Factors associated with macular thickness in the COMET myopic cohort

Abstract

Purpose: To determine whether macular thickness is associated with ethnicity, gender, axial length (AL), and severity of myopia in a cohort of young adults from the Correction of Myopia Evaluation Trial (COMET).

Methods: Eleven years after their baseline visit, 387/469 (83%) subjects returned for their annual visit. In addition to the protocol-specific measures of spherical equivalent refractive error (SER) and AL, high-resolution macular imaging also was performed with optical coherence tomography (RTVue). From these scans, full-thickness values for the central (1 mm), parafoveal (1 to 3 mm), and perifoveal (3 to 5 mm) annular regions were calculated. Gender, ethnicity, AL, and SER were examined for associations with macular thickness using univariate and multivariable linear regression analyses.

Results: In the 377 subjects with usable data (mean age = 21.0 ± 1.3 years), the mean SER ± SD was -5.0 ± 1.9 D and mean AL was 25.4 ± 0.9 mm. Mean foveal thickness was 252.0 ± 20.1 μm in the center, 315.6 ± 14.0 μm in the parafovea, and 284.4 ± 12.9 μm in the perifovea. In the best-fit multivariable model that adjusted for gender, ethnicity, and AL, females had significantly thinner maculas than males for all three regions (p < 0.0001), with the largest difference in the center (12.8 μm, 95% confidence interval: 9.2 to 16.4). The effect of ethnicity was strongest in the central fovea, with African-Americans, Asians, Hispanics, and mixed ethnic groups having thinner maculas than whites (all p values < 0.005). Increased AL was significantly associated with slightly thicker central foveas (p = 0.001) and thinner parafoveal (p = 0.02) and perifoveal (p < 0.0001) regions.

Conclusions: In this ethnically diverse cohort of moderate and high myopes, females and African-Americans were found to have the thinnest central foveas. Whether such thinning in the macula as a young adult is a risk factor for future disease remains to be determined.

Figure 1

Macular thickness measurements (mean ± SD) for each region by gender. The innermost circle represents the central 1.0 mm of the fovea, the inner ring represents the para-foveal region (1.0 – 3.0 mm), and the outer ring represents the peri-foveal region (3.0 – 5.0 mm).

Figure 2

Macular thickness measurements (mean ± SD) for each region (as defined in the Figure 1 caption) by ethnicity.

Figure 3

(a–c): Scatter plots of the association between macular thickness and axial length, in both males (filled circles) and females (open triangles), in the central fovea (a), para-fovea (b) and peri-fovea (c).

Figure 4

(a–c): Scatter plots of the associations between macular thickness and spherical equivalent refractive error, in males (filled circles) and females (open triangles) in the central fovea (a), para-fovea (b) and peri-fovea (c).