassim region, of Saudi Arabia. Methods In this retrospective survey-based study, an electronic survey was distributed via social media to individuals who reported a positive COVID-19 test. Demographic data, medical and ocular history, and data about their COVID-19 infection and ocular symptoms were collected. Results A total of 200 survey responses were included (35% male and 65% female, age 30.3 years). At least one ocular symptom was reported by 41 (20.5%) participants. Light sensitivity (8.5%), blurred vision (7.5%), redness (7.0%), and eye pain (7.0%) were the most common ocular symptoms. Conclusion Among the study participants, ocular symptoms were reported by more than one-fifth of the COVID-19 patients. These ocular symptoms were mostly mild. Further research is required to fully understand the association between COVID-19 and ocular manifestations.

The pandemic COVID-19 (coronavirus disease 2019) is caused by the severe acute respiratory syndrome corona virus 2 (SARS-CoV-2), which devastated the global economy and healthcare system. The infection caused an unforeseen rise in COVID-19 patients and increased the mortality rate globally. This study gives an overall idea about host-pathogen interaction, immune responses to COVID-19, recovery status of infection, targeted organs and complications associated, and comparison of post-infection immunity in convalescent subjects and non-infected individuals. The emergence of the variants and episodes of COVID-19 infections made the situation worsen. The timely introduction of vaccines and precautionary measures helped control the infection's severity. Later, the population that recovered from COVID-19 grew significantly. However, understanding the impact of healthcare issues resulting after infection is paramount for improving an individual's health status. It is now recognised that COVID-19 infection affects multiple organs and exhibits a broad range of clinical manifestations. So, post COVID-19 infection creates a high risk in individuals with already prevailing health complications. The identification of post-COVID-19-related health issues and their appropriate management is of greater importance to improving patient's quality of life. The persistence, sequelae and other medical complications that normally last from weeks to months after the recovery of the initial infection are involved with COVID-19. A multi-disciplinary approach is necessary for the development of preventive measures, techniques for rehabilitation and strategies for clinical management when it comes to long-term care.

Acute macular neuroretinopathy (AMN) is a rare disease that causes transient or permanent visual disturbance. The exact etiology remains unknown, but vascular compromise of the deep retinal capillary plexus was postulated as the main mechanism. Retinal vascular event post-coronavirus disease 2019 (COVID-19) infection is recently highlighted during the pandemic, which includes AMN.

To report a case of AMN post-COVID-19 infection.

A 24-year-old Indian woman presented with acute-onset painless bilateral central scotoma for a day. The symptom was preceded by a history of COVID-19 infection 3 weeks prior. Ocular examination revealed a near-normal visual acuity for both eyes. Fundus examination showed bilateral dull foveal reflex with mild scattered cotton wool spot and vascular tortuosity. Optical coherence tomography macula revealed a distinct short hyperreflective band involving the outer plexiform and outer nuclear layers nasal to the fovea. The Bjerrum perimetry test revealed central scotoma temporal to the fixation. Optical coherence tomography lesions and scotomas are identical and congruous in both eyes. Serial fundus photographs are captured showing the evolving changes of near-normal macula to pigmented wedge-shaped petaloid lesions around the fovea. The patient was diagnosed as bilateral AMN and treated with oral prednisolone. On subsequent follow-up, the central scotoma improved.

This case illustrates a clear temporal and possible causal relationship of COVID-19 infection with AMN. Further studies and data are required to justify its association, but the rising cases of AMN shall be anticipated as COVID-19 infections have become endemic worldwide.

Acute angle-closure glaucoma (AACG) is a major cause of irreversible and severe visual function loss. Robust rise in AACG was observed in the ophthalmic outpatient clinics concomitant with the outbreak of COVID-19 infection in China after the relaxing of "zero-COVID policy" in early December 2022. Here we compared the demographic and clinical profiles of patients with AACG before, during and after the COVID-19 outbreak. Underlying mechanisms were tentatively investigated.

This is a retrospective comparative study. Consecutive cases with newly diagnosed AACGs in a tertiary eye hospital were retrospectively collected during December 17, 2022 to January 8, 2023. Data from the same period in 2018-2019 and 2019-2020, 2020-2021 and 2021-2022, and 2023-2024 were collected as pre-pandemic, pandemic-control, and post-pandemic control, respectively. For the patients in 2022-2023 outbreak group, COVID-19 infection was confirmed by reversed transcriptase-polymerase chain reaction or antibody test for severe acute respiratory syndrome coronavirus disease 2 (SARS-CoV-2) from nasopharyngeal swabs. Ocular parameters, serum electrolytes and coagulative parameters were compared between COVID-19 positive and negative AACGs in observational group. SARS-CoV-2 nucleic acid in the aqueous humor was detected.

