This cross-sectional study compared peripapillary RNFL (pRNFL) and macular layer thickness (via Heidelberg OCT) between 50 elderly adults with mild-to-moderate Alzheimer's disease (AD) and 50 age-matched healthy controls (HCs), while also assessing depression severity (PHQ-9) and cognition (MMSE) in both groups.
AD patients had significant thinning in supra-temporal pRNFL (127.45 vs. 136.38 µm, P=0.010), infra-temporal pRNFL (127.99 vs. 139.46 µm, P=0.003), GCL volume (0.981 vs. 1.043 mm³, P<0.001), IPL volume (0.834 vs. 0.872 mm³, P=0.001), and GCC (2.671 vs. 2.832 mm³, P<0.001). Depression severity independently correlated with lower GCL volume (ρ=−0.260, P=0.009), and an AD × depression interaction showed that co-existing depression worsened GCL thinning beyond AD alone (β=−0.213, P=0.020).
- Cross-sectional design prevents causal inference or tracking of retinal changes over time. - Depression was assessed by PHQ-9 only; no clinical diagnosis of major depressive disorder was confirmed. - Sample limited to mild-to-moderate AD; findings may not generalize to severe AD or other dementias.
OCT-measured inner retinal thinning (GCL, IPL, pRNFL) is meaningful in AD patients, but co-existing depression adds further thinning—so clinicians should account for both conditions when using OCT to screen for glaucoma or monitor neurodegeneration in elderly patients. Reliable visual field testing is also harder in AD, making OCT interpretation even more context-dependent.
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