Table 1. Characteristics of the five study populations presented as mean ± standard deviation (range) unless stated otherwise.

	RS-I/RS-II	RS-III	ERF	TwinsUK
Total sample size (N)	7,360	1,966	1,646	843
Age (years)	67.0±8.4 (55–99)	55.6±5.5 (45–89)	46.8±14.1 (18–84)	56.1±12.7 (16–83)
Gender, N(%) female	4,208 (57.2)	1,102 (56.1)	942 (57.2)	818 (97.0)
Disc area (mm2)*	2.40±0.48 (0.58–6.20)	1.92±0.45 (0.70–7.20)	1.92±0.37 (1.07–4.33)	2.59±0.65 (0.75–6.96)
Vertical cup-disc ratio*	0.50±0.14 (0.00–0.89)	0.42±0.17 (0.00–1.00)	0.46±0.15 (0.00–0.84)	0.32±0.10 (0.07–0.70)

*In RS-I, RS-II and TwinsUK measured with stereoscopic images, in RS-III and ERF with confocal scanning laser ophthalmoscopy.