A total of 106 AACG cases were diagnosed during the outbreak period in 2022-2023. In contrast, 18 (in 2018-2019) and 22 (in 2019-2020) cases were included during pre-pandemic period, and 21 (in 2023-2024) during the post-pandemic period. Only 13 and 4 newly onset AACG were included in 2020-2021 and 2021-2022 during the pandemic-control period, respectively. Younger age and higher proportion of bilateral involvement were detected in COVID-19 outbreak group than that of other groups (p = 0.034 and p = 0.080). Sixty-eight (64.2 %) patients in the outbreak group had a confirmed COVID-19 infection. Intervals between infection and AACG attack was 52 ± 85h (0-15d). Fifty-three patients (77.9 %) reported the applications of ibuprofen or other antipyretic medications and 25 (36.8 %) reported large volume water intake before AACG attack. COVID-19-positive AACG patients had higher level of D-dimer than their negative counterparts (1.13 ± 2.60 mg/L vs. 0.46 ± 0.43 mg/L, p = 0.083). No difference in IOP, serum electrolytes, and coagulative parameters other than D-dimer was observed between COVID-19 positive and negative cases. SARS-CoV-2 were negative in the aqueous humor from 14 COVID-19 positive and 8 negative patients.

COVID-19 infection surged the onset of AACG in patients at risk. Mental stress, water intake, increased choroidal thickness due to SARS-CoV-2 induced ACE receptor activation, and hyper-coagulation, may contribute to the disease onset. Ocular involvement should not be ignored in both routine and new systemic emergent conditions.

Our aim was to evaluate a potential role for the lacrimal drainage system (LDS) as a portal of entry and conduit for SARS-CoV-2 in human infection. We also investigate the mucosal surface area. The relatively long tear contact time in a closed system raises the possibility that this pathway may contribute to the initiation of systemic infection. We looked for expression of ACE2, the main receptor for SARS-CoV-2, as well as cofactors such as TMPRSS2 and other enzymes such as cathepsinB, CD147, elastase1, furin, neuropilin1, neuropilin2, TMPRSS11D and trypsin which also play a role in SARS-CoV-2 infection, in this system.

Human tissue samples of the draining tear ducts from body donors were analyzed by RT-PCR, Western blot and immunohistochemistry. It is not known whether the respective body donors were Sars-Cov-2 positive at any time; they were negative when they entered the institute. Besides, the draining LDS of body donors were measured to determine the mucosal surface in the lacrimal system.

The expression of the main receptor studied, ACE2, cofactors such as TMPRSS2 and other enzymes such as cathepsinB, CD147, elastase1, furin, neuropilin1, neuropilin2, TMPRSS11D and trypsin were all detected at the gene and protein level. The average mucosal surface area of the lacrimal sac and nasolacrimal duct was calculated to be 110 mm2.

The results show the presence of all analyzed receptors in the efferent LDS. With an average tear passage time of 3 min and a relatively large mucosal surface area, the LDS could therefore be considered as a portal of entry and conduit for SARS-CoV-2. In addition, it represents a surface that should be taken into consideration in the administration of topically applied medication to the ocular surface.

To study the positivity rate of conjunctival realtime polymerase chain reaction (RT-PCR) testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Systematic review and diagnostic accuracy meta-analysis.

MEDLINE and EMBASE were queried using medical subject headings terms. Diagnostic accuracy meta-analyses and forest plots were obtained using the RevMan software.

After deduplication, appraisal of abstract titles and full-text analysis of 1441 articles, 42 articles with 3351 COVID-19 patients were included in this review. Of these, 412 conjunctival swabs/Schirmer paper strips tested positive for SARS-CoV-2 by RT-PCR. The pooled sensitivity of the RT-PCR tests across the 24 studies with laboratory-confirmed COVID-19 patients was 10.3%.

Only 1 in 10 RT-PCR tests performed on conjunctival swabs were positive for SARS-CoV-2. Although this suggests that SARS-CoV-2 is likely present and detectable in the conjunctiva, this detection method has low diagnostic potential.

Our study aims to build on our understanding of COVID-19 by detailing a comprehensive look at the prevalence of different ocular manifestations related to COVID-19 infection.

Systematic review and meta-analysis.

