Why this study matters

Stargardt disease (STGD) can lead to progressive damage in the macula—the central part of the retina responsible for detailed vision. On retinal imaging, this macular atrophy can sometimes resemble atrophy caused by other conditions, including geographic atrophy (GA) related to age-related macular degeneration (AMD) and certain inherited retinal dystrophies caused by changes in the PRPH2 gene. Understanding whether these conditions leave distinct measurable signatures in the retina could improve diagnosis, patient counselling, and the way disease progression is tracked over time.

A 2026 cross-sectional study in Investigative Ophthalmology & Visual Science examined a noninvasive imaging measure called quantitative fundus autofluorescence (qAF). The findings suggest that Stargardt disease has a notably different qAF pattern from GA secondary to AMD, PRPH2-associated retinal dystrophy, and healthy eyes.

What is quantitative fundus autofluorescence?

Fundus autofluorescence imaging captures naturally occurring fluorescent signals from the back of the eye. Quantitative fundus autofluorescence goes a step further: it uses a confocal scanning laser ophthalmoscope with an internal fluorescent reference to produce an objective, standardized measurement of that signal.

In this study, researchers focused on the mean qAF value from a standardized ring-shaped retinal measurement pattern called qAF8. Importantly, they removed areas of established atrophy from this pattern. This approach was designed to assess the remaining retina surrounding atrophic regions, rather than simply measuring the absence of signal within already damaged tissue.

The study compared four groups

The analysis included 208 eyes from 118 participants:

  • 87 eyes with geographic atrophy secondary to AMD
  • 22 eyes with Stargardt disease
  • 10 eyes with autosomal-dominant PRPH2-associated retinal dystrophy
  • 89 healthy control eyes

The researchers used statistical models that accounted for age when comparing groups. They also evaluated whether qAF8 was associated with the size of macular atrophy.

Stargardt disease showed elevated qAF

The central finding was that qAF8 differed significantly across the four groups. Eyes with Stargardt disease had significantly higher qAF8 values than healthy control eyes. They also differed significantly from eyes with GA secondary to AMD.

By contrast, the GA group had significantly lower qAF8 values than healthy controls, Stargardt disease, and PRPH2-associated retinal dystrophy. The PRPH2 group did not differ significantly from healthy controls.

In accessible terms, this means that the retinal area measured around macular atrophy showed a stronger autofluorescence signal in the Stargardt group than in healthy eyes, while the AMD-related GA group showed a weaker signal. These contrasting patterns may help explain why qAF could become a useful supporting tool when clinicians are distinguishing among disorders that can all involve macular atrophy.

A different relationship with atrophy size

The study also found different relationships between qAF8 and the extent of macular atrophy. In Stargardt disease, qAF8 had a significant positive correlation with atrophy area: larger areas of atrophy were associated with higher qAF8 measurements in the analyzed retinal region.

For GA and PRPH2-associated disease, the reported relationships were nominally inverse, meaning qAF8 tended to decrease as atrophy area increased, although these associations were not described as significant. This contrast reinforces the possibility that atrophy does not develop in the same biological context across these conditions, even when the retinal appearance may share some features.

What could this mean for care and future treatments?

The authors describe qAF as noninvasive and objectively acquired data that may serve as an adjunctive biomarker for diagnosis, prognosis, counselling, and management. For Stargardt disease, an imaging biomarker could eventually help clinicians track measurable retinal changes alongside standard clinical examinations and imaging.

This is particularly relevant as research continues to pursue treatments for inherited retinal diseases. Reliable biomarkers are valuable in research because they may help characterize disease status, compare groups of patients, and monitor change over time. However, this study does not establish qAF8 as a treatment-response measure, nor does it show that qAF can predict outcomes for an individual patient.

The findings also need to be interpreted with important study-design considerations in mind. Lens status was completely confounded with disease group, so it could not be evaluated independently. While age was included in the models, the authors note that residual confounding cannot be fully excluded because the groups only partially overlapped in age. Larger, more balanced cohorts will be important for confirming these results.

Looking ahead

This research adds to the growing effort to move beyond visual appearance alone and use standardized, quantitative retinal imaging in macular disease. The elevated qAF8 observed in Stargardt disease—and its positive association with atrophy size—distinguished it from AMD-related geographic atrophy in this study.

Further validation is needed before qAF can be routinely used to guide decisions. Still, the work points toward a future in which objective retinal measurements may complement genetic testing, clinical assessment, and established imaging to provide a more detailed picture of Stargardt disease and other causes of macular atrophy.