Across the central 5 mm, significant topographical variations in thickness were found in both Indigenous and non-Indigenous children (
Fig. 2,
Table 2). For both groups combined, the choroid was thickest in the central fovea, becoming significantly thinner in the parafovea (estimated mean difference 11 µm, 95% confidence interval [CI] = 9.2–12.6 µm) and perifovea (estimated mean difference 35 µm, 95% CI = 31–39 µm; all pairwise comparisons
P < 0.001;
Fig. 2A). The choroid was thinnest nasally and inferiorly and thickest superiorly and temporally (
Fig. 2B). Similar to the subfoveal analyses, significant associations between macular choroidal thickness and age (F
1,238 = 30.1,
P < 0.001) and axial length (F
1,238 = 7.1,
P = 0.008) were also observed.
The average macular choroidal thickness was significantly greater (F
1,238 = 7.1,
P = 0.008) in Indigenous children compared to non-Indigenous children (across all eccentricities and meridians, estimated mean difference = 22 µm, 95% CI = 6–39 µm). A significant interaction between meridian and Indigenous status was also observed (F
3.2,755 = 4.0,
P = 0.007), with the largest differences between Indigenous and non-Indigenous children observed in the nasal (estimated mean difference = 27 µm, 95% CI = 11–44 µm,
P = 0.001) and inferior nasal (estimated mean difference = 28 µm, 95% CI = 12–45 µm,
P = 0.001) meridians, and the smallest difference in the superior meridian (estimated mean difference = 14 µm, 95% CI = −4–31 µm,
P > 0.05;
Fig. 2B). However, there was no significant eccentricity by Indigenous status interaction (F
1.1,257 = 1.7,
P > 0.05) indicating that the difference in thickness between Indigenous and non-Indigenous children was similar between the foveal, parafoveal and perifoveal zones.
Figure 3 illustrates the mean macular topographical thickness maps for the Indigenous children and non-Indigenous children, and the mean thickness difference between groups, highlighting the meridional differences in thickness between groups across the central 5 mm macular region.