Eligible studies published between June 20, 2021, and May 11, 2023, were retrieved from the MEDLINE, EMBASE, and CINAHL databases as well as grey literature. Covidence was used to conduct the systematic review. Duplicate records were removed, and 2 independent reviewers screened records for relevance. After screening, a risk-of-bias assessment was carried out. Data were extracted, and a meta-analysis was performed using STATA 14.0. Fixed-effects and random-effects models were computed based on heterogeneity.

Our meta-analysis included 43 articles with a total of 10,572 subjects. The results showed that COVID-19 patients had a significantly higher prevalence of conjunctivitis (effect size [ES] = 0.11; 95% CI, 0.07-0.15), ptosis (ES = 0.22; 95% CI, 0.15-0.30), and ophthalmoplegia (ES = 0.40; 95% CI, 0.06-0.74). Our results also indicate that COVID-19 patients have higher prevalence of cotton wool spots (ES = 0.06; 95% CI, 0.03-0.09), retinal hemorrhages (ES = 0.12; 95% CI, 0.06-0.18), and retinal vein tortuosity (ES = 0.19; 95% CI, 0.09-0.35).

COVID-19 can exhibit extrapulmonary manifestations, affecting both the anterior and posterior segments of the eye. Common anterior-segment findings include conjunctivitis, whereas posterior-segment findings may include cotton wool spots, retinal hemorrhages, and retinal vein tortuosity. Improving our understanding of the ocular manifestations of COVID-19 has the potential to facilitate quicker diagnosis and subsequent treatment.

The COVID-19 pandemic was caused by severe acute respiratory syndrome coronavirus-2 (SARS-COV2). The impact of the pandemic is becoming more apparent now on various tissues and body organs. Limited knowledge is present about the characteristics, duration, and long-term sequelae of ocular problems post-COVID-19 infection. The purpose of the present study was to evaluate and analyze the ocular problems occurring in healthcare workers after COVID-19 infection.

This was a cross-sectional survey study conducted in the Department of Ophthalmology, Patna Medical College and Hospital, Patna. The participants were healthcare workers who were exposed to COVID-19 infection ≥6 months back. A questionnaire was prepared. Responses were evaluated and analyzed. Patient consent and institutional committee permission were taken as per norms.

A total of 210 healthcare workers who were infected with COVID-19 >6 months back responded with complete answers. The maximum number of respondents was between the ages of 31 and 60 (73.3%). The pre-covid ocular problems were present in 25% of the participants, especially in those having chronic diseases (such as diabetes, hypertension, or both). Post-ocular problems were faced by 60% of the participants, which was significant (P < 0.01). Dry eye, itching, and foreign body sensations were present in 60% of those facing ocular problems (P < 0.01). Ocular surface manifestations were more common.

A knowledge, understanding, and awareness about ocular problems and their long-term sequelae in post-COVID-19-infected patients will help in early diagnosis and better management of such patients.

Endogenous endophthalmitis (EE) is a rare but severe intraocular infection resulting from hematogenous dissemination of microorganisms. During the COVID-19 pandemic, there has been a notable increase in EE cases. This literature review aims to evaluate studies focusing on EE associated with COVID-19 to elucidate its pathogenesis and optimize patient management strategies. A thorough search was conducted across PubMed, ScienceDirect, and Google Scholar for relevant research. The surge in EE cases during the COVID-19 pandemic is likely linked to alterations in immune status and systemic comorbidities exacerbated by the virus and its treatments. Notably, Candida albicans and Aspergillus species emerged as the predominant fungal pathogens in these cases. The findings suggest that the increased incidence of EE is associated with immune dysregulation and increased vulnerability of COVID-19 patients, particularly those with severe diseases or undergoing immunosuppressive treatments. Early diagnosis with timely and effective treatment is crucial for improving patient outcomes. Regular ophthalmic evaluations for hospitalized COVID-19 patients are strongly advised to detect and address ocular complications early.

