Pfizer COVID-19 Vaccine May Cause Subtle Eye Changes, Study Finds

A recent study published in *Ophthalmic Epidemiology* has raised concerns over potential effects of the Pfizer-BioNTech COVID-19 vaccine on the eye’s cornea. Conducted by researchers in Turkey, the study found measurable changes in the corneal endothelium—the thin, innermost layer of the cornea responsible for keeping it clear—after vaccination.

Researchers observed 64 participants and measured their corneal health before the first vaccine dose and again around 75 days after the second. Findings showed that the corneas became slightly thicker and the density of endothelial cells dropped by approximately eight percent, from 2,597 to 2,378 cells per square millimeter. Additionally, the cells showed increased size variability and a small decrease in the percentage of cells retaining their normal hexagonal shape—changes that may indicate stress to the corneal tissue.

Though no participants reported noticeable vision problems, the researchers cautioned that these changes could pose a future risk, especially for individuals with pre-existing eye conditions or those who have undergone corneal transplants. If the changes persist over time, the study warns they could lead to corneal swelling or vision disturbances.

The team used specular microscopy, a technique for imaging the corneal endothelium, along with other diagnostic tools to rule out alternative causes and assess overall eye health. They also found a slight increase in the coefficient of variation—a marker of cell size irregularity—and a minor drop in the proportion of healthy hexagonal cells, both signs pointing to early endothelial stress.

While the authors did not advise against vaccination, they recommended close monitoring of patients with a history of eye surgery or low endothelial cell counts. “The endothelium should be closely monitored in those with a low endothelial count or who have had a corneal graft,” the study concluded.

The findings arrive amid broader scrutiny of COVID-19 vaccine side effects. In May, the U.S. Food and Drug Administration updated its guidance to include a warning about heart inflammation risks in young men following Pfizer and Moderna vaccinations.

Researchers emphasized the need for longer-term studies to determine whether the observed eye changes are temporary or lasting. In the meantime, they advise individuals with existing eye health concerns to consult an ophthalmologist before vaccination.