Table 3. Correlations of fundus parameters between family members.

Measurement	Intrafamilial relationship
	MZ twin pairs	Father-offspring pairs	Mother-offspring pairs	Pooled DZ and sibling pair
Right
Axial length*	0.87 (0.83–0.90)	0.32 (0.22–0.41)	0.37 (0.29–0.44)	0.41 (0.32–0.49)
Vertical cup-to-disc ratio‡	0.67 (0.58–0.74)	0.38 (0.29–0.47)	0.40 (0.33–0.47)	0.37 (0.28–0.46)
PPA to disc area ratio‡	0.53 (0.42–0.63)	0.23 (0.13–0.32)	0.14 (0.06–0.22)	0.26 (0.16–0.35)
PPA location†	0.58 (0.48–0.69)	0.12 (0.04–0.20)	0.11 (0.05–0.17)	0.19 (0.12–0.27)
Angular location of superior vein‡	0.25 (0.10–0.38)	0.08 (-0.03–0.18)	0.11 (0.03–0.20)	0.13 (0.02–0.22)
Angular location of inferior vein‡	0.18 (0.03–0.32)	0.09 (-0.01–0.19)	0.06 (-0.03–0.14)	0.07 (-0.03–0.17)
Angle ratio (superior/inferior)‡	0.13 (-0.01–0.27)	-0.02 (-0.12–0.09)	0.03 (-0.06–0.11)	-0.02 (-0.12–0.09)
Left
Axial length*	0.88 (0.84–0.91)	0.33 (0.23–0.41)	0.39 (0.31–0.46)	0.46 (0.37–0.53)
Vertical cup-to-disc ratio‡	0.65 (0.54–0.74)	0.37 (0.27–0.46)	0.35 (0.27–0.42)	0.31 (0.22–0.41)
PPA to disc area ratio‡	0.49 (0.37–0.59)	0.10 (0.00–0.20)	0.14 (0.05–0.22)	0.20 (0.10–0.29)
PPA location†	0.60 (0.50–0.70)	0.03 (-0.05–0.10)	0.13 (0.07–0.19)	0.11 (0.03–0.18)
Vertical cup-to-disc ratio‡	0.55 (0.44–0.64)	0.27 (0.17–0.36)	0.35 (0.27–0.42)	0.31 (0.22–0.41)
Angular location of superior vein‡	0.23 (0.09–0.37)	0.05 (-0.05–0.15)	0.12 (0.03–0.20)	0.15 (0.05–0.24)
Angular location of inferior vein‡	0.14 (0.00–0.28)	0.09 (-0.01–0.19)	0.02 (-0.07–0.10)	-0.01 (-0.11–0.09)
Angle ratio (superior/inferior)‡	0.13 (-0.02–0.27)	0.04 (-0.06–0.14)	0.01 (-0.08–0.09)	0.00 (-0.10–0.10)

Abbreviations: DZ, dizygotic twins; MZ, monozygotic twins; PPA, peripapillary atrophy.

* Estimated by the intra-class correlation coefficient (95% CI) after adjusting for age and sex.

† Estimated by the Cohen’s kappa coefficient (95% CI).

‡ Estimated by the intra-class correlation coefficient (95% CI) after adjusting for age, sex, intraocular pressure, and axial length.