Observational studies have suggested that SARS-CoV-2 infection increases the risk of neurological diseases, but it remains unclear whether the association is causal. The present study aims to evaluate the causal relationships between SARS-CoV-2 infections and neurological diseases and analyzes the potential routes of SARS-CoV-2 entry at the cellular level. We performed Mendelian randomization (MR) analysis with CAUSE method to investigate causal relationship of SARS-CoV-2 infections with neurological diseases. Then, we conducted single-cell RNA sequencing (scRNA-seq) analysis to obtain evidence of potential neuroinvasion routes by measuring SARS-CoV-2 receptor expression in specific cell subtypes. Fast gene set enrichment analysis (fGSEA) was further performed to assess the pathogenesis of related diseases. The results showed that the COVID-19 is causally associated with manic (delta_elpd, - 0.1300, Z-score: - 2.4; P = 0.0082) and epilepsy (delta_elpd: - 2.20, Z-score: - 1.80; P = 0.038). However, no significant effects were observed for COVID-19 on other traits. Moreover, there are 23 cell subtypes identified through the scRNA-seq transcriptomics data of epilepsy, and SARS-CoV-2 receptor TTYH2 was found to be specifically expressed in oligodendrocyte and astrocyte cell subtypes. Furthermore, fGSEA analysis showed that the cell subtypes with receptor-specific expression was related to methylation of lysine 27 on histone H3 (H3K27ME3), neuronal system, aging brain, neurogenesis, and neuron projection. In summary, this study shows causal links between SARS-CoV-2 infections and neurological disorders such as epilepsy and manic, supported by MR and scRNA-seq analysis. These results should be considered in further studies and public health measures on COVID-19 and neurological diseases.

To investigate the prevalence, patterns, and predictors of SARS-CoV-2 RNA and culturable virus in tears of a case-ascertained household cohort.

Prospective, longitudinal case-ascertained household cohort identified through convenience sampling.

This analysis was restricted to individuals who were non-hospitalized, symptomatic, and tested positive for SARS-CoV-2 by nasal RT-PCR. Tears and anterior nasal biospecimens were serially collected throughout the acute period. Tears specimens were collected by the study staff using Schirmer test strips, and nasal specimens were self-collected. For both, SARS-CoV-2 RNA was quantified using qRT-PCR, and culturable virus was detected using presence of cytopathic effect (CPE) in tissue culture; positive CPE was confirmed by a qRT-PCR step. A series of cross-sectional unadjusted analyses were performed investigating the relationship between different sociodemographic determinants and biological factors associated with tears RNA positivity.

Among the 83 SARS-CoV-2 infected participants, 10 (12%) had at least one RNA-positive tears specimen. Amongst these 10, 5 (50%) had concurrent presence of culturable virus, at a median of 7 days postsymptom onset (IQR: 4-7 days) (absolute range: 4-8 days).

In this longitudinal cohort, we found evidence of culturable virus in the tears of a small proportion of nonhospitalized SARS-CoV-2 infected individuals. Current public health infection precautions do not account for transmission via tears, so these findings may improve our understanding of potential sources of SARS-CoV-2 transmission and contribute to developing future guidelines.

COVID-19 is still a major public health concern, mainly due to the persistence of symptoms or the appearance of new symptoms. To date, more than 200 symptoms of long COVID (LC) have been described. The present review describes and maps its relevant clinical characteristics, pathophysiology, epidemiology, and genetic and nongenetic risk factors. Given the currently available evidence on LC, we demonstrate that there are still gaps and controversies in the diagnosis, pathophysiology, epidemiology, and detection of prognostic and predictive factors, as well as the role of the viral strain and vaccination.

The aim of the study was to investigate the expression levels of ACE2 in ocular glands and to investigate the effect of S protein on them. Male C57BL/6J mice were used for the experiments. The expression levels of ACE2 are highest in the Meibomian glands, followed by the conjunctiva, the cornea, and the lacrimal glands. Co-immunoprecipitation assays confirmed direct binding between ACE2 and S protein in ocular surface epithelia and Meibomian glands. CD45+ cell infiltration was found in the S protein treatment group, which was accompanied by upregulation of inflammation-related cytokines. There was also prominent cell apoptosis in the S protein treatment group. In conclusion, not only the cornea and the conjunctiva, but also the Meibomian glands express ACE2, and S protein could induce ocular surface epithelial cell and Meibomian gland cell inflammation and apoptosis.

Several reports of suspected oral and ocular manifestations of coronavirus disease 2019 (COVID-19) has prompted investigations into ocular signs, symptoms, and transmission (5).11.2% of patients with COV19 infection had ocular symptoms, including ocular pain, conjunctivitis, dry eye, and floaters, meanwhile, many studies had documented oral symptoms such as dry mouth and dysgeusia in these patients. Our case reported a 39-year-old male, presented with symptoms of dry mouth and dry eye lasting more than 3 months. The patient had recovered from (PCR-confirmed) COVID-19 which lasted 10 days, 4 months ago. The physical examination was normal. Ocular findings include conjunctival hyperemia and superficial punctate keratitis. The anti-nuclear antibody (ANA) was weekly positive at 1/80. Schirmer test considered positive. He continued on 200 mg/day of hydroxychloroquine, along with tear drops until now with remission. Sicca symptoms may be a sequel of COVID-19 infection, and physicians should be aware of this sequel. The sequela of this infection is not understood, with limited data in the literature. Future prospective cohort studies are needed to reveal the impact of these features on oral health.

