All participants were examined by two retinal specialists independently of each other. Two high-quality horizontal and vertical 9 mm EDI line scans across the fovea were obtained from each eye using the spectral-domain OCT device (wavelength: 870 nm; scan pattern: enhanced depth imaging; Spectralis; Heidelberg Engineering, Heidelberg, Germany). Eye motion artifacts were eliminated by a proprietary eye tracking device, and 100 frames of EDI OCT images were captured and automatically averaged to reduce speckle noise.