Table 2. Geometrical measures of retinal arterioles by ethnic group.
| Measure | Europeans | South Asians | P |
| Arteriolar vessels, n | 12.9 [12.2, 13.7] | 10.8 [10.2, 11.5] | <0.001 |
| Arteriolar vessels (adjusted)§, n | 12.8 [12.1, 13.5] | 11.0 [10.2, 11.7] | 0.001 |
| Arteriolar bifurcations, n | 9.9 [9.3, 10.5] | 8.4 [7.9, 9.0] | <0.001 |
| Arteriolar bifurcations (adjusted)§, n | 9.7 [9.2, 10.3] | 8.6 [8.0, 9.1] | 0.004 |
| 1st order arterioles, n | 4.4 [4.1,4.7] | 3.9 [3.6, 4.2] | 0.04 |
| 2nd order arterioles, n | 5.1 [4.7, 5.4] | 4.1 [3.8, 4.4] | <0.001 |
| 3rd order arterioles, n | 2.1 [1.8, 2.3] | 1.4 [1.2, 1.7] | <0.001 |
| Arteriolar diameter, pixels | 22.5 [21.9, 23.0] | 22.7 [22.2, 23.3] | 0.5 |
| 1st order arteriolar diameter, pixels | 23.0 [22.5, 23.5] | 23.3 [22.8, 23.8] | 0.5 |
| Arteriolar length, pixels | 337 [323, 350] | 494 [465, 523] | <0.001 |
| Arteriolar length (adjusted)§, pixels | 341 [326, 356] | 369 [354, 383] | 0.01 |
| Arteriolar LDR | 15.3 [14.5, 15.9] | 16.8 [15.8, 17.7] | 0.01 |
| Optimality deviation | 0.067 [0.054, 0.080] | 0.080 [0.056, 0.104] | 0.3 |
| Arteriolar tortuosity (×102) | 1.23 [1.01,1.48] | 1.46 [1.24, 1.69] | 0.2 |
Values are mean [95% confidence interval] either unadjusted or § following adjustment for age, sex, systolic blood pressure, heart rate and diabetes. Abbreviations: LDR, length diameter ratio.