A Turkish study reports a potential, short-term change in the cornea following Pfizer-BioNTech vaccination. Researchers observed small increases in corneal thickness and a decline in endothelial cell density after vaccination, but the changes were temporary and did not visibly affect vision in study participants.
The study tracked 64 adults who received the Pfizer vaccine, with imaging before the first dose and about two months after the second dose. The corneal endothelium kept the eye clear and showed an average thickness rise from 528 to 542 micrometers, about 2 percent, while endothelial cell density fell from roughly 2,597 to 2,378 cells per square millimeter, an 8 percent drop. Cells also showed more size variation and fewer hexagonal shapes, indicating cellular stress.
For most healthy individuals, vision remained stable during the roughly 75 days following the second vaccination. While this adds to the understanding of potential vaccine effects, global health authorities reiterate that vaccination benefits far outweigh these minor, short-term changes. Earlier warnings about rare myocarditis and pericarditis, especially in young men, have been noted by international health agencies and reflected in vaccine guidance.
What this means for Thailand Thailand’s large population received Pfizer and other mRNA vaccines during the pandemic. With rising rates of chronic conditions such as diabetes and hypertension—factors that can influence eye health—awareness of possible ocular side effects is important. Thai health authorities, including the Ministry of Public Health and the Thai Ophthalmological Society, monitor post-vaccination effects and may adjust guidance for individuals with known eye vulnerabilities.
Experts urge cautious interpretation rather than alarm. A senior researcher from the Turkish study calls for careful monitoring of the corneal endothelium in people with low counts or those who have had corneal grafts. Thai ophthalmologists note the endothelium is most at risk among older adults or those with prior eye surgery, Fuchs’ dystrophy, or corneal transplantation. Although observed changes often stay within normal ranges for healthy adults, added stress on compromised eyes could, over time, lead to issues such as corneal edema or decompensation.
Current guidance supports ongoing vaccination, with a practical emphasis on targeted eye care. If you have a history of corneal surgery or low endothelial cell counts, tell your eye doctor about recent vaccination. Seek an eye exam promptly if you notice blurry vision or eye discomfort after vaccination. A non-invasive specular microscopy test, widely available at major Thai eye centers, can assess corneal endothelium health.
Context and interpretation The reported micro-changes may reflect transient inflammation or cellular stress, patterns seen with other vaccines and illnesses. There is no evidence of permanent damage, and longer follow-up is needed to determine persistence or clinical impact. Age, prior eye disease, and surgical history are important factors in risk assessment.
Implications for Thai clinical practice As Thailand’s elderly population grows and cataract surgeries remain common, post-vaccination eye check-ups could become part of specialized eye care protocols, particularly for at-risk groups. Hospitals might consider including corneal health evaluations in post-vaccination follow-ups to catch evolving issues early.
Public health messaging Thai vaccine safety communications should balance openness with reassurance. Health authorities will continue to monitor eye-related side effects in collaboration with global partners. Messaging should promote vaccination while encouraging informed, proactive eye care, especially for individuals with pre-existing eye conditions or a history of eye surgery.
Practical next steps for readers
- If you have pre-existing eye disease or a history of corneal surgery, schedule a routine eye check-up a few months after any COVID-19 mRNA vaccination and report lasting vision changes.
- Maintain regular eye examinations for all, especially as screen time and chronic diseases rise in Thai society.
- Seek prompt eye evaluation if you experience blurry vision, discomfort, or vision changes after vaccination; specular microscopy can be used at major eye clinics.
Data and conclusions should be considered alongside ongoing global research. No changes to vaccine recommendations are advised at this time, but clinicians and patients should stay informed as new evidence emerges.