A new Turkish study has raised concerns that Pfizer-BioNTech's COVID-19 vaccine may have subtle but serious side effects on the cornea. The research examined changes in the corneas of at least 64 patients before and after receiving both doses of the vaccine.
According to the scientists involved in the study published in the journal Ophthalmic Epidemiology, even though no immediate vision loss was reported, the vaccine led to thicker corneas, a reduced number of endothelial cells, and structural changes that could affect eye health over time.
The Daily Mail reported the changes in the eyes suggest the Pfizer vaccine may temporarily weaken the endothelium, even though patients did not suffer clear vision issues when the study was being conducted. Scientists said that for those with healthy eyes, these small changes likely may not affect vision right away. However, they may lead to corneal swelling or blurry vision, especially in those with pre-existing eye issues or those who have had a corneal transplant.
Researchers found that the average thickness of the cornea increased from 528 to 542 micrometres after two Pfizer doses, which is around a rise of 2 per cent. The endothelial cell count, which is responsible for keeping the cornea clear, dropped by about 8 per cent, from 2,597 to 2,378 cells per square millimetre.
Scientists urge caution
According to the study, which analysed the eye health with the help of Sirius corneal topography and Tomey EM-4000 specular microscopy, there is no need to halt the vaccination efforts. Scientists have rather called for ongoing monitoring of corneal health in those who already battle vulnerabilities in their eyes.
The researchers have also emphasised that the changes observed can be temporary responses to stress or inflammation that may resolve over time. Still, they warned that "the endothelium should be closely monitored in those with a low endothelial count or who have had a corneal graft", especially if future studies confirm long-term damage.
The Daily Mail said it also adds to existing concerns over rare side effects of mRNA vaccines, which include myocarditis and pericarditis, especially among younger men. The researchers plan to continue tracking participants to determine if these early corneal changes progress or stabilize over time.
Healthy endothelial cells are usually shaped like hexagons, which allows them to fit together tightly, like a honeycomb. Although the two per cent drop was not a direct sign of damage, it did suggest to the team that the cells may be reacting to some sort of stress over a significant period of time, like two months to three months.
Researchers also said their results showed evidence that the changes had a high likelihood of being directly linked to taking the vaccine, meaning it was not just a random anomaly in the testing. If the signs of stress and inflammation drop off shortly after receiving the Pfizer shot, the impact of these minor changes would not be overly harmful.
News
Nanoparticle blueprints reveal path to smarter medicines
Lipid nanoparticles (LNPs) are the delivery vehicles of modern medicine, carrying cancer drugs, gene therapies and vaccines into cells. Until recently, many scientists assumed that all LNPs followed more or less the same blueprint, [...]
How nanomedicine and AI are teaming up to tackle neurodegenerative diseases
When I first realized the scale of the challenge posed by neurodegenerative diseases, such as Alzheimer's, Parkinson's disease and amyotrophic lateral sclerosis (ALS), I felt simultaneously humbled and motivated. These disorders are not caused [...]
Self-Organizing Light Could Transform Computing and Communications
USC engineers have demonstrated a new kind of optical device that lets light organize its own route using the principles of thermodynamics. Instead of relying on switches or digital control, the light finds its own [...]
Groundbreaking New Way of Measuring Blood Pressure Could Save Thousands of Lives
A new method that improves the accuracy of interpreting blood pressure measurements taken at the ankle could be vital for individuals who are unable to have their blood pressure measured on the arm. A newly developed [...]
Scientist tackles key roadblock for AI in drug discovery
The drug development pipeline is a costly and lengthy process. Identifying high-quality "hit" compounds—those with high potency, selectivity, and favorable metabolic properties—at the earliest stages is important for reducing cost and accelerating the path [...]
Nanoplastics with environmental coatings can sneak past the skin’s defenses
Plastic is ubiquitous in the modern world, and it's notorious for taking a long time to completely break down in the environment - if it ever does. But even without breaking down completely, plastic [...]
Chernobyl scientists discover black fungus feeding on deadly radiation
It looks pretty sinister, but it might actually be incredibly helpful When reactor number four in Chernobyl exploded, it triggered the worst nuclear disaster in history, one which the surrounding area still has not [...]
Long COVID Is Taking A Silent Toll On Mental Health, Here’s What Experts Say
Months after recovering from COVID-19, many people continue to feel unwell. They speak of exhaustion that doesn’t fade, difficulty breathing, or an unsettling mental haze. What’s becoming increasingly clear is that recovery from the [...]
Study Delivers Cancer Drugs Directly to the Tumor Nucleus
A new peptide-based nanotube treatment sneaks chemo into drug-resistant cancer cells, providing a unique workaround to one of oncology’s toughest hurdles. CiQUS researchers have developed a novel molecular strategy that allows a chemotherapy drug to [...]
Scientists Begin $14.2 Million Project To Decode the Body’s “Hidden Sixth Sense”
An NIH-supported initiative seeks to unravel how the nervous system tracks and regulates the body’s internal organs. How does your brain recognize when it’s time to take a breath, when your blood pressure has [...]
Scientists Discover a New Form of Ice That Shouldn’t Exist
Researchers at the European XFEL and DESY are investigating unusual forms of ice that can exist at room temperature when subjected to extreme pressure. Ice comes in many forms, even when made of nothing but water [...]
Nobel-winning, tiny ‘sponge crystals’ with an astonishing amount of inner space
The 2025 Nobel Prize in chemistry was awarded to Richard Robson, Susumu Kitagawa and Omar Yaghi on Oct. 8, 2025, for the development of metal-organic frameworks, or MOFs, which are tunable crystal structures with extremely [...]
Harnessing Green-Synthesized Nanoparticles for Water Purification
A new review reveals how plant- and microbe-derived nanoparticles can power next-gen water disinfection, delivering cleaner, safer water without the environmental cost of traditional treatments. A recent review published in Nanomaterials highlights the potential of green-synthesized nanomaterials (GSNMs) in [...]
Brainstem damage found to be behind long-lasting effects of severe Covid-19
Damage to the brainstem - the brain's 'control center' - is behind long-lasting physical and psychiatric effects of severe Covid-19 infection, a study suggests. Using ultra-high-resolution scanners that can see the living brain in [...]
CT scan changes over one year predict outcomes in fibrotic lung disease
Researchers at National Jewish Health have shown that subtle increases in lung scarring, detected by an artificial intelligence-based tool on CT scans taken one year apart, are associated with disease progression and survival in [...]
AI Spots Hidden Signs of Disease Before Symptoms Appear
Researchers suggest that examining the inner workings of cells more closely could help physicians detect diseases earlier and more accurately match patients with effective therapies. Researchers at McGill University have created an artificial intelligence tool capable of uncovering [...]
