Could a simple vaccine shot quietly affect your eyesight? Scientists say one of the world’s most common COVID-19 vaccines may be doing just that.

A new Turkish study has found that Pfizer’s COVID-19 vaccine could cause subtle but measurable changes in the cornea — the clear front surface of the eye responsible for vision clarity. While the effects may seem minor at first, experts warn they could matter over time, especially for people already battling eye issues.

Researchers tracked 64 people before and after two Pfizer doses. Using specialized eye scans, they noticed thicker corneas and a loss of vital endothelial cells — the ones that keep the eye clear by pumping out excess fluid. “Even small drops in these cells can matter for long-term vision health,” the study’s authors explained.

Most participants didn’t notice any vision problems right away, but for those with previous eye surgeries, infections, or low cell counts, doctors say the risk may be higher. If these changes persist, they could lead to conditions like corneal swelling or blurriness.

Researchers stress the vaccine’s benefits still outweigh the risks — but call for continued monitoring. For millions who trusted these shots, the findings serve as a quiet reminder: even small changes in the body’s most delicate systems deserve a closer look.