Early detection of the coronavirus is acknowledged as a crucial measure to mitigate the spread of the pandemic, facilitating timely isolation of infected individuals, and disrupting the transmission chain. In this study, we leveraged the properties of synthesized Ag-MOF, including high porosity and increased flow intensity. Electrochemical techniques such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed to develop an economical and portable sensor with exceptional selectivity for COVID-19 detection. The methodology involves the deposition of Ag-MOF onto the surface of a Glassy Carbon Electrode (GCE), which resulted in a progressive augmentation of electric current. Subsequently, the targeted antibodies were applied, and relevant tests were conducted. The sensor demonstrated the capacity to detect the virus within a linear range of 100 fM to 10 nM, boasting a noteworthy Limit of Detection (LOD) of 60 fM. The entire detection process could be completed in a brief duration of 20 min, exhibiting high levels of accuracy and precision, outperforming comparable techniques in terms of speed and efficacy.

(1) Background: to analyze the impact of the COVID-19 pandemic on the characteristics and management of uveal melanoma (UM) in the National Referral Center in Poland. (2) Materials and Methods: the retrospective analysis of 1336 patients who were newly diagnosed with UM at the Department of Ophthalmology and Ophthalmic Oncology, Jagiellonian University Collegium Medicum Krakow, Poland between 1 January 2018 and 31 December 2021. The demographic and clinical data were compiled, including localization, size, and treatment methods of tumors. (3) Results: In total, 728 patients with UM were included before the COVID-19 pandemic, in the years 2018-2019, and 608 were included during the COVID-19 pandemic, in the years 2020-2021. Fixed-base dynamics indicators for the incidence of uveal melanoma (base year 2018) in the National Referral Center in Poland were 80.22% and 86.81% in the years 2020 and 2021, respectively. UMs were statistically significantly larger and more frequently localized anterior to the equator of the eye globe in the year 2021 than in the year 2018 (Chi-square Pearson test p = 0.0001 and p = 0.0077, respectively). The rate of patients treated with enucleation increased from 15.94% in the year 2018 to 26.90% in the year 2021 (Chi-square Pearson test p = 0.0005). (4) Conclusions: Statistically significant differences were found in the management of uveal melanoma in the National Referral Center in Poland during the COVID-19 pandemic with tumors being larger, more frequently localized anterior to the equator of the eye globe, and more often enucleated.

The prone position reduces mortality in severe cases of COVID-19 with acute respiratory distress syndrome. However, visual loss and changes to the peripapillary retinal nerve fiber layer (p-RNFL) and the macular ganglion cell layer and inner plexiform layer (m-GCIPL) have occurred in patients undergoing surgery in the prone position. Moreover, COVID-19-related eye problems have been reported. This study compared the p-RNFL and m-GCIPL thicknesses of COVID-19 patients who were placed in the prone position with patients who were not. This prospective longitudinal and case-control study investigated 15 COVID-19 patients placed in the prone position (the "Prone Group"), 23 COVID-19 patients not in the prone position (the "Non-Prone Group"), and 23 healthy, non-COVID individuals without ocular disease or systemic conditions (the "Control Group"). The p-RNFL and m-GCIPL thicknesses of the COVID-19 patients were measured at 1, 3, and 6 months and compared within and between groups. The result showed that the Prone and Non-Prone Groups had no significant differences in their p-RNFL thicknesses at the 3 follow-ups. However, the m-GCIPL analysis revealed significant differences in the inferior sector of the Non-Prone Group between months 1 and 3 (mean difference, 0.74 μm; P = 0.009). The p-RNFL analysis showed a significantly greater thickness at 6 months for the superior sector of the Non-Prone Group (131.61 ± 12.08 μm) than for the Prone Group (118.87 ± 18.21 μm; P = 0.039). The m-GCIPL analysis revealed that the inferior sector was significantly thinner in the Non-Prone Group than in the Control Group (at 1 month 80.57 ± 4.60 versus 83.87 ± 5.43 μm; P = 0.031 and at 6 months 80.48 ± 3.96 versus 83.87 ± 5.43 μm; P = 0.044). In conclusion, the prone position in COVID-19 patients can lead to early loss of p-RNFL thickness due to rising intraocular pressure, which is independent of the timing of prone positioning. Consequently, there is no increase in COVID-19 patients' morbidity burden.

