Early signs of geographic atrophy (GA) are detectable up to four years prior to disease onset, a new study finds.

The retrospective study analyzed SD-OCT and color photographs from 488 eyes with intermediate AMD. Of these eyes, 62 demonstrated new onset of GA. The researchers defined a size-matched control region in the same eye. They separately segmented these two areas and recorded their corresponding spatial volumes on SD-OCT at the GA incident year and at two, three and four years.

The researchers found that GA precursor regions had greater drusen volume, and at two and three years prior to GA onset, they were associated with hypertransmission, hyperreflective foci, OCT-reflective drusen substructures and loss or disruption of the photoreceptor zone, ellipsoid zone and retinal pigment epithelium. The researchers also found that precursor regions were associated with photoreceptor zone thinning and interdigitation zone loss at four years prior to GA onset.

They concluded that GA evolution is “heralded by early local photoreceptor changes and drusen accumulation, detectable four years prior to GA.” Importantly, they noted that these changes precede other anatomical indicators, including retinal pigment epithelium changes and drusen substructure emergence. The researchers suggest that these heralds be used as earlier endpoints and potential therapeutic targets in GA clinical trials.