Amid the ongoing opioid epidemic, the number of patients diagnosed with a potentially blinding eye infection associated with injecting drugs, such as fentanyl or heroin, has increased in recent decades, raising national concern among ophthalmologists and addiction care clinicians.
Aiming to uncover better ways to treat patients with this condition, known as injection drug use-associated endogenous endophthalmitis (IDU-EE), Jared Sokol, MD, an assistant professor and retinal specialist at the University of Colorado Anschutz Department of Ophthalmology, helped lead pivotal research that was recently published in the Ophthalmology Retina journal.
The research began while Sokol was a resident at Massachusetts Eye and Ear at Harvard Medical School, where he noticed there was an uptick in the number of patients diagnosed with IDU-EE. He and his co-investigators found that from 2015-2021, there were 62 patients diagnosed with this condition at the institution, meanwhile previous research at the same location found that from 2006-2014 there were 30 patients identified with it — representing a more than 106% increase over a shorter time period.
The researchers reviewed the treatment and outcomes for the 62 patients as well as whether the patients had been connected to addiction services. Their findings highlight concerning trends of worsening visual acuity among some patients with IDU-EE, particularly among those who used fentanyl, and the important role ophthalmologists play in connecting patients with substance use disorders to addiction care.
“In ophthalmology, we don’t just treat the eyes. We think about the whole patient,” Sokol says. “When we identify a condition that is related to injection drug use, it’s important that we connect patients with the right resources because these interventions may not only help save their vision but also their lives.”
Investigating a rare infection
Endogenous endophthalmitis is a severe infection inside the eye that stems from an infection elsewhere in the body, such as an infection from liver abscesses or sepsis. In some rare cases, this infection can originate from injecting drugs into the body.
Much is still unknown about IDU-EE, but ophthalmologists theorize that the infection may be caused by the introduction of bacteria or fungus through the skin when a drug is injected. This may introduce dangerous pathogens into the bloodstream that can travel to different parts of the body.
“Since the eye is a vascular organ, those pathogens can end up in the eye and proliferate. We don’t know exactly why that happens, but if the condition gets severe enough, then patients will experience symptoms like red eye, pain, or blurry and worsening vision,” Sokol says.
The infection can affect tissues and fluid within the eye, and damage the retina, which helps send visual information to the brain. The infection can be bacterial or fungal, so it may take several days to weeks before symptoms appear. However, symptoms can worsen quickly if not treated properly.
Once identified, ophthalmologists treat the infection aggressively. They take a small fluid sample from the eye for laboratory testing to identify whether it is fungal or bacterial, then immediately inject antibiotics and/or antifungals into the eye.
“Some patients with more severe infections will undergo surgery,” Sokol says. “We will perform a vitrectomy where we essentially clean out the back of the eyeball, remove the infectious debris, and survey as much as we can. We will administer antibiotics or antifungals in the eye and then let it heal.”
On the frontlines of the opioid epidemic
The incidence of IDU-EE has increased over the last two decades, likely due to increasing rates of injection drug use, researchers say in the study.
Patients with IDU-EE oftentimes initially go to an urgent care or the emergency department to get medical help after ocular symptoms appear, but because this infection is introduced into the body from a site distant from the eye, it can be confusing and difficult to diagnose, Sokol explains. This can lead to an initial misdiagnosis. It’s usually not until the patient is referred to an ophthalmologist that they will find out they have endogenous endophthalmitis.
“It can be difficult to determine whether the infection was due to injection drug use because there is a social stigma that influences what people are willing to share and what questions physicians ask. This stigma probably leads to delayed diagnoses and fewer people going to the doctor for this condition, allowing the infection to worsen before treatment can be initiated,” Sokol says. “It’s important for us to ask patients if they have injected any drugs so we can better help them.”
In their study, the researchers write that ophthalmologists “are on the frontlines of the ongoing opioid epidemic” and can help facilitate a multidisciplinary approach to the care of people with substance use disorders. Many patients with IDU-EE are adults under the age of 40 who do not have consistent medical care, Sokol explains.
“It creates a unique touch point between ophthalmologists and patients who inject drugs. That’s why, in this study, we wanted to look at both the clinical outcomes of these patients and the role of addiction medicine services,” he says.
Hospital admission vs. outpatient care
Of the 62 patients with IDU-EE, 60 patients reported injection opioid use, primarily injecting heroin and/or fentanyl, according to Sokol’s research. Fifty-four patients were admitted to a hospital — a step that the researchers say is valuable to helping patients get multidisciplinary care.
“We feel that all patients with this condition should be admitted to the hospital. In addition to aggressive ophthalmic treatment, inpatient treatment helps patients get addiction medicine care to address substance use disorders,” Sokol says. “In our study, no patients in the outpatient setting were successfully connected with addiction medicine services.”
In comparison, of those patients who were admitted to the hospital, 37 agreed to receive an addiction consult service, and all eligible patients were offered medication for opioid use disorder (MOUD), such as buprenorphine, methadone, or naltrexone.
“Addiction consult service (ACS) involvement is independently associated with improved retention in care, reduced substance use after hospital discharge, and decreased mortality and re-admissions among people who inject drugs,” the researchers write. “Although this is a retrospective, observational study, our results offer compelling evidence that ACS involvement in cases of IDU-EE is associated with higher rates of MOUD initiation.”
Another reason why Sokol believes patients with IDU-EE should be admitted to the hospital is to ensure that the infection is not affecting other parts of their body, such as the heart. One benefit of working at the Sue Anschutz-Rodgers Eye Center at CU Anschutz is that the eye center is connected to a UCHealth hospital, making it easier to ensure patients have access to multidisciplinary care.
“The fact that we are a tertiary referral center and have resources within the inpatient setting to offer patients addiction medicine consultation puts us in a position to treat these patients holistically,” Sokol says. “We have many resources that really allow us to treat these patients as best as we can.”
Worse outcomes associated with fentanyl
For Sokol, one of the most surprising findings in the study was that patients who injected fentanyl had worse visual outcomes compared to patients who injected other drugs, such as heroin.
According to the study, patients who reported injecting fentanyl had more than fivefold increased odds of being unable to read the eye chart at a final follow-up appointment compared to those who did not.
“We didn’t quite fully understand why that was,” Sokol says, explaining that the treatment approaches were similar. “Fentanyl is a very potent drug and has been a big driver in the opioid epidemic, so that may be a contributing factor. Other causes may be an evolution of pathogens and an increase in antibiotic resistance, but further research is needed on this.”
The researchers also found that the patients in the 2015-2021 study, overall, had worse visual outcomes in some instances compared to patients in the 2006-2014 study. For example, in the more recent study, 28% fewer patients showed visual acuity improvement between when they first presented and their last follow-up appointment. There also was no reported fentanyl use in the previous study’s patient cohort.
“Overall, our main findings were that there was a higher incidence of patients presenting with this condition, and more patients ultimately had worse visual outcomes,” Sokol says. “It’s important for the public to know that an ocular condition can be the first sign of a systemic issue within the body, so getting regular eye exams and seeking care for new symptoms is important. For ophthalmologists, we are in a unique position to diagnose these conditions and help connect patients to the multidisciplinary care they need.”
