By Chantelle Muanenhamo
A recent study by Turkish researchers has raised new concerns about potential side effects of the Pfizer-BioNTech COVID-19 vaccine, pointing to minor but measurable changes in the eyes specifically the cornea, the transparent front part that plays a vital role in focusing vision.
The peer-reviewed study monitored 64 individuals before and two months after receiving two doses of the Pfizer vaccine. While no participants reported visual problems, imaging tools revealed an average 2% increase in corneal thickness and a notable 8% drop in endothelial cell count, the specialized cells that help maintain corneal clarity by regulating fluid balance.
“In healthy individuals, these changes may not be clinically significant,” the researchers wrote. “But for people with pre-existing eye conditions or previous corneal transplants, the findings could signal a need for closer monitoring.”
Key Findings:
- Corneal thickness increased from 528 to 542 micrometres (a 2% rise)
- Endothelial cell density dropped from an average of 2,597 to 2,378 cells/mm² (an 8% decrease)
- Cell shape irregularities were observed, with fewer cells retaining their normal hexagonal form, a sign that may indicate inflammation or cellular stress
Though the endothelial cell counts remained within normal limits, experts caution that individuals with already low counts due to age, surgery, or conditions like Fuchs’ dystrophy could be more vulnerable to long-term effects. Loss of these cells beyond a certain threshold may lead to complications such as corneal edema or bullous keratopathy, both of which can impair vision or cause lasting damage.
Importantly, the researchers did not recommend avoiding the Pfizer vaccine. They emphasized that the study’s findings are preliminary and based on a short-term observation period. No participants experienced visual disturbances during the study, and further long-term studies are needed to determine if the effects persist or worsen over time.
This study adds to a growing body of research examining the rare but possible side effects of mRNA vaccines. In May, the U.S. Food and Drug Administration (FDA) updated warning labels on Pfizer and Moderna vaccines to include risks of myocarditis and pericarditis, particularly in younger males.
Still, scientists stress that the benefits of vaccination outweigh the risks for the vast majority of people, especially given the ongoing threat of COVID-19 variants.
“Our findings are not meant to fuel vaccine hesitancy,” the researchers concluded.
“Rather, they highlight the importance of continued post-vaccine surveillance, especially for individuals with underlying health conditions.”
As global vaccination efforts continue, medical professionals urge those with existing eye health issues especially corneal transplant recipients to consult their ophthalmologists if they experience changes in vision following vaccination.