Table 1.

Summary Statistics for Inner and Outer Ratios for the Main Cohort (n = 2300) and Separately for Female (n = 2000) and Male (n = 300) Participants

	Inner Ratio			Outer Ratio
Parameter	All	Females	Males	All	Females	Males
Mean	0.89	0.89	0.90	0.84	0.84	0.88
Standard deviation	0.09	0.09	0.08	0.11	0.11	0.11
Median	0.90	0.90	0.90	0.84	0.84	0.87
2.5th Centile	0.71	0.70	0.78	0.61	0.61	0.69
97.5th Centile	1.07	1.07	1.09	1.05	1.04	1.16
Correlation with age (Spearman)	−0.17	−0.19	0.002	−0.21	−0.22	−0.13)
	(P = 1 × 10−8)	(P = 1 × 10−9)	(P = 0.98)	(P = 2 × 10−13)	(P = 9 × 10−13)	(P = 0.10)
Change per decade (standard error)	−0.0066 (0.0012)	−0.0079 (0.0013)	NS	−0.0097 (0.0015)	−0.0105 (0.0016)	NS

OCTs were obtained with the Optovue device (Optovue iVue 100, Optovue, Freemont, CA, USA) and segmented with automated software (Orion, Voxeleron LLC). For correlation with age and change per decade, the values from both twins from each twin pair were averaged. For male participants, no significant association with age was observed. NS, not significant.