Measurement of the angle on the ultrasound biomicroscopy image of the anterior segment.Angle-opening distance at 500 μm (AOD500) was measured on a line perpendicular to the trabecular meshwork at points 500 μm from the scleral spur. Trabecular-iris angle (TIA) was measured with the apex in the iris recess and the arms of the angle passing through a point on the trabecular meshwork 500 μm from the scleral spur and the point on the iris perpendicularly opposite.