Customers in the United States need to be extra cautious about what eye drop products they choose to buy, as some options have the potential to cause dangerous infections.

Millions of people in the US use eye drops every day, so the relative risk of infection remains very, very low. Nevertheless, experts suggest customers stick to reputable, well-established brands while actively avoiding others.

Earlier this year, a rare strain of drug-resistant Pseudomonas aeruginosa bacterium triggered a multi-state outbreak of eye infections in the US, impacting more than 80 people.

The infections were connected to lubricating eye drops from the companies EzriCare and Delsam Pharma, prompting the Food and Drug Advisory (FDA) and the Centers for Disease Control and Prevention (CDC) to recall the products.

At least four people died from the drug-resistant P. aeruginosa infection, which can travel from the eye into the bloodstream, urine, and the lungs. More than a dozen other individuals were left with permanent vision loss, and four people had to have their eyeballs surgically removed.

Now, the FDA is warning against dozens of other over-the-counter eye drop products from the same manufacturing plant in India, including popular options sold at CVS Health, Rite Aid, Target, and Walmart.

While these products are supposed to be sterile, investigators at the FDA allegedly uncovered "insanitary conditions" at the facility. Samples from drug production areas showed positive results for some types of bacteria, although officials did not specify which pathogens were present.

The warning comes before the eye drops on the FDA's new 'watchlist' have been connected to any known eye infections.

It is not an official recall, but it is a warning that drug suppliers are taking seriously.

"CVS, Rite Aid and Target are removing the products from their store shelves and websites," reads a notice on the FDA website.

"Products branded as Leader, Rugby and Velocity may still be available to purchase in stores and online and should not be purchased."

If customers have already bought one or more of these products, the FDA recommends disposing of them at an official drug 'take-back' site. Either that, or customers can check the agency's official 'flush list' to see if the eye drop ingredients can safely go down the toilet.

Christopher Starr, a clinical spokesman for the American Academy of Ophthalmology, told The New York Times that customers should avoid touching the tip of their eye drop dispensers to the eye, skin, eyelashes, or fingers, as this can also contaminate the product with pathogens.

If patients or clinicians notice that eye drops are causing adverse symptoms, like eye redness, eye pain, light sensitivity, or eye discharge, they should stop using the products immediately and seek medical advice, and then report their experience to the FDA.