The number of patients diagnosed with a potentially blinding eye infection associated with injecting drugs, such as fentanyl or heroin, has more than doubled in recent decades, according to a United States study.
And those who injected fentanyl were more at risk of injection drug use-associated endogenous endophthalmitis (IDU-EE) than those injecting other opioids, such as heroin.
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 it’s theorised 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, including the eye.1
Because the infection can be either bacterial or fungal, it may take several days to weeks before symptoms appear. However, symptoms can worsen quickly if not treated properly.
Dr Jared Sokol, from the University of Colorado Anschutz Department of Ophthalmology, helped lead pivotal research on IDU-EE, recently published in Ophthalmology Retina.2
… the research also highlighted the important role ophthalmologists play in connecting patients with substance use disorders to addiction care
In a study based on patients at at Massachusetts Eye and Ear, they found the incidence of IDU-EE had more than doubled over the past two decades, likely due to increasing rates of injection drug use.
The researchers reviewed the treatment and outcomes for patients with IDU-EE and their findings highlight concerning trends of worsening visual acuity among some patients with IDU-EE, particularly among those who used fentanyl.
Dr Sokol said the research also highlighted 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,” Dr Sokol said.1 “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.”
“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,” Dr Sokol said.
“In our study, no patients in the outpatient setting were successfully connected with addiction medicine services.”
Dr Sokol said hospital admission was also important to ensure that the infection is not affecting other parts of the patient’s body, such as the heart.
Dr Sokol said 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. According to the study, fentanyl users 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,” Dr Sokol said. “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.”
References
- Shaw T. Research: Eye infection from injection drug use is rising, University of Colorado Anschutz Department of Ophthalmology, available at: news.cuanschutz.edu/ophthalmology/research-eye-infection-injection-drug-use [access July 2026].
- Sokol JT, Krasinski DJ, Gaier ED, et al. Substance use disorder interventions and ophthalmic outcomes for injection drug use-associated endogenous endophthalmitis. Ophthalmol Retina. 2026 May;10(5):543-551. doi: 10.1016/j.oret.2026.01.004.
