Figure 2.

Graph of the vertical cup-to-disc ratio of the right eye minus the left eye, versus age, for patients observed to have at least a 0.10 cup-to-disc ratio asymmetry.

Notes: The eye with the larger optic cup coincided with the side of sleep preference 78% of the time, P≤0.001, n=137. Patients who reported they slept on their right side appear as • and those who preferred their left side as +. Patients with larger cup-to-disc ratios in the right eye who preferred a right-sided sleep posture therefore appear as a • above the horizontal and those with a larger cup-to-disc ratio in the left eye who preferred a left-sided sleeping posture appear as a + below the horizontal.