Ocular Manifestations of COVID-19 Infection

COVID-19 infection has been linked to diverse ocular presentations ranging from transient conjunctivitis to deeper posterior segment changes. Reports describe retinal microvascular alterations, including reduced capillary density and transient vessel dilatation, as well as inflammatory and neuroglial responses within the retina. Severe systemic infection may precipitate microthrombosis, leading to retinal nerve fibre layer (RNFL) thinning, capillary non-perfusion and tissue loss detectable by advanced imaging. Histopathological analyses of donor eyes reveal activation of microglia, disruption of Müller cell architecture and cone photoreceptor degeneration, implicating hypoxia and inflammatory mediators in neuronal damage. Longer-term follow-up suggests that some vascular changes may partially reverse, while others, particularly following intensive care admission, persist as potential biomarkers of disease severity. The global scope of these findings underscores the eye as a window to systemic vascular health and highlights the need for ophthalmic surveillance in COVID-19 recovery and long COVID clinics.

Research from Nature Portfolio

A cross-sectional study analysed retinal imaging in control, mild and severe COVID-19 cohorts using spectral-domain optical coherence tomography and OCT angiography. Patients recovering from severe infection exhibited significantly lower total vessel density and reduced capillary plexus integrity in the macula compared with both healthy controls and those with milder disease. Corresponding decreases in retinal volume in the outer macular region reflected tissue loss beyond acute illness. These microvascular and structural deficits persisted weeks after discharge, suggesting permanent capillary damage as a potential marker of severe systemic involvement.

Ocular Manifestations of COVID-19 Infection publication trend

The graph below shows the total number of articles in ocular manifestations of covid-19 infection across all publications each year (not limited to Nature Index journals).

Technical terms

Optical coherence tomography (OCT): A non-invasive imaging modality that produces high-resolution cross-sectional images of retinal layers.

Optical coherence tomography angiography (OCTA): An extension of OCT that visualises blood flow within retinal and choroidal capillary plexuses without dye injection.

Retinal nerve fibre layer (RNFL): The innermost layer of the retina comprising axons of retinal ganglion cells.

Microglia: Resident immune cells of the central nervous system, including the retina, that mediate neuroinflammatory responses.

Müller cells: Principal glial cells spanning the full thickness of the retina, responsible for metabolic support and maintenance of retinal homeostasis.

References

1. New findings on retinal microvascular changes in patients with primary COVID-19 infection: a longitudinal study. Frontiers in Immunology (2024).
2. The Comparison of Retinal Microvascular Findings in Acute COVID-19 and 1-Year after Hospital Discharge Assessed with Multimodal Imaging—A Prospective Longitudinal Cohort Study. International Journal of Molecular Sciences (2023).
3. Microglia activation and neuronal alterations in retinas from COVID-19 patients: correlation with clinical parameters. Eye and Vision (2023).
4. Retinal tissue and microvasculature loss in COVID-19 infection. Scientific Reports (2023).