Researchers recently identified a new sign of AMD progression that they say will be a useful endpoint for monitoring treatment effects, beyond relying on geographic atrophy (GA) lesion size progression. They found progressive photoreceptor degeneration was both evident and quantifiable in a cohort study of patients with GA secondary to AMD.

The study had three goals: to quantify photoreceptor degeneration outside the regions of GA in eyes with nonexudative AMD, to evaluate its association with future GA progression and to characterize its spatio-temporal progression. The study included 158 eyes of 89 patients in their seventies and eighties with a mean area of GA of 8.87 mm², as well as 93 normal eyes of 93 patients.

The researchers used fully automated segmentation with spectral domain OCT (SD-OCT) volume scans to quantify photoreceptor degeneration. B-scan segmentation was accurate and showed a marked interpatient variability in photoreceptor degeneration. The researchers noted that the ellipsoid zone loss-to-GA boundary distance and outer segment thickness were prognostic for future progression rates. Outer nuclear layer and photoreceptor inner segment thinning over time were also significant.

In the nonexudative AMD cohort, the team quantified distinct photoreceptor laminae alterations exceeding GA spatially. They concluded that macula-wide photoreceptor laminae thinning could be another endpoint for treatment monitoring.