Study aims to understand mpox-related vision loss

A $2.8 million R01 grant from the National Eye Institute, part of the National Institutes of Health, is funding a multinational effort led by Steven Yeh, MD, professor and the Stanley M. Truhlsen Jr. Chair of Ophthalmology, to understand an underrecognized complication of mpox: sight-threatening eye disease.

The project brings together investigators from the University of North Carolina, the University of Illinois Chicago and Emory University, alongside colleagues in the Democratic Republic of the Congo and Sierra Leone.

As mpox cases continue to surface in the United States, United Kingdom, Canada, India and Thailand, Dr. Yeh and colleagues are working to answer a question with life-altering stakes: how does the virus damage the eyes, and can that damage be prevented? While U.S. case numbers have declined since the initial 2022-2023 outbreak, Dr. Yeh said the disease remains active in parts of Central and West Africa, where it is endemic and continues to evolve.

“Because there can be ocular manifestations, some of which can cause visual impairment and some that can be devastating, there still remains an imperative to understand the disease comprehensively,” both for patients and for the healthcare providers who treat them, Dr. Yeh said. During work in the Democratic Republic of Congo, Dr. Yeh said his team encountered several healthcare workers who developed severe eye infections from mpox, some resulting in vision loss—loss that, even in the United States with access to corneal transplantation, can be permanent.

Mpox can affect the eye in several ways, Dr. Yeh said, ranging from conjunctivitis to keratitis, inflammation of the cornea to lesions around the eyelids and, in rare cases, uveitis, a severe internal eye inflammation.

For patients who have a systemic diagnosis of mpox and have ocular symptoms, the disease can escalate to vision loss within days, he said.

The study also aims to clarify how long the virus persists in patients’ tears after infection — data Dr. Yeh said remains limited, despite rare reports of the virus resurfacing after appearing to clear. Understanding that timeline, he said, is key to guiding how long patients should be monitored and what infection-control precautions are needed.

A central question is whether one of the two major mpox clades, or grouping of viruses, causes more severe eye disease than the other. Published data suggests clade I may carry a higher risk, but Dr. Yeh said prevalence appears to vary between populations, underscoring the need for more comprehensive study.

The five-year study builds on the team’s long-running work in Ebola response, and Dr. Yeh expects new questions to emerge as the research unfolds. Ultimately, he said, the goal is straightforward: better tools to prevent and treat vision loss from mpox for patients in the U.S. and around the world.