Scientists have reported new findings suggesting that the Pfizer COVID-19 vaccine may cause short-term changes in the cornea, the clear front surface of the eye. A research team in Turkey followed 64 adults before their first dose and again about two months after their second shot. They wanted to see whether the vaccine affected the eye’s inner cell layer, known as the endothelium.

The study showed a small increase in corneal thickness and a decline in endothelial cell density. These cells keep the cornea clear by pumping out extra fluid. The counts stayed within the normal range for most people, but the change may matter for those with existing eye problems, such as Fuchs’ dystrophy, past eye surgery, or a corneal transplant. The researchers also noticed that the cells varied more in size and shape after vaccination, which can be a sign of temporary stress.

No participant reported vision loss or serious symptoms. Thickening of the cornea can happen during mild inflammation or irritation, and it often returns to normal. The concern would grow only if these changes continue for months or years. More long-term follow-up is needed to understand the full impact.

The researchers did not advise against vaccination. Instead, they encouraged people with known eye conditions to continue routine eye checks. An eye doctor can measure corneal health with specular microscopy. The team also noted that the benefits of COVID-19 vaccination remain strong, even as new data develops on rare side effects, including the previously identified risk of heart inflammation in some younger men.