Change in retinal vessel diameter and choroidal thickness in patients with severe COVID-19: Change In Retinal Parameters In Patients With Severe COVID-19

Microvascular Changes during Viral Infections: A Systematic Review of Studies Using Retinal Vessel Diameter Assessments

Viral infection frequently affects the cardiovascular system, and vascular disturbances in patients can lead to health complications. One essential component of the cardiovascular system that is vulnerable to the inflammatory effects of viral infections is the microcirculatory system. As a suitable and practical non-invasive method to assess the structure and function of the retinal microcirculation, a proxy for the microcirculatory system, retinal fundus imaging can be used. We examined the impact of viral infections on retinal vessel diameters and performed a systematic analysis of the literature. Our search was carried out on PubMed using predefined search queries. After a methodological filtering process, we were able to reduce the corpus of 363 publications to 16 studies that met the search parameters. We used a narrative review style to summarise the observations. Six studies covered COVID-19, seven described HIV, and three were included in the subgroup called others, covering viruses, such as Dengue Fever and Crimean-Congo Haemorrhagic Fever. Analysis of the literature showed that viral infections are associated with alterations in the retinal vessels' vasoactivity. COVID-19 and other infections cause inflammation-associated the vasodilatation of microvasculature as a short-term effect of the infection. Long COVID-19 as well as HIV are the cause of chronic inflammation impacting microvascular morphology via retinal vessel diameter narrowing. The review emphasises the importance of the understudied area of viral infections' effects on retinal microcirculation. Continuous research in this area is needed to further verify retinal fundus imaging as an innovative tool for the optimal diagnosis of microvascular changes. As changes in the microvasculature precede changes in bigger arteries, the early detection of microvascular changes can go a long way in reducing the morbidity and mortality associated with cardiovascular diseases.

Relationship of the main indicators of systemic COVID-associated endotheliopathy with the morphofunctional state and hemodynamics of the retina and chorioid in the acute period of the disease

BACKGROUND: Nonspecific angio- and retinopathy is one of the clinical manifestations of a new coronavirus infection. The frequency of occurrence of these changes in people with severe COVID-19 does not exceed 55%. The causes, course and consequences of these microcirculatory disorders of the retina are currently not well understood. AIM: To study and compare of retinal morphometric parameters and systemic endothelial dysfunction markers, as well as the main clinical and laboratory parameters in patients with moderate and severe coronavirus infection during convalescence. MATERIALS AND METHODS: The study involved 44 patients (86 eyes) who had COVID-19 during the previous 3 months, who were divided into 2 groups: with moderate and severe disease. The control group consisted of 18 healthy volunteers (36 eyes). All patients underwent a standard ophthalmological examination and optical coherence tomography, which included an assessment of the choroidal thickness (CT) and measurement of the mean diameter of the peripapillary arteries (MAD) and veins (MVD). During hospitalization, all patients underwent a laboratory study of venous blood parameters, as well as an assessment of the microcirculation of the sublingual plexus by examining the density of the endothelial glycocalyx (PBR) using the GlycoCheck. RESULTS: In patients who underwent COVID-19, there was a significant increase in CT relative to the control group, amounting to 308, 344 and 392 m, respectively. The most pronounced difference was observed between MVD in patients with severe infection and the control group (119.1 m vs. 99.2 m). In patients with moderate and severe COVID-19, MAD and MVD were positively correlated with TC, with r = 0.389 and r = 0.584, respectively. MVD also correlated with the level of leukocytes (r = 0.504), the ESR value (r = 0.656). Correlations between MVD and data characterizing the state of the glycocalyx in the sublingual vascular plexus were revealed: the filling of small capillaries with erythrocytes (r = 0.587), as well as the marginal perfusion value in large capillaries 2025 m (r = 0.479) and PBR (r = 0.479). Only significant differences and correlations are shown (p 0.005). CONCLUSIONS: In patients who underwent moderate and severe COVID-19 during the convalescence period (up to 30 days), an increase in the diameter of peripapillary vessels and TC is observed, proportional to the severity of COVID-19, laboratory markers of systemic inflammation and hypercoagulation (the number of leukocytes, the ESR value, D-dimer and prothrombin), which indicates the inflammatory nature of the changes. The severity of postcovid retinal microangiopathy correlates with indicators detecting a decreasing of the endothelial glycocalyx thickness in the sublingual capillary plexus, which indirectly indicates a connection with systemic endotheliopathy.

The Effect of Corticosteroid Therapy on Choroidal Thickness in Patients With Covid-19 Infection: A Prospective, Comparative, and Observational Study

BACKGROUND

Coronavirus disease 2019 (Covid-19) has many different ocular manifestations. This study evaluates the effects of the disease and the steroid used in this disease on ocular structures.

PURPOSE

 To evaluate the effects of Covid-19 and the steroids used in the treatment of severe infection on ocular structures and choroidal thickness.

METHODS

This prospective study included 76 eyes of 76 patients who were hospitalized due to Covid-19 and 30 eyes of 30 healthy volunteering controls. Group I included 35 eyes who were hospitalized due to moderate-to-severe involvement that received steroid treatment, group II included 41 eyes with moderate involvement that did not require steroid treatment, and group III included 30 eyes with age- and gender-matched control subjects. Ophthalmological examination and imaging results of the patients obtained in the third week and third month after the diagnosis were compared between the groups.

RESULTS

Mean age of all participants was 40.2 ± 6.1 years. In the third week after the diagnosis of Covid-19, choroidal thickness in all regions (subfoveal, nasal, and temporal) was significantly greater in group I than in group II (for all, p<0.001). Moreover, choroidal thicknesses were significantly higher in group I and group II than in the control group (for all, p<0.001). In the third month, all the groups had similar choroidal thickness values (for subfoveal, nasal, and temporal; p=0.058, p=0.111, p=0.079, respectively).

CONCLUSION

Our findings showed that Covid-19 infection causes choroidal thickening by affecting the choroidal layer and that steroid treatment further increases this thickness in the acute period. In addition, the reversal of this thickening to the normal level within a period of three months indicates that the effect of the disease on the choroid is reversible.