(Web Desk) – Scientists have discovered that Pfizer’s COVID-19 vaccine may increase the risk of eye damage, leading to vision loss.
The new study specifically examined how the vaccine affected patients’ corneas, the clear front part of the eye that allows light to enter.
In 64 people, scientists in Turkey measured changes in the cornea’s inner layer, called the endothelium, before taking the first Pfizer dose and two months after receiving the second.
Results revealed that taking both doses of the vaccine led to thicker corneas, fewer endothelial cells in the eye and more variation in size of these specialized cells that form the endothelium.
In the short term, these changes suggest the Pfizer vaccine may temporarily weaken the endothelium, even though patients didn’t suffer clear vision problems during the study.
For people with healthy eyes, these small changes likely won’t affect vision right away.
However, if scientists find that these changes last for years, they could lead to corneal swelling or blurry vision, especially in those with pre-existing eye problems or people who have had a cornea transplant.
A thicker cornea and reduced cell density could contribute to eye conditions like corneal edema, bullous keratopathy, or corneal decompensation, which can all cause permanent vision loss in severe cases, especially if left untreated.
The researchers warned in the study, published Wednesday in the journal Ophthalmic Epidemiology: ‘The endothelium should be closely monitored in those with a low endothelial count or who have had a corneal graft.’
An eye doctor can use a special microscope called specular microscopy to find out if someone has a low endothelial cell count.
If you have blurry vision or eye discomfort, this test can also check if your cornea’s cells are healthy.
A low count can be the result of aging, eye diseases like Fuchs’ dystrophy, eye surgeries, injuries, or infections. These factors damage the cells that keep your cornea clear, and they don’t grow back.
Specifically, the team found that the Pfizer-BioNTech vaccine caused a patient’s cornea to go from 528 to 542 micrometers in thickness, or roughly 0.0208 inches to 0.0213 inches. This is a roughly two-percent increase in micrometers.
A slightly thicker cornea isn’t automatically harmful. The cornea can thicken temporarily due to inflammation, fluid buildup, or stress on the endothelium from minor illnesses or injuries to the eyes.
If it stays too thick for months or years, however, it could make the cornea less clear, potentially affecting vision.
The team did not recommend against vaccination and will still need to conduct long-term testing on patients to see if these changes continue to appear months and years after taking the shots.
The average number of endothelial cells, which keep the cornea clear by pumping out excess fluid, dropped from 2,597 to 2,378 cells per square millimeter in the study, a loss of about eight percent.
Normal endothelial cell counts range from 2,000 to 3,000 cells per square millimeter in healthy adults, so 2,378 is still within a safe range for most people.
However, for someone with a low cell count to start with, due to a previous eye surgery, infection, or disease, this loss could be riskier for their vision.
Researchers also discovered that these cells became less uniform after the vaccination, with their coefficient of variation – each cell’s difference in size – increasing from 39 to 42.
When cells die, nearby cells stretch to fill the gaps, leading to bigger differences in size.
This could mean the endothelium is less healthy. If this trend continued for years, it could affect the cornea’s clarity.
After vaccination, the study found fewer cells kept their healthy six-sided shape, with the total dropping from 50 to 48 percent of the cells in the eye.
Healthy endothelial cells are usually shaped like hexagons, which allows them to fit together tightly, like a honeycomb.
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