Ophthalmic manifestations have recently been observed in acute and post-acute complications of COVID-19 caused by SARS-CoV-2 infection. Our precious study has shown that host RNA editing is linked to RNA viral infection, yet ocular adenosine to inosine (A-to-I) RNA editing during SARS-CoV-2 infection remains uninvestigated in COVID-19. Herein we used an epitranscriptomic pipeline to analyze 37 samples and investigate A-to-I editing associated with SARS-CoV-2 infection, in five ocular tissue types including the conjunctiva, limbus, cornea, sclera, and retinal organoids. Our results revealed dramatically altered A-to-I RNA editing across the five ocular tissues. Notably, the transcriptome-wide average level of RNA editing was increased in the cornea but generally decreased in the other four ocular tissues. Functional enrichment analysis showed that differential RNA editing (DRE) was mainly in genes related to ubiquitin-dependent protein catabolic process, transcriptional regulation, and RNA splicing. In addition to tissue-specific RNA editing found in each tissue, common RNA editing was observed across different tissues, especially in the innate antiviral immune gene MAVS and the E3 ubiquitin-protein ligase MDM2. Analysis in retinal organoids further revealed highly dynamic RNA editing alterations over time during SARS-CoV-2 infection. Our study thus suggested the potential role played by RNA editing in ophthalmic manifestations of COVID-19, and highlighted its potential transcriptome impact, especially on innate immunity.

Numerous neurological manifestations associated with COVID-19 have been reported. However, abducens nerve palsy (ANP) associated with COVID-19 is very rare and mostly related to accompanying respiratory symptoms. Here we present a 29-year-old woman with unilateral ANP manifesting with diplopia and positive SARS-CoV-2 S antibodies, which were checked later. On admission, she had signs of viral pneumonia in thorax CT without any respiratory symptoms. Her cranial neuroimaging revealed no abnormality. Following treatment with favipiravir 2x1600 mg loading dose and then 2x600mg daily maintenance, dexamethasone 8 mg/day and enoxaparin 6000 IU/day, her CT findings recovered completely whereas her ANP only partially resolved. One week after the end of COVID-19 treatment, she also developed Herpes simplex keratitis which was successfully treated with valacyclovir. It should be kept in mind that isolated abducens nerve palsy may be the only finding of COVID-19 cases without any respiratory symptoms.

To investigate oculoplastic conditions in patients diagnosed with coronavirus disease 2019 (COVID-19) seen at ophthalmology departments of three tertiary referral centers in the United Kingdom and the United States, and review of the literature.

Retrospective multicenter case series studied over 18 months.

A total of four patients developed eyelid, orbital, or lacrimal gland pathology within four weeks of testing positive for COVID-19. All were male, and the mean age at presentation was 49 (range, 31-58 years). Suspected diagnoses included anterior idiopathic orbital inflammation, facial angioedema, dacryoadenitis, and anophthalmic socket inflammation. Three patients recovered fully and one patient recovered partially (mean 2.7 weeks) from ocular manifestations with steroids hastening recovery.

Adnexal manifestations of COVID-19 include self-limiting orbital inflammation and eyelid lymphedema.

To evaluate the possibility of coronavirus disease 2019 (COVID-19) transmission through the eyes, particularly through the ocular surface and conjunctival route, as well as the positivity of conjunctival swab test.

A narrative review was conducted to assess the possibility of COVID-19 transmission and the role of conjunctival swabs in diagnosing COVID-19 patients. Several studies were analyzed to compare the positivity rates and sensitivities of conjunctival swabs versus nasopharyngeal swabs.

Despite the fact that respiratory droplets are the major route of severe acute respiratory syndrome coronavirus 2 transmission, the eyes can potentially serve as an active (via tears) or passive route (via the nasolacrimal duct) of infection. Besides, conjunctival swabs exhibited a low positive rate and sensitivity for detecting COVID-19 compared to nasopharyngeal swabs. While nasopharyngeal swabs typically showed positivity rates between 60% and 100%, conjunctival swabs ranged from showing no detectable evidence to a 57% positivity rate.

Despite the low transmission rate through the eyes, thorough consideration is necessary as ocular transmission cannot be entirely ruled out. Further research and vigilance are warranted to better understand and mitigate potential ocular routes of COVID-19 transmission.

Ocular involvement is not uncommon in patients with COVID-19. However, the incidence of COVID-19 ophthalmopathy in COVID-19 patients is still not clear. In this prospective case series study, we recruited 2445 consecutive cases presenting at Neuro-ophthalmology clinic of our Eye Center during the last resurgence of SARS-CoV-2 infection from 8 December 2022 to 15 March 2023 in China, 149 cases were diagnosed as COVID-19 ophthalmopathy, 87 cases were female, with a mean age of 43.2 years, and the mean follow-up time was 15.4 weeks. One hundred and twenty of 149 cases suffered from systemic symptoms mostly manifesting as fever, cough and muscle pain prior to or soon after ocular involvement. The most common COVID-19 ophthalmopathy was optic neuritis (51/149), followed by acute zonal occult outer retinopathy complex disease (31/149), uveitis (17/149), ocular mobility disorder-related (third, fourth, or sixth) cranial nerve neuritis (15/149), anterior ischaemic optic neuropathy (9/149), retinal artery occlusion (8/149), retinal microangiopathy including retinal haemorrhage and cotton wool spot (8/149), viral conjunctivitis (7/149), retinal vein occlusion (3/149), viral keratitis (2/149), ptosis (2/149), and other rare ocular diseases. Except 5 cases with central retinal artery occlusion, other 144 COVID-19 ophthalmopathy cases showed good response to steroid therapy. Our study revealed an incidence of 6.09% for COVID-19 ophthalmopathy in outpatients at our Neuro-ophthalmology clinic during last resurgence of COVID-19 in China, and demonstrated that SARS-CoV-2 infection could induce an initial onset or a relapse of ophthalmic diseases, and that ocular involvement might manifest as the initial or even the only presentation of COVID-19.

SARS-CoV-2 is known to infect respiratory tissue cells. However, less is known about infection of ocular tissue and potential infectivity of lacrimal fluid. With this study, we want to compare viral loads in eye and nasopharyngeal swabs and analyze these for infectious virus.

Between May 2020 and April 2021 ocular and nasopharyngeal swabs were collected from 28 SARS-CoV-2 infected patients treated on the corona virus disease 2019 (COVID-19)-ward of the University Hospital of Innsbruck, Austria. Samples with PCR detectable SARS-CoV-2 were analyzed via whole genome sequencing and an attempt was made to isolate infectious virus.

At the time point of sample collection, 22 individuals were still PCR positive in nasopharyngeal samples and in 6 of these patients one or both ocular samples were additionally positive. CT-values in eyes were generally higher compared to corresponding nasopharyngeal samples and we observed a tendency for lower CT-values, i.e. increased viral load, in nasopharyngeal swabs of individuals with at least one infected eye, compared to those where ocular samples were PCR negative. Ocular and nasopharyngeal sequences from the same patient were assigned to the same variant, either the D614G or the Alpha variant. Infectious virus was successfully isolated from 9 nasopharyngeal swabs, however only from one of the seven PCR positive ocular samples.

We could detect SARS-CoV-2 in eyes of some of the infected patients albeit at lower levels compared to nasopharyngeal swabs. However, our results also indicate that lacrimal fluid might be infectious in patients with high viral load.

Coronavirus disease 2019 is a disease caused by the novel severe acute respiratory syndrome coronavirus 2. The double-positive of angiotensin-converting enzyme 2 and transmembrane protease serine type 2 have a higher risk of being infected by severe acute respiratory syndrome coronavirus 2. The susceptibility of coronavirus disease 2019 in patients with chronic diseases, especially in different tissues of ocular hypertension eyes like glaucoma, is not yet known.

An ocular hypertension model was established by laser photocoagulation in rhesus monkeys. The expression of angiotensin-converting enzyme 2 and transmembrane protease serine type 2 in three ocular hypertension eyes and the three control eyes were analyzed using immunofluorescence.

No difference was observed between ocular hypertension and control eyes in the expression of angiotensin-converting enzyme 2 and transmembrane protease serine type 2 in the conjunctival epithelium, corneal epithelium, and ciliary muscle. In ocular hypertension eyes and control eyes, angiotensin-converting enzyme 2 and transmembrane protease serine type 2 expression were both observed in the retina. Angiotensin-converting enzyme 2 staining of retinal ganglion cells was found to be significantly higher in ocular hypertension eyes than in control eyes. However, there was no difference in angiotensin-converting enzyme 2 and transmembrane protease serine type 2 expression in retinal vessels and choroidal vessels between ocular hypertension and control eyes. In our study, the expression and distribution of angiotensin-converting enzyme 2 and TMPREE2 in human retina were similar to that of non-human primates as expected.

Our study confirmed that angiotensin-converting enzyme 2 and transmembrane protease serine type 2 were expressed widely in rhesus monkey eyes. When compared with controls eyes, the expression of angiotensin-converting enzyme 2 was higher in the retinal ganglion cells in ocular hypertension eyes, suggesting that high ocular pressure may affect the patients' ocular susceptibility to severe acute respiratory syndrome coronavirus 2 infection.

In this study, we aimed to detect changes in posterior segment structures and vascular density caused by COVID-19 using an optical coherence tomography angiography (OCTA) device.

The study included 20 eyes of 20 patients no systemic or ocular disease who were followed at the Ophthalmology Clinic of Health Sciences University Antalya Training and Research Hospital. The OCTA images of these individuals taken prior to contracting COVID-19 and six months after recovery were examined.

The mean choriocapillaris blood flow was 2.00±0.13mm2 before COVID-19 and 2.08±0.23mm2 after the disease, and the mean subfoveal choroidal thickness was 247.33±7.65μm before the disease and 273.08±4.92μm after the disease, indicating a statistically significant difference (P=0.003, P=0.001, respectively). The mean retinal nerve fiber layer thickness before and after COVID-19 were 119.33±3.88 and 117.50±3.92μm, respectively, representing a statistically significant decrease (P<0.001).

This is the first study in the literature to evaluate the post-COVID-19 changes in the vascular structures of the eye compared to the pre-disease values. In this study, we found statistically significant changes in choriocapillaris blood flow, subfoveal chroidal thickness and retinal nerve fiber layer thickness after COVID-19 infection. Further research with a greater sample size is needed to explore the effect of COVID-19 on these parameters.

The potential risks associated with organs from COVID-19-infected donors were unclear. To determine the SARS-CoV-2 infection status of corneas transplanted during the COVID-19 pandemic, we performed a polymerase chain reaction (PCR) using the corneal preservation solution that was used for corneal transplantation. We also examined the postoperative health status of the recipients. This study included 144 transplants in 143 eyes. Ninety-nine eyes of imported corneas and 10 of the 14 corneas donated in the prefecture were PCR tested at our hospital, and all were SARS-CoV-2 negative. All corneal transplants were performed after confirming their SARS-CoV-2 negativity by a PCR using a corneal preservation solution at our hospital or a nasopharyngeal swab at a previous facility. Despite postoperative steroid administration, no patient developed COVID-19 infection until discharge. Hence, if the donor's nasopharyngeal swab test is SARS-CoV-2 negative, COVID-19 infection in the recipient due to corneal transplantation may be prevented. Since corneal transplant recipients are susceptible to infection due to prolonged steroid administration and are at high risk for severe diseases if infection occurs, SARS-CoV-2 detection testing using nasopharyngeal swabs in donors should be performed.

To detect the viral RNA load of SARS-CoV-2 in conjunctival swabs of COVID-19 patients, and compare with nasopharyngeal swabs.

Conjunctival swabs of COVID-19 patients (with PCR positive nasopharyngeal swabs) were subjected to quantitative reverse transcription-polymerase chain reaction (RT-PCR) for detection of SARS-CoV-2 RNA. The cycle threshold (Ct) values of Open Reading Frame 1 (ORF 1 Ab gene) and nucleoprotein (N gene) PCRs were used to assess the viral RNA load, and compare them with the baseline values of nasopharyngeal swabs.

Of 93 patients, 17 (18.27%) demonstrated SARS-CoV-2 RNA in conjunctival swabs. Baseline nasopharyngeal swabs were collected at a median of 2 days; while, the conjunctival swabs were collected at median 7 days, from onset of illness (p < 0.001). Despite a significant delay in conjunctival swab collection than nasopharyngeal swabs, the Ct values (ORF or N gene PCRs) were comparable between nasopharyngeal swab and conjunctival swab samples. Subsequently, during the recovery period, in four of these 17 patients (with conjunctival swab positivity), when the second nasopharyngeal swab was 'negative', the conjunctival swab was 'positive'.

The conjunctival swabs demonstrated SARS-CoV-2 RNA in 17 (18.27%) of 93 COVID-19 patients. Our results may suggest a delayed or a prolonged shedding of the virus/viral RNA on the ocular surface than in nasopharyngeal mucosa.