Eye drops are widely used around the world to relieve dry eyes, irritation, and discomfort. Most people consider them safe because they are sold in pharmacies and are often available without a prescription.
However, a new study from researchers at Örebro University in Sweden suggests that one ingredient found in some eye drops may deserve closer attention.
The research focused on a chemical called perfluorohexyloctane. This substance is used in certain eye care products and has been considered largely inactive in the body.
Scientists have long believed that it passes through the body without causing significant biological effects. However, the new findings suggest that the chemical may not be as harmless as previously thought.
The study was published in the journal Environment International and investigated how perfluorohexyloctane affects human liver cells.
The researchers became interested in the chemical after questions were raised about the safety of ingredients used in eye drops. Since eye drops are often used regularly, sometimes several times a day, understanding their long-term effects is important.
Perfluorohexyloctane belongs to a group of chemicals that share similarities with PFAS. PFAS, often called “forever chemicals,” are man-made substances that are known for their ability to resist heat, water, and oil. They have been used in many products, including non-stick cookware, food packaging, stain-resistant fabrics, and firefighting foams.
Scientists have become increasingly concerned about PFAS because they can remain in the environment and in the human body for many years. Some studies have linked long-term PFAS exposure to health problems affecting the liver, immune system, and other organs.
Although eye drops are applied directly to the eyes, some ingredients can still enter the bloodstream. When eye drops drain through the tear ducts or are absorbed by surrounding tissues, small amounts of their ingredients may reach other parts of the body.
Earlier studies suggested that chemicals similar to perfluorohexyloctane can accumulate in the liver, which prompted researchers to investigate whether the same thing could happen with this compound.
The research team conducted laboratory experiments using human liver cells. Instead of exposing the cells to very high doses for a short period, they used smaller amounts over a longer time. This approach was chosen because it more closely resembles how people might be exposed to the chemical through regular use of eye drops.
The results revealed noticeable changes in the liver cells. The chemical altered the cells’ metabolism, which refers to the many processes that cells use to produce energy and handle nutrients and other substances. Healthy metabolism is essential for normal liver function, so changes in these processes can be important.
One of the most surprising findings was that perfluorohexyloctane appeared to transform inside the liver cells. The researchers found evidence suggesting that the chemical may be converted into a substance with characteristics similar to PFAS. This means the chemical may not remain unchanged after entering the body, as previously assumed.
According to the researchers, these findings do not prove that eye drops containing the chemical are harmful to people. Laboratory studies are an important first step, but they cannot fully predict what happens in the human body.
More research involving animals and human participants will be needed to determine whether the changes observed in liver cells could lead to health problems after long-term exposure.
The scientists also pointed out that perfluorohexyloctane is not used only in eye care products. Similar compounds can be found in a variety of medical, cosmetic, and hygiene products. This means understanding their safety is important for a much wider range of products than eye drops alone.
The study highlights a broader issue in public health. Many chemicals are approved for use because they appear safe based on the evidence available at the time. As scientific methods improve, researchers are sometimes able to detect effects that were previously overlooked.
This does not necessarily mean products are dangerous, but it does show why ongoing safety research is essential.
Professor Tuulia Hyötyläinen, one of the researchers involved in the study, said that regulators and manufacturers should carefully consider new scientific evidence when evaluating the safety of chemicals.
Interestingly, some related chemicals have already been banned from certain products, such as ski wax, because of concerns about their effects on health and the environment. Yet similar substances remain permitted in some medical products.
The researchers hope their findings will encourage further investigation into how these chemicals behave inside the body. Understanding long-term exposure is particularly important because many people use eye drops regularly for months or even years.
For consumers, the study should not be a reason to stop using prescribed or recommended eye drops. Instead, it serves as a reminder that scientists are continually learning more about how everyday products interact with the human body.
As more research becomes available, health authorities will be able to make better-informed decisions about which ingredients are safest for long-term use.
The findings from this study add an important piece to the growing scientific effort to understand the health effects of PFAS-related chemicals. While many questions remain unanswered, the research suggests that even common products can sometimes have unexpected effects that deserve closer examination.
If you care about eye health, please read studies about how vitamin B may help fight vision loss, and MIND diet may reduce risk of vision loss disease.
For more information about eye disease, please see recent studies about how to protect your eyes from glaucoma, and results showing this eye surgery may reduce dementia risk.
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