The SFCT was measured using the manual calipers of the proprietary device, was taken at the fovea, and was defined as the distance between the outer part of the hyper-reflective line corresponding to the base of the RPE and the hypo-reflective line or margin corresponding to the sclerochoroidal interface4. The SFCT values of the horizontal and the vertical scans were averaged for analysis. The depth of subfoveal linear artifact was measured from the base of the RPE to the upper end of the three hyper-reflective bands similar to the ellipsoid zone, the interdigitation zone and the RPE/Bruch’s complex. As demonstrated in Fig. 4, the thickness of the linear artifact was defined as the distance between the upper and the lower end of the three hyper-reflective bands. Each OCT figure was reviewed by at least two of the readers. The SFCT and the depth and the thickness of the linear artifact were measured by at least two experienced readers independently and the values were averaged to get the reported results if the difference in the measurements of the readers was within 15% of the mean of the values. In a few cases, there was disagreement in measurement, and the determination was referred to Dr. Liu, the senior author.Figure 4The linear artifact line measured by EDI-OCT. The height from the ellipsoid zone to RPE/Bruch’s complex and the depth and height of the linear artifact are demonstrated. RPE: retinal pigment epithelium.