Simultaneous stereoscopic optic disc photographs (TRC-SS; Topcon Instrument Corp of America, Paramus, NJ) were reviewed using a stereoscopic viewer (Asahi Pentax Stereo Viewer II; Asahi Optical Co., Tokyo, Japan). For progression assessment, each patient’s most recent stereophotograph was compared to their baseline stereophotograph. Definition of change was based on focal or diffuse thinning of the neuroretinal rim and increased excavation, appearance, or enlargement of RNFL defects. Evidence of progression was based on masked (patient name, diagnosis, temporal order of photographs) comparison between the baseline and most recent photograph, by two observers. If these observers disagreed, a third observer served as an adjudicator. Overall agreement among observers in the evaluation of progression was 0.91.