RNA-Seq Analysis Reveals an Essential Role of the Tyrosine Metabolic Pathway and Inflammation in Myopia-Induced Retinal Degeneration in Guinea Pigs.

Myopia is the second leading cause of visual impairment globally. Myopia can induce sight-threatening retinal degeneration and the underlying mechanism remains poorly defined. We generated a model of myopia-induced early-stage retinal degeneration in guinea pigs and investigated the mechanism of action. Methods: The form-deprivation-induced myopia (FDM) was induced in the right eyes of 2~3-week-old guinea pigs using a translucent balloon for 15 weeks. The left eye remained untreated and served as a self-control. Another group of untreated age-matched animals was used as naïve controls. The refractive error and ocular biometrics were measured at 3, 7, 9, 12 and 15 weeks post-FDM induction. Visual function was evaluated by electroretinography. Retinal neurons and synaptic structures were examined by confocal microscopy of immunolabelled retinal sections. The total RNAs were extracted from the retinas and processed for RNA sequencing analysis. Results: The FDM eyes presented a progressive axial length elongation and refractive error development. After 15 weeks of intervention, the average refractive power was -3.40 ± 1.85 D in the FDM eyes, +2.94 ± 0.59 D and +2.69 ± 0.56 D in the self-control and naïve control eyes, respectively. The a-wave amplitude was significantly lower in FDM eyes and these eyes had a significantly lower number of rods, secretagogin+ bipolar cells, and GABAergic amacrine cells in selected retinal areas. RNA-seq analysis showed that 288 genes were upregulated and 119 genes were downregulated in FDM retinas compared to naïve control retinas. In addition, 152 genes were upregulated and 12 were downregulated in FDM retinas compared to self-control retinas. The KEGG enrichment analysis showed that tyrosine metabolism, ABC transporters and inflammatory pathways were upregulated, whereas tight junction, lipid and glycosaminoglycan biosynthesis were downregulated in FDM eyes. Conclusions: The long-term (15-week) FDM in the guinea pig models induced an early-stage retinal degeneration. The dysregulation of the tyrosine metabolism and inflammatory pathways may contribute to the pathogenesis of myopia-induced retinal degeneration.

Retinal vessels modifications in acute and post-COVID-19.

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by SARS-CoV-2 primarily affecting the respiratory system which can damage vessels walls virtually in any body district. Changes affecting retinal vessels are a good marker for systemic vascular alterations. This study investigated retinal vessels during the acute phase of COVID-19 and after patients recovery. Fifty-nine eyes from 32 COVID-19 patients and 80 eyes from 53 unexposed subjects were included. Mean arteries diameter (MAD) and mean veins diameter (MVD) were assessed through semi-automatic analysis on fundus color photos at baseline and 6 months later in patients and subjects unexposed to the virus. At baseline MAD and MVD were significantly higher in COVID-19 patients compared to unexposed subjects (p < 0.0001). Both MAD and MVD significantly decreased in COVID-19 patients at follow-up (from 97.5 ± 10.9 to 92.2 ± 11.4 µm, p < 0.0001 and from 133.1 ± 19.3 to 124.6 ± 16.1 µm, p < 0.0001, respectively). Despite this reduction vessels diameter remained significantly higher in severe COVID-19 patients compared to unexposed subjects. Transient retinal vessels dilation could serve a biomarker for systemic inflammation while long-lasting alterations seen in severe COVID-19 likely reflect irreversible structural damage to the vessels walls and should be further investigated for their possible effects on tissues perfusion and function.

Severe COVID-19 and Retina: Are There Any Retinal Manifestations?

PURPOSE: To investigate whether there are retinal lesions associated with severe COVID-19. METHODS: We studied 232 symptomatic subjects aged 18 - 65 years who had severe COVID-19 and had received treatment. The evaluations included ophthalmological examinations, optical coherence tomography (OCT), imaging modalities with near infrared reflectance (NIR), fundus autofluorescence (FAF), and fundus photography (FP). RESULTS: The mean age of the patients was 49 years, and 67.6% of them were men. There were no findings of microhemorrhage, cotton wool spots (CWS), vitritis, or retinitis in the examination and imaging. CONCLUSIONS: This study indicates that retinal involvement as a complication associated with COVID-19 is questionable, although some reports have demonstrated a relationship that may occur secondary to existing systemic diseases.

Severe acute respiratory Syndrome-Coronavirus-2: Can it be detected in the retina?

