For millions of people, age-related macular degeneration (AMD) gradually blurs central vision, making everyday tasks like reading and driving difficult. In its most severe form— “wet” AMD—abnormal blood vessels grow under the retina and leak fluid, causing rapid damage. 

Treatments that block a growth factor called VEGF have transformed care, often stabilizing vision. But one question remains: Why do some patients respond well while others continue to lose vision?

A new study from University of Iowa researchers offers an important clue. Titled “MMP9 Genotype and Systemic T Cell Subsets Correlate with Structural and Functional Outcomes in Neovascular Age-Related Macular Degeneration,” the research was funded by the National Eye Institute (NEI), Research to Prevent Blindness, and individual philanthropic support. The multidisciplinary team collaborated across the Carver College of Medicine, the College of Public Health, the College of Engineering, and the Holden Comprehensive Cancer Center. By linking genetics, immune activity, and detailed retinal imaging, the team identified factors that may explain these differences—and point toward more personalized treatment.

More Than a Blood Vessel Disease

Wet AMD has long been viewed as a problem of abnormal blood vessel growth. But this study reinforces a broader understanding: AMD also involves the immune system.

Chronic inflammation is increasingly recognized as part of the disease, and the researchers found evidence that systemic immune activity—throughout the body—may influence what happens in the eye. 

The Role of the MMP9 Gene

At the center of the study is MMP9, a gene that produces an enzyme that breaks down structural tissue. In the eye, this can weaken barriers beneath the retina and promote abnormal vessel growth.

While MMP9 variations were already linked to AMD risk, this study is among the first to show they may also influence disease severity and treatment outcomes.

A High-Tech Approach

The researchers combined several advanced tools:

• Genetic testing of AMD patients
• AI-based analysis of retinal scans to measure fluid (a sign of disease activity)
• Immune profiling of T cells in the blood

Using internally developed, explainable artificial intelligence allows for fully automated, precise, objective measurement of retinal fluid—more sensitive than traditional methods.

Key Findings

1. Genetics matter

Patients with a specific MMP9 variant—the TC genotype—had:

• More retinal fluid
• Worse vision changes over time

Notably, the pattern was complex: having two risk copies didn’t always mean worse outcomes, suggesting non-linear genetic effects.

2. The immune system is linked to outcomes

Different types of T cells were strongly associated with disease activity:

• Some were tied to persistent retinal fluid and worse vision
• Others were linked to better disease control

This suggests the immune system plays a role in how well patients respond to treatment.

3. A new disease pathway

The study proposes a new mechanism:

• Dendritic cells in the choroid (the vascular supply of the retina’s light sensing cells) produce MMP9
• MMP9 alters the ocular environment
• This influences T cell behavior, promoting inflammation and abnormal blood vessel growth

Researchers describe this as an “MMP9–dendritic cell–T cell axis.” 

Why This Matters

Toward personalized care

In the future, doctors may be able to use genetic and immune testing to better predict disease severity and potentially tailor treatment plans—including injection frequency or alternative therapies

New treatment targets

Current therapies focus on blocking VEGF. This research suggests additional targets:

• MMP9
• Immune system pathways driving inflammation

These could lead to therapies for patients who don’t respond well to existing treatments.

A broader understanding

The findings support a shift in thinking: AMD may be both an eye disease and a systemic immune condition.

Looking Ahead

Your genes and your immune system may influence how macular degeneration progresses—and how well treatment works.

That insight could help usher in a new era of personalized care for AMD, where treatment is guided not just by the eye, but by the whole patient.