The raging opioid epidemic in the United States should prompt eye doctors to cast a suspicious gaze on patients seeking care for red and inflamed eyes, which could signal a problem far worse than a minor eye infection.

That’s the conclusion of ophthalmologists whose new research revealed a 400% increase in hospitalizations among drug users over a 13-year period for a rare and dangerous eye infection. Known as endogenous endophthalmitis, the infection is caused by bacteria or fungi that can get into the bloodstream – and often head toward the eyes – when IV drug abusers use dirty needles.

Published in the journal JAMA Ophthalmology , the study highlighted how the ongoing opioid epidemic – responsible for two out of three overdose deaths in the US – is taking a toll on vision, along with other aspects of health and well-being.

“We’re used to seeing people with inflammation in their eyes, but now we have a much higher likelihood of asking questions and diagnosing infections masquerading that way,” said study author David Hinkle, MD. He’s an associate professor of ophthalmology and visual sciences at West Virginia University School of Medicine in Morgantown.

“Nowadays you can’t tell who’s an opiate abuser – they’re just the regular people in our lives,” Dr. Hinkle told Medical Daily . “There’s no particular age, body type or income level to look for, and they’re not particularly forthcoming about using opiates. We have to keep what we call a high index of suspicion, not just in young people, but in middle-aged and older people, too.”

Changing dynamics surrounding opioids

More than 10 million people in the United States aged 12 and older misused opioids in 2017-18, including 808,000 who used heroin, according to the US Department of Health and Human Services.

But Dr. Hinkle noted that after 2010 greater numbers of prescription opioid addicts turned to cheaper and more-available street heroin and synthetic opioids such as fentanyl, which are typically injected. That is when regulators began monitoring doctors’ opioid prescribing habits more closely. The defunding of many states’ needle exchange programs around the same time also contributed to sharing dirty needles, he said.

Dr. Hinkle and his colleagues reviewed national hospital inpatient data spanning from 2003 to 2016. More than 56,800 patients were admitted to the hospital with a diagnosis of endogenous endophthalmitis during that period, and 13.7% had a history of drug dependence or use.

About 56% of all patients with this infection were white, while 13.6% were black and 10.6% were Hispanic. Drug-using patients’ average age was late forties, and 62% were men.

The prevalence of endogenous endophthalmitis among hospitalized patients linked to drug use or dependence increased four-fold during the study period. Moreover, the increase was seen across all regions of the US.

Eyes especially vulnerable

While bacteria or fungi that get into the bloodstream through dirty needles can infect many organs, the eyes are especially susceptible because they’re rich in blood vessels, Dr. Hinkle explained.

“The back of the eye has the highest blood flow for the mass of material that’s there than any area in the body,” he said, “so organisms tend to get trapped back there because it’s the end of the line as far as blood vessels are concerned. Even if you’re treated for this infection, you can still be blinded by scarring that happens from the infection that destroys the retina.”

Awareness counts

Abdhish Bhavsar, MD, a clinical spokesperson for the American Academy of Ophthalmology, agreed that the study drives home the need for eye care professionals to be on the lookout for patients who don’t mention drug use but present with inflamed eyes.

“Inflammation in the eye can be both non-infectious or infectious, so clinicians should maintain a high suspicion and inquire especially about IV drug use,” said Dr. Bhavsar, who is director of the Retina Center in Minneapolis.

“We all have bias, and physicians have to recognize their bias just like everyone else,” he added. “We need to be aware how bias might steer us away from making a diagnosis or not making a diagnosis.”

Dr. Bhavsar also advised people who use IV drugs to be upfront with their doctors.

“People should not be ashamed to let their doctors know,” he said, “because the care they get can be that much more accurately delivered if the physician treating you knows this information.”

Maureen Salamon writes about health and medicine for websites, magazines and hospitals such as Medscape, St. Jude Children’s Research Hospital, Weill Cornell Medicine and others.