Many people worried that COVID-19 might raise the risk of eye strokes. An eye stroke happens when a blood vessel in the retina gets blocked. The retina is the light-sensitive layer at the back of the eye. If blood cannot flow, vision can drop suddenly.
This fear was not baseless. COVID-19 can affect blood vessels and blood clotting. Some earlier reports suggested links to eye problems. But a new look at real-world data tells a different story.
During the first year of the pandemic, one leading eye hospital saw no clear rise in these events. That finding matters because it helps doctors and patients focus on proven risks and care.
Retinal vein and artery occlusions are not rare. They often happen in people with high blood pressure, diabetes, high cholesterol, or heart disease. They can cause sudden, painless vision loss. Many patients want to know if the pandemic added to their risk.
Current treatment focuses on the underlying condition and, in some cases, procedures to lower pressure in the eye. But prevention and early detection remain key. That is why tracking real-world trends is so important.
Before this study, some experts worried that COVID-19 infections might trigger more blockages. The idea is that the virus can inflame blood vessels and make clots more likely. That concern made sense.
But here’s the twist: large patterns in this hospital’s data did not show that surge. The numbers stayed close to what doctors saw before the pandemic.
Think of the eye’s blood vessels like a city’s road network. A blockage can cause a traffic jam that starves nearby areas. COVID-19 might act like road construction and bad weather at the same time. Yet this study found no extra pile-up on the eye’s roads during the first year.
The researchers looked at four types of events. Central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO) are blockages in the eye’s veins. Central retinal artery occlusion (CRAO) and branch retinal artery occlusion (BRAO) are blockages in the eye’s arteries. All can harm vision quickly.
The study took place at Jules-Gonin Eye Hospital in Lausanne, Switzerland. It compared new cases in 2019 with new cases in 2020. It also checked monthly patterns against local COVID-19 case counts.
The team used official population data to calculate rates. They looked for any link between rising COVID cases and rising eye events. The study period largely reflects natural infection, since vaccines in Switzerland began only at the very end of 2020.
In 2019, doctors recorded 66 retinal vein occlusions and 20 arterial occlusions. In 2020, they recorded 49 retinal vein occlusions and 21 arterial occlusions. On the surface, vein occlusions went down and arterial occlusions stayed similar.
The key question is whether these changes were meaningful after accounting for population size. The researchers calculated incidence rate ratios. For vein occlusions, the rate in 2020 was about 73% of the 2019 rate. The confidence interval ranged from 51% to 105%, and the p-value was .093. That means the drop could be due to chance.
For arterial occlusions, the rate in 2020 was about 104% of the 2019 rate. The confidence interval ranged from 57% to 190%, and the p-value was .896. That means there was no clear change.
The monthly analysis also found no significant link between COVID-19 case counts and these eye events. The p-value was .08, which is close but still not statistically significant.
This does not mean COVID-19 has no effect on the eye in any person.
Experts note that biologically plausible mechanisms still exist. Inflammation and clotting changes can occur in some patients. But at the population level in this region, the data did not show a clear rise.
What does this mean for you? If you have diabetes, high blood pressure, or a history of eye disease, keep up with regular eye exams. Sudden, painless vision loss needs urgent care. Talk with your doctor about your overall cardiovascular risk.
The study has limitations. It comes from one hospital in one region. The sample size is modest, so small effects could be missed. The study also ended before widespread vaccination, so it cannot speak to vaccine-era trends.
What happens next? Researchers will keep watching for changes in eye vascular events as the pandemic evolves. Larger, multi-center studies can help confirm these patterns. For now, this regional data offers reassurance that early pandemic trends did not show a spike in eye strokes.