Table 3

Mean (SD) HRT optic disc parameters and difference between the age quartiles in optic nerve head measurements by HRT I in normal eyes. Difference between the first and last quartile with statistical significance (p) (Mann-Whitney U test), r² for linear regression analysis. The age range of the quartiles was 35−40 years in the first quartile, 40−45 years in the second quartile, 45−52 years in the third quartile, 52−70 years in the last quartile

	882 participants, mean age 46.8 (SD 8.6) years; 1764 normal eyes
	Age quartile 1 (208 male, 14 female) (37.5 (SD 1.7) years), mean (SD)	Age quartile 2 (198 male, 23 female) (42.6 (SD 1.5) years), mean (SD)	Age quartile 3 (191 male, 27 female) (48.3 (SD 1.9) years), mean (SD)	Age quartile 4 (131 male, 90 female) (59.1 (SD 5.0) years), mean (SD)	Difference between quartiles 1 and 4
						p value	r²
*Mean retinal nerve fibre layer thickness (HRT).
†Significant.
Disc area (mm²)
RE	1.876 (0.41)	1.841 (0.36)	1.818 (0.39)	1.771 (0.42)	+0.105	0.011	0.013
LE	1.808 (0.41)	1.818 (0.36)	1.833 (0.45)	1.779 (0.37)	+0.029	0.755	0.002
Cup area (mm²)
RE	0.467 (0.32)	0.439 (0.31)	0.418 (0.30)	0.435 (0.34)	+0.031	0.178	0.002
LE	0.429 (0.32)	0.442 (0.31)	0.441 (0.34)	0.431 (0.32)	−0.029	0.953	0.001
Cup:disc area ratio
RE	0.233 (0.13)	0.224 (0.13)	0.216 (0.13)	0.226 (0.15)	+0.007	0.436	<0.001
LE	0.221 (0.13)	0.228 (0.13)	0.223 (0.14)	0.227 (0.14)	−0.006	0.627	<0.001
Rim area (mm²)
RE	1.409 (0.29)	1.402 (0.24)	1.400 (0.27)	1.336 (0.29)	+0.073	0.015	0.013
LE	1.378 (0.26)	1.376 (0.24)	1.392 (0.30)	1.348 (0.26)	+0.031	0.400	0.002
Mean RNFLT (mm)*
RE	0.269 (0.066)	0.269 (0.064)	0.264 (0.068)	0.251 (0.067)	+0.019	0.004†	0.011
LE	0.256 (0.063)	0.255 (0.065)	0.249 (0.068)	0.247 (0.064)	+0.009	0.162	0.004
Rim volume (mm³)
RE	0.391 (0.14)	0.389 (0.14)	0.384 (0.16)	0.356 (0.12)	+0.035	0.011	0.012
LE	0.368 (0.13)	0.362 (0.12)	0.362 (0.13)	0.351 (0.12)	+0.017	0.197	0.002