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Test loci. Scotopic thresholds were measured from all 12 loci shown (2°, 4°, 6°, 8°, 10°, and 12° eccentricity superior and inferior to the fovea) plus two additional locations at 18° eccentricity (not shown). Dark adaptation was measured from the eight loci shown in green (4°, 6°, 8°, and 12° eccentricity).
