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Definition of referable AMD and non-referable AMD in this study.
| Category | Stage | Definition | Classification |
|---|---|---|---|
| 1 | No AMD | No drusen or only small drusen ≤63 μm, and no pigment abnormalities | Non-referable AMD |
| 2 | Early AMD | Medium drusen >63 μm and ≤125 μm, and no pigment abnormalities | |
| 3 | Intermediate AMD | Large drusen >125 μm or any pigment abnormalities | Referable AMD |
| 4 | Advanced AMD | Neovascular AMD or geographical atrophy |
AMD: age-related macular degeneration.
