Macular ridges: Prevalence and associated factors-The Beijing Eye Study.

Purpose: To explore the prevalence and associated factors of macular ridges in a population-based study sample.

Methods: From the participants of the population-based Beijing Eye Study (n = 3468), we included all eyes with an axial length of ≥25 mm and a randomized sample of the remaining myopic eyes. Using optical coherence tomographic images, we assessed the prevalence and height of macular ridges, defined as an elevation of the foveal region in one meridian.

Results: Among 366 study eyes, 50 (13.7%; 95% CI: 10.1, 17.2) showed macular ridges. Macular ridge prevalence increased from 0/78 (0%) in the group with an axial length of ≤23 mm to 18/71 (25.4%), 7/27 (25.9%) and 15/29 (51.7%) in axial length groups of 26-26.99 mm, 27-27.99 mm and ≥28 mm, respectively. Higher macular ridge prevalence was associated (multivariable analysis) with longer axial length (OR: 1.79; 95% CI: 1.48, 2.16; p < 0.001) and older age (OR: 1.08; 95% CI: 1.04, 1.12; p < 0.001). Macular ridge height (mean:128 ± 79 μm) increased with longer axial length (0.31; B: 7.84; 95% CI: 5.39, 10.3; p < 0.001) and older age (beta: 0.16; B: 0.88; 95% CI: 0.34, 1.42; p < 0.001). Macular ridge orientation was most often in the horizontal meridian (28/50 eyes; 56%), followed by the vertical meridian (9/50 eyes; 18%) and the 7 o'clock-to-1 o'clock meridian (8/50 eyes; 16%). It was not significantly (p = 0.17) associated with the axis of cylindrical corneal refractive error.

Conclusions: Macular ridges were relatively common in myopic eyes, with macular ridge prevalence and height increasing with longer axial length and older age in a curvilinear manner. They were not significantly associated with corneal astigmatism or best-corrected visual acuity. They may be explained by an inter-plane asymmetry in axial elongation-associated enlargement of Bruch's membrane in the fundus midperiphery.