BACKGROUND/OBJECTIVES: The systemic organ involvement of SARS-CoV-2 needs to be thoroughly investigated including the possibility of an ocular reservoir in humans. To examine retinal tissues and vitreous for histopathology and SARS-CoV-2 presence with regard to possible effects on the human retina and/ or vitreous. We performed histopathological analyses and quantitative (q)RT-PCR-testing for SARS-CoV-2 RNA on retinal tissues and vitreous of COVID-19 postmortem donors. SUBJECTS/METHODS: Included in this study were 10 eyes of 5 deceased COVID-19 patients. The diagnosis of SARS-CoV-2 infection was confirmed via pharyngeal swabs and broncho-alveolar fluids. The highest level of personal protective equipment (PPE) and measures was employed during fluid-tissue procurement and preparation. Histopathological examinations and qRT-PCR-testing were carried out for all retinal tissues and vitreous fluids. RESULTS: The histopathological examinations revealed no signs of morphologically identifiable retinal inflammation or vessel occlusions based on hematoxylin and eosin stains. By qRT-PCRs, we detected no significant level of viral RNA in human retina and vitreous. CONCLUSIONS: In this study, no significant level of SARS-CoV-2-RNA was detected in the human retinal and vitreous fluid samples of deceased COVID-19 patients. Histopathological examinations confirmed no morphological sign of damage to retinal vasculature or tissues. Further studies are needed to confirm or refute the results.

Coronavirus-19-Associated Retinopathy.

Background: To describe the first case of Coronavirus disease-2019 (COVID-19) vision loss from an acute outer retinopathy.Methods: A retrospective case report from a tertiary referral center using multimodal retinal imaging and clinical examination findingsFindings: A 40-year-old female developed significant vision loss in her right eye shortly after developing fever and myalgias. She was found to be COVID positive, while her systemic laboratory evaluation was otherwise unremarkable. Multimodal imaging was consistent with a white-dot-like outer retinopathy and she was started on systemic prednisone. Within 10 days of starting steroids, her vision, symptoms, and outer retinal changes on multimodal imaging were improving.Interpretation: While exceedingly rare, COVID-19 can cause inflammatory-associated changes of the outer retina and significant vision loss.

Acute Bilateral Neuroretinitis and Panuveitis in A Patient with Coronavirus Disease 2019: A Case Report.

Purpose: Herein, we report a case of bilateral neuroretinitis and panuveitis in a patient recovered from coronavirus disease 2019 (COVID-19).Case presentation: A 37-year-old male patient with a history of recovered COVID-19, which was confirmed with nasopharyngeal reverse transcriptase polymerase chain reaction (RT-PCR) for Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), about one-month ago was referred with one-week history of bilateral severe vision loss. Visual acuity was counting fingers, and bilateral retinitis and panuveitis were revealed in ocular examination. The result of the vitreous sample using RT-PCR was positive for SARS-CoV-2 and negative for Herpesviridae viruses and mycobacterium tuberculosis. The patient was successfully treated with corticosteroid.Conclusion: We report a case of bilateral neuroretinitis and panuveitisin a recovered COVID-19 patient and positive RT-PCR of the vitreous sample. It is suggested to apply intraocular sampling and evaluation for COVID-19 in patients with the new-onset of uveitis and/or retinitis during the pandemic.

Hypoxia-induced inflammation: Profiling the first 24-hour posthypoxic plasma and central nervous system changes.

Central nervous system and visual dysfunction is an unfortunate consequence of systemic hypoxia in the setting of cardiopulmonary disease, including infection with SARS-CoV-2, high-altitude cerebral edema and retinopathy and other conditions. Hypoxia-induced inflammatory signaling may lead to retinal inflammation, gliosis and visual disturbances. We investigated the consequences of systemic hypoxia using serial retinal optical coherence tomography and by assessing the earliest changes within 24h after hypoxia by measuring a proteomics panel of 39 cytokines, chemokines and growth factors in the plasma and retina, as well as using retinal histology. We induced severe systemic hypoxia in adult C57BL/6 mice using a hypoxia chamber (10% O2) for 1 week and rapidly assessed measurements within 1h compared with 18h after hypoxia. Optical coherence tomography revealed retinal tissue edema at 18h after hypoxia. Hierarchical clustering of plasma and retinal immune molecules revealed obvious segregation of the 1h posthypoxia group away from that of controls. One hour after hypoxia, there were 10 significantly increased molecules in plasma and 4 in retina. Interleukin-1ß and vascular endothelial growth factor were increased in both tissues. Concomitantly, there was significantly increased aquaporin-4, decreased Kir4.1, and increased gliosis in retinal histology. In summary, the immediate posthypoxic period is characterized by molecular changes consistent with systemic and retinal inflammation and retinal glial changes important in water transport, leading to tissue edema. This posthypoxic inflammation rapidly improves within 24h, consistent with the typically mild and transient visual disturbance in hypoxia, such as in high-altitude retinopathy. Given hypoxia increases risk of vision loss, more studies in at-risk patients, such as plasma immune profiling and in vivo retinal imaging, are needed in order to identify novel diagnostic or prognostic biomarkers of visual impairment in systemic hypoxia.

Retinal involvement and ocular findings in COVID-19 pneumonia patients.

Changes in immune and coagulation systems and possible viral spread through the blood-brain barrier have been described in SARS-CoV-2 infection. In this study, we evaluated the possible retinal involvement and ocular findings in severe COVID-19 pneumonia patients. A cross-sectional study was conducted on 46 patients affected by severe COVID-19 who were hospitalized in one intensive care unit (ICU) and in two infectious disease wards, including bedside eye screening, corneal sensitivity assessment and retinography. A total of 43 SARS-CoV-2-positive pneumonia patients affected with COVID-19 pneumonia were included, including 25 males and 18 females, with a median age of 70 years [IQR 59-78]. Except for one patient with unilateral posterior chorioretinitis of opportunistic origin, of whom aqueous tap was negative for SARS-CoV-2, no further retinal manifestation related to COVID-19 infection was found in our cohort. We found 3 patients (7%) with bilateral conjunctivitis in whom PCR analysis on conjunctival swabs provided negative results for SARS-CoV-2. No alterations in corneal sensitivity were found. We demonstrated the absence of retinal involvement in SARS-CoV-2 pneumonia patients. Ophthalmologic evaluation in COVID-19, particularly in patients hospitalized in an ICU setting, may be useful to reveal systemic co-infections by opportunistic pathogens.

Impending Central Retinal Vein Occlusion in a Patient with Coronavirus Disease 2019 (COVID-19).

PURPOSE: To report a case of impending central retinal vein occlusion (iCRVO) in a COVID-19 patient. CASE REPORT: A 54 years old woman with COVID-19 related pneumonia presented to our emergency department complaining of scotomas and decreased vision in her right eye. Funduscopic examination and multimodal imaging revealed rare retinal hemorrhages, retinal whitening, and fern-like hypo-autofluorescent appearance typical of iCRVO. She had no risk factors other than a transient hyper-coagulability status likely related to the ongoing infection. Systemic treatment with steroids normalized her inflammatory and coagulation status and the occlusion completely resolved. CONCLUSIONS: Retinal circulation should be considered as a potential site for thromboembolic complications from COVID-19.

COVID-19 retinal microangiopathy as an in vivo biomarker of systemic vascular disease?

IMPORTANCE: COVID-19 is caused by SARS-CoV-2, a betacoronavirus that uses the angiotensin-converting enzyme-related carboxypeptidase (ACE2) receptor to gain entry into cells. ACE2 receptor is widely expressed in multiple organs, including the retina, an extension of the central nervous system. The ACE2 receptor is involved in the diabetic and hypertensive retinopathy. Additionally, coronaviruses cause ocular infections in animals, including retinitis, and optic neuritis. OBJECTIVE: To assess whether there is any retinal disease associated with COVID-19. DESIGN: We have evaluated 27 asymptomatic subjects, with retinal fundoscopic, optical coherence tomography (OCT) and OCT angiography fourteen days after hospital discharge due to COVID-19 bilateral pneumonia. RESULTS: Cotton wool exudates were evident in six out of 27 patients evaluated, a 22%. Cotton wool exudates are a marker vascular disease severity in other medical context, that is diabetes and hypertension, and are associated with increased risk for acute vascular events. Whether antiaggregation therapy may play a role on fundoscopic-selected patients with COVID-19 requires prospective trials.

Chloroquine and Hydroxychloroquine Retinal Toxicity Consideration in the Treatment of COVID-19.

The proposed doses of chloroquine (CQ) and hydroxychloroquine (HCQ) for treatment of COVID-19 (1000 mg/day for 10 days, CQ; 800 mg first day then 400 mg/day for 5 days, HCQ) in many guidelines worldwide, are considerably higher than the maximum recommended daily safe doses of both agents (≤2.3 mg/kg/day, CQ; ≤5.0 mg/kg/day, HCQ) for development of retinal toxicity. Irreversible retinal damage can occur if the exposure to the safe doses is >5 years. It is not known whether exposure to high doses over a short period of time can also cause the damage. We recommend that before prescribing CQ or HCQ, history of ocular disease should be obtained to avoid the prescription if appropriate. If either agent is to be used, routine baseline ocular examination is not absolutely necessary. Patients who do not have ocular disease should also be informed about the potential risk of retinal toxicity. Both agents, however, have not yet been proven to be beneficial to COVID-19.