Association of foveal avascular zone FAZ enlargement with SARS-CoV-2 infection and long COVID-19, 2025, Spielmann et al.

[SNT Gatchaman]

Association of foveal avascular zone FAZ enlargement with SARS-CoV-2 infection and long COVID-19

Spoiler: Authors

Spielmann, J; Pink, I; Framme, C; Tode, J; Volkmann, I

BACKGROUND
As COVID-19 was found to affect small vessels of multiple organ systems, the purpose of the study is to describe the macular vessel density (VD) and the area of the foveal avascular zone (FAZ) by optical coherence tomography angiography (OCTA) in patients who recovered from a COVID-19 disease, who were or were not treated in an Intensive Care Unit (ICU) and who suffer from fatigue due to long COVID.

METHODS
Prospective case-control study in which laboratory-confirmed and recovered COVID-19 patients were included. Macular OCTA was performed at least seven weeks after initial COVID-19. The VD of the superficial retinal capillary plexus (SCP) and the area of the FAZ were measured. Results were compared among ICU- and non-ICU COVID-19 patients and a healthy control group; moreover, patients were divided into groups of no fatigue, fatigue, and extreme fatigue and results were compared among these and a control group.

RESULTS
FAZ of non-ICU patients was significantly enlarged compared to control group. VD was not significantly different among these cohorts. FAZ of fatigue group was significantly enlarged compared to no fatigue group and control group. VD of extreme fatigue group was significantly greater than VD of both no fatigue group and control group.

CONCLUSION
The retinal microvasculature of recovered COVID-19 patients showed alterations in the sense of a significantly enlarged FAZ, particularly in patients with mild disease and fatigue. These microvascular manifestations may lead to future complications or visual impairment. Performing macular OCTA could be a possible monitoring tool for microvascular changes in these patients and a predictor for long COVID fatigue.

Web | DOI | PDF | BMC Ophthalmology | Open Access

 

[ScoutB]

Oh! This is potentially pretty significant right?

Let me know if this is correct: because the eyes share a blood supply with the brain, we might be able to infer what's going on with capillaries in the brain by looking at the (more accessible) capillaries of the eye? I think I've heard of this in the context of like alzheimer's research or something.

Google is telling me an enlarged foveal avascular zone "is typically caused by retinal ischemia (poor blood flow)" so that seems like it would line up with the theories about problems with cerebral blood flow.

Maybe the paper already mentions all this, will check it out properly when less foggy.

 

[SNT Gatchaman]

Let me know if this is correct: because the eyes share a blood supply with the brain, we might be able to infer what's going on with capillaries in the brain by looking at the (more accessible) capillaries of the eye? I think I've heard of this in the context of like alzheimer's research or something.

Yes if "the eyes are the windows to the soul" then the retina are windows to the vasculature. Here's what the discussion said —

The OCTA technique, which we used to obtain our results, is an easy way to examine the microvascular status of subjects, as it is non-invasive, easy to handle and provides reliable and detailed information about retinal vessels. Though only retinal microvasculature can be seen, OCTA parameters may reflect the microvascular status of other organ systems, as well.

Particularly the microvascular status of other neuronal tissues can be evaluated in an easy way using OCTA, because the retinal and cerebral microvasculature show an anatomical and physiological homology. This is especially relevant as there are currently no clinical applicable imaging methods that allow for direct, non-invasive measurement of cerebral microvasculature.

 

[SNT Gatchaman]

Google is telling me an enlarged foveal avascular zone "is typically caused by retinal ischemia (poor blood flow)"

Yes, the fovea is for sharp, central vision, where retinal capillaries would be in the way. See Wikipedia.

Unlike in other tissues, retinal plexi do not form anastomoses, but are composed of end arteries. So, the FAZ boundaries are formed by such end arteries, which might cause particular susceptibility for ischemia and could in conclusion be a possible explanation for the seen alterations of FAZ.

Our results show the increased FAZ only for the patients with fatigue, but not for those with extreme fatigue. This may be due to the small number of patients with extreme fatigue (n = 12 eyes), which may have prevented statistical significance of a possible effect. Nevertheless, the tendency of an increased FAZ is also present in this cohort.

Contrary to what would be expected, our study shows a significantly greater VD [vessel density] in the patients with extreme fatigue compared to the patients with no fatigue and to the control group. A result to be expected would be an increased FAZ correlating with a decreased VD; also, in the study of Schlick et al. a decreased VD was found for different subgroups of post COVID-19 syndrome patients, but no increased VD for any subgroup. Pathophysiologically, no conclusive explanation can be found for that increased VD, so that it must also be discussed whether this is due to the small number of cases in the group of patients with extreme fatigue and could be seen as a statistical outlier.