The research protocol was approved by the institutional review board at the Oregon Health & Science University (OHSU) and performed in accordance with the tenets of the Declaration of Helsinki. Written informed consent was obtained from each participant after explanation of the nature and possible consequences of the study. Participants were recruited at the Casey Eye Institute/OHSU according to the AIG study protocol. The OHSU ancillary site followed the same eligibility and endpoint protocol as the AIG study, but used an advanced swept-source OCT prototype system instead of commercially available OCT instruments. The inclusion and exclusion criteria of the AIG study have been reported previously.
4 Briefly, normal control participants met the following criteria in both eyes: IOP of less than 21 mm Hg in both eyes, and a normal Humphrey visual field (HVF) on achromatic standard automated perimetry by Swedish Interactive Threshold Algorithm 24-2 testing (HFA II; Carl Zeiss Meditec, Inc., Dublin, CA, USA) with mean deviation (MD), Glaucoma Hemifield Test (GHT), and pattern standard deviation (PSD) within normal limits. In addition, normal subjects had a normal-appearing optic nerve head (ONH) and NFL on ophthalmoscopic examination, and an open angle by gonioscopy. Glaucoma participants were required to have a glaucomatous ONH rim or NFL thinning on ophthalmoscopic examination. Glaucomatous eyes were classified in the PG subgroup if they have visual field (VF) PSD or GHT outside normal limits (
P < 0.05 and
P < 1%, respectively) in a consistent pattern on two qualifying VF exams. Otherwise, they were classified as preperimetric glaucoma (PPG). Exclusion criteria for all groups included visual acuity less than 20/40, age <40 or >79 years at enrollment, any ocular surgery other than uncomplicated cataract extraction, other diseases that might cause VF or ONH abnormality, and factors that might preclude the participant from performing study procedures or completing the study.