Fig 1.
Identification of the beta zone and the gamma zone in a B-scan image.
Scleral canal opening (white arrow), the edge of Bruch’s membrane (blue arrow), and the edge of the retinal pigment epithelium (red arrow) can be identified in a B-scan. A region between the termination of the retinal pigment epithelium and the termination of Bruch’s membrane is the beta zone, and a region between the termination of Bruch’s membrane and the scleral canal opening is the gamma zone. Scale bar = 200 μm.
Fig 2.
Measurements of the PPA zones.
Top) Left panel illustrates the OCT-defined PPA zones. White circle in the above schema represents the optic disc. Grey area around optic disc (bare sclera without overlying Bruch’s membrane) is the gamma zone. Dark grey area (Bruch’s membrane without overlying RPE) represents the beta zone. It is difficult to distinguish between the beta zone and the gamma zone on the photograph (right panel). Second from top) Reference line was placed at the level of the SCO (red line) in a horizontal OCT scan of the same eye. Right panel shows a corresponding en face image. The SCO can be identified as a border between highly reflective sclera and mid-intensity neural tissue (blue line). Third from top) Reference line was placed at the level of the termination of Bruch’s membrane. BMO can be seen as a border between highly reflective Bruch’s membrane and mid-intensity neural tissue in an en face image (right panel). Bottom) Reference line was placed at the level of the termination of RPE. RPE tip can be identified as a border between high intensity RPE and low intensity neural tissue.
Table 1.
Baseline characteristics of the groups.
Fig 3.
Scatterplots showing the correlation between axial length and A) the beta and B) the gamma zone parapapillary atrophy area.
Table 2.
Univariate regression analyses between patient characteristics and the beta zone and the gamma zone PPA area.
Table 3.
Multivariate regression analyses between patient characteristics and the beta zone and the gamma zone PPA area.
Table 4.
Clinical characteristics by subgroup categorized based on presence or absence of beta zone and gamma